2022
Aghaee, Morteza; Akkala, Arun; Alam, Zulfi; Ali, Rizwan; Ramirez, Alejandro Alcaraz; Andrzejczuk, Mariusz; Antipov, Andrey E; Astafev, Mikhail; Bauer, Bela; Becker, Jonathan; others,
InAs-Al hybrid devices passing the topological gap protocol Journal Article
In: arXiv preprint arXiv:2207.02472, 2022.
@article{aghaee2022inas,
title = {InAs-Al hybrid devices passing the topological gap protocol},
author = {Morteza Aghaee and Arun Akkala and Zulfi Alam and Rizwan Ali and Alejandro Alcaraz Ramirez and Mariusz Andrzejczuk and Andrey E Antipov and Mikhail Astafev and Bela Bauer and Jonathan Becker and others},
year = {2022},
date = {2022-01-01},
journal = {arXiv preprint arXiv:2207.02472},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Harlech-Jones, B; Waddy, SJ; Witt, JDS; Govender, D; Casparis, L; Martinez, E; Kallaher, R; Gronin, S; Gardner, G; Manfra, MJ; others,
Local and Non-local Microwave Impedance of a Three-Terminal Hybrid Device Journal Article
In: arXiv preprint arXiv:2207.12516, 2022.
@article{harlech2022local,
title = {Local and Non-local Microwave Impedance of a Three-Terminal Hybrid Device},
author = {B Harlech-Jones and SJ Waddy and JDS Witt and D Govender and L Casparis and E Martinez and R Kallaher and S Gronin and G Gardner and MJ Manfra and others},
year = {2022},
date = {2022-01-01},
journal = {arXiv preprint arXiv:2207.12516},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stace, Thomas M.; Chen, Jiayin; Li, Li; Perunicic, Viktor S.; Carvalho, Andre R. R.; Hush, Michael R.; Valahu, Christophe H.; Tan, Ting Rei; Biercuk, Michael J.
Optimised Bayesian system identification in quantum devices Miscellaneous
2022.
@misc{stace2022optimised,
title = {Optimised Bayesian system identification in quantum devices},
author = {Thomas M. Stace and Jiayin Chen and Li Li and Viktor S. Perunicic and Andre R. R. Carvalho and Michael R. Hush and Christophe H. Valahu and Ting Rei Tan and Michael J. Biercuk},
year = {2022},
date = {2022-01-01},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
2021
Darmawan, Andrew S.; Brown, Benjamin J.; Grimsmo, Arne L.; Tuckett, David K.; Puri, Shruti
Practical Quantum Error Correction with the XZZX Code and Kerr-Cat Qubits Journal Article
In: PRX Quantum, vol. 2, no. 3, 2021, ISSN: 2691-3399.
BibTeX | Links:
@article{Darmawan_2021,
title = {Practical Quantum Error Correction with the XZZX Code and Kerr-Cat Qubits},
author = {Andrew S. Darmawan and Benjamin J. Brown and Arne L. Grimsmo and David K. Tuckett and Shruti Puri},
url = {http://dx.doi.org/10.1103/PRXQuantum.2.030345},
doi = {10.1103/prxquantum.2.030345},
issn = {2691-3399},
year = {2021},
date = {2021-09-01},
journal = {PRX Quantum},
volume = {2},
number = {3},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tan, T. R.; Edmunds, C. L.; Milne, A. R.; Biercuk, M. J.; Hempel, C.
Precision characterization of the D-2(5/2) state and the quadratic Zeeman coefficient in Yb-171(+) Journal Article
In: PHYSICAL REVIEW A, vol. 104, no. 1, 2021, ISSN: 2469-9926.
@article{WOS:000680425800011,
title = {Precision characterization of the D-2(5/2) state and the quadratic
Zeeman coefficient in Yb-171(+)},
author = {T. R. Tan and C. L. Edmunds and A. R. Milne and M. J. Biercuk and C. Hempel},
doi = {10.1103/PhysRevA.104.L010802},
issn = {2469-9926},
year = {2021},
date = {2021-07-01},
journal = {PHYSICAL REVIEW A},
volume = {104},
number = {1},
abstract = {We report measurements of the branching fraction, hyperfine constant,
and second-order Zeeman coefficient of the D-5/2 level in Yb-171(+) with
up to a two-orders-of-magnitude reduction in uncertainty compared to
previously reported values. We estimate the electric quadrupole reduced
matrix element of the S-1/2 <-> D-5/2 transition to be 12.5(4) ea(0)(2).
Furthermore, we determine the transition frequency of the F-7/2 <->
D-1[3/2](3/2) at 760 nm with a similar to 25-fold improvement in
uncertainty. These measurements provide benchmarks for quantum-many-body
atomic-physics calculations and provide valuable data for efforts to
improve quantum information processors based on Yb-171(+).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report measurements of the branching fraction, hyperfine constant,
and second-order Zeeman coefficient of the D-5/2 level in Yb-171(+) with
up to a two-orders-of-magnitude reduction in uncertainty compared to
previously reported values. We estimate the electric quadrupole reduced
matrix element of the S-1/2 <-> D-5/2 transition to be 12.5(4) ea(0)(2).
Furthermore, we determine the transition frequency of the F-7/2 <->
D-1[3/2](3/2) at 760 nm with a similar to 25-fold improvement in
uncertainty. These measurements provide benchmarks for quantum-many-body
atomic-physics calculations and provide valuable data for efforts to
improve quantum information processors based on Yb-171(+).
and second-order Zeeman coefficient of the D-5/2 level in Yb-171(+) with
up to a two-orders-of-magnitude reduction in uncertainty compared to
previously reported values. We estimate the electric quadrupole reduced
matrix element of the S-1/2 <-> D-5/2 transition to be 12.5(4) ea(0)(2).
Furthermore, we determine the transition frequency of the F-7/2 <->
D-1[3/2](3/2) at 760 nm with a similar to 25-fold improvement in
uncertainty. These measurements provide benchmarks for quantum-many-body
atomic-physics calculations and provide valuable data for efforts to
improve quantum information processors based on Yb-171(+).
Edmunds, C. L.; Tan, T. R.; Milne, A. R.; Singh, A.; Biercuk, M. J.; Hempel, C.
Scalable hyperfine qubit state detection via electron shelving in the D-2(5/2) and F-2(7/2) manifolds in Yb-171(+) Journal Article
In: PHYSICAL REVIEW A, vol. 104, no. 1, 2021, ISSN: 2469-9926.
@article{WOS:000675546200005,
title = {Scalable hyperfine qubit state detection via electron shelving in the
D-2(5/2) and F-2(7/2) manifolds in Yb-171(+)},
author = {C. L. Edmunds and T. R. Tan and A. R. Milne and A. Singh and M. J. Biercuk and C. Hempel},
doi = {10.1103/PhysRevA.104.012606},
issn = {2469-9926},
year = {2021},
date = {2021-07-01},
journal = {PHYSICAL REVIEW A},
volume = {104},
number = {1},
abstract = {Qubits encoded in hyperfine states of trapped ions are ideal for quantum
computation given their long lifetimes and low sensitivity to magnetic
fields, yet they suffer from off-resonant scattering during detection,
often limiting their measurement fidelity. In Yb-171(+) this is
exacerbated by a low fluorescence yield, which leads to a need for
complex and expensive hardware, a problematic bottleneck especially when
scaling up the number of qubits. We demonstrate a detection routine
based on electron shelving to address this issue in Yb-171(+) and
achieve a 5.6x reduction in single-ion detection error on an avalanche
photodiode to 1.8(2) x 10(-3) in a 100 mu s detection period and a 4.3x
error reduction on an electron multiplying CCD camera with 7.7(2) x
10(-3) error in 400 mu s. We further improve the characterization of a
repump transition at 760 nm to enable a more rapid reset of the
auxiliary F-2(7/2) states populated after shelving. Finally, we examine
the detection fidelity limit using the long-lived F-2(7/2) state,
achieving further 300x and 12x reductions in error to 6(7) x 10(-6) and
6.3(3) x 10(-4) in 1 ms on the respective detectors. While shelving-rate
limited in our setup, we suggest various techniques to realize this
detection method at speeds compatible with quantum information
processing, providing a pathway to ultrahigh-fidelity detection in
Yb-171(+).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Qubits encoded in hyperfine states of trapped ions are ideal for quantum
computation given their long lifetimes and low sensitivity to magnetic
fields, yet they suffer from off-resonant scattering during detection,
often limiting their measurement fidelity. In Yb-171(+) this is
exacerbated by a low fluorescence yield, which leads to a need for
complex and expensive hardware, a problematic bottleneck especially when
scaling up the number of qubits. We demonstrate a detection routine
based on electron shelving to address this issue in Yb-171(+) and
achieve a 5.6x reduction in single-ion detection error on an avalanche
photodiode to 1.8(2) x 10(-3) in a 100 mu s detection period and a 4.3x
error reduction on an electron multiplying CCD camera with 7.7(2) x
10(-3) error in 400 mu s. We further improve the characterization of a
repump transition at 760 nm to enable a more rapid reset of the
auxiliary F-2(7/2) states populated after shelving. Finally, we examine
the detection fidelity limit using the long-lived F-2(7/2) state,
achieving further 300x and 12x reductions in error to 6(7) x 10(-6) and
6.3(3) x 10(-4) in 1 ms on the respective detectors. While shelving-rate
limited in our setup, we suggest various techniques to realize this
detection method at speeds compatible with quantum information
processing, providing a pathway to ultrahigh-fidelity detection in
Yb-171(+).
computation given their long lifetimes and low sensitivity to magnetic
fields, yet they suffer from off-resonant scattering during detection,
often limiting their measurement fidelity. In Yb-171(+) this is
exacerbated by a low fluorescence yield, which leads to a need for
complex and expensive hardware, a problematic bottleneck especially when
scaling up the number of qubits. We demonstrate a detection routine
based on electron shelving to address this issue in Yb-171(+) and
achieve a 5.6x reduction in single-ion detection error on an avalanche
photodiode to 1.8(2) x 10(-3) in a 100 mu s detection period and a 4.3x
error reduction on an electron multiplying CCD camera with 7.7(2) x
10(-3) error in 400 mu s. We further improve the characterization of a
repump transition at 760 nm to enable a more rapid reset of the
auxiliary F-2(7/2) states populated after shelving. Finally, we examine
the detection fidelity limit using the long-lived F-2(7/2) state,
achieving further 300x and 12x reductions in error to 6(7) x 10(-6) and
6.3(3) x 10(-4) in 1 ms on the respective detectors. While shelving-rate
limited in our setup, we suggest various techniques to realize this
detection method at speeds compatible with quantum information
processing, providing a pathway to ultrahigh-fidelity detection in
Yb-171(+).
Gupta, Riddhi Swaroop; Biercuk, Michael J.
Adaptive filtering of projective quantum measurements using discrete stochastic methods Journal Article
In: PHYSICAL REVIEW A, vol. 104, no. 1, 2021, ISSN: 2469-9926.
@article{WOS:000672757000002,
title = {Adaptive filtering of projective quantum measurements using discrete
stochastic methods},
author = {Riddhi Swaroop Gupta and Michael J. Biercuk},
doi = {10.1103/PhysRevA.104.012412},
issn = {2469-9926},
year = {2021},
date = {2021-07-01},
journal = {PHYSICAL REVIEW A},
volume = {104},
number = {1},
abstract = {Adaptive filtering is a powerful class of control theoretic concepts
useful in extracting information from noisy data sets or performing
forward prediction in time for a dynamic system. The broad utilization
of the associated algorithms makes them attractive targets for similar
problems in the quantum domain. To date, however, the construction of
adaptive filters for quantum systems has typically been carried out in
terms of stochastic differential equations for weak, continuous quantum
measurements, as used in linear quantum systems such as optical
cavities. Discretized measurement models are not as easily treated in
this framework, but are frequently employed in quantum information
systems leveraging projective measurements. This paper presents a
detailed analysis of several technical innovations that enable classical
filtering of discrete projective measurements, useful for adaptively
learning system dynamics, noise properties, or hardware performance
variations in classically correlated measurement data from quantum
devices. In previous work we studied a specific case of this framework,
in which noise and calibration errors on qubit arrays could be
efficiently characterized in space; here, we present a generalized
analysis of filtering in quantum systems and demonstrate that the
traditional convergence properties of nonlinear classical filtering hold
using single-shot projective measurements. These results are important
early demonstrations indicating that a range of concepts and techniques
from classical nonlinear filtering theory may be applied to the
characterization of quantum systems involving discretized projective
measurements, paving the way for broader adoption of control theoretic
techniques in quantum technology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Adaptive filtering is a powerful class of control theoretic concepts
useful in extracting information from noisy data sets or performing
forward prediction in time for a dynamic system. The broad utilization
of the associated algorithms makes them attractive targets for similar
problems in the quantum domain. To date, however, the construction of
adaptive filters for quantum systems has typically been carried out in
terms of stochastic differential equations for weak, continuous quantum
measurements, as used in linear quantum systems such as optical
cavities. Discretized measurement models are not as easily treated in
this framework, but are frequently employed in quantum information
systems leveraging projective measurements. This paper presents a
detailed analysis of several technical innovations that enable classical
filtering of discrete projective measurements, useful for adaptively
learning system dynamics, noise properties, or hardware performance
variations in classically correlated measurement data from quantum
devices. In previous work we studied a specific case of this framework,
in which noise and calibration errors on qubit arrays could be
efficiently characterized in space; here, we present a generalized
analysis of filtering in quantum systems and demonstrate that the
traditional convergence properties of nonlinear classical filtering hold
using single-shot projective measurements. These results are important
early demonstrations indicating that a range of concepts and techniques
from classical nonlinear filtering theory may be applied to the
characterization of quantum systems involving discretized projective
measurements, paving the way for broader adoption of control theoretic
techniques in quantum technology.
useful in extracting information from noisy data sets or performing
forward prediction in time for a dynamic system. The broad utilization
of the associated algorithms makes them attractive targets for similar
problems in the quantum domain. To date, however, the construction of
adaptive filters for quantum systems has typically been carried out in
terms of stochastic differential equations for weak, continuous quantum
measurements, as used in linear quantum systems such as optical
cavities. Discretized measurement models are not as easily treated in
this framework, but are frequently employed in quantum information
systems leveraging projective measurements. This paper presents a
detailed analysis of several technical innovations that enable classical
filtering of discrete projective measurements, useful for adaptively
learning system dynamics, noise properties, or hardware performance
variations in classically correlated measurement data from quantum
devices. In previous work we studied a specific case of this framework,
in which noise and calibration errors on qubit arrays could be
efficiently characterized in space; here, we present a generalized
analysis of filtering in quantum systems and demonstrate that the
traditional convergence properties of nonlinear classical filtering hold
using single-shot projective measurements. These results are important
early demonstrations indicating that a range of concepts and techniques
from classical nonlinear filtering theory may be applied to the
characterization of quantum systems involving discretized projective
measurements, paving the way for broader adoption of control theoretic
techniques in quantum technology.
MacDonell, Ryan J.; Dickerson, Claire E.; Birch, Clare J. T.; Kumar, Alok; Edmunds, Claire L.; Biercuk, Michael J.; Hempel, Cornelius; Kassal, Ivan
Analog quantum simulation of chemical dynamics Journal Article
In: CHEMICAL SCIENCE, vol. 12, no. 28, pp. 9794-9805, 2021, ISSN: 2041-6520.
@article{WOS:000665862400001,
title = {Analog quantum simulation of chemical dynamics},
author = {Ryan J. MacDonell and Claire E. Dickerson and Clare J. T. Birch and Alok Kumar and Claire L. Edmunds and Michael J. Biercuk and Cornelius Hempel and Ivan Kassal},
doi = {10.1039/d1sc02142g},
issn = {2041-6520},
year = {2021},
date = {2021-07-01},
journal = {CHEMICAL SCIENCE},
volume = {12},
number = {28},
pages = {9794-9805},
abstract = {Ultrafast chemical reactions are difficult to simulate because they
involve entangled, many-body wavefunctions whose computational
complexity grows rapidly with molecular size. In photochemistry, the
breakdown of the Born-Oppenheimer approximation further complicates the
problem by entangling nuclear and electronic degrees of freedom. Here,
we show that analog quantum simulators can efficiently simulate
molecular dynamics using commonly available bosonic modes to represent
molecular vibrations. Our approach can be implemented in any device with
a qudit controllably coupled to bosonic oscillators and with quantum
hardware resources that scale linearly with molecular size, and offers
significant resource savings compared to digital quantum simulation
algorithms. Advantages of our approach include a time resolution orders
of magnitude better than ultrafast spectroscopy, the ability to simulate
large molecules with limited hardware using a Suzuki-Trotter expansion,
and the ability to implement realistic system-bath interactions with
only one additional interaction per mode. Our approach can be
implemented with current technology; e.g., the conical intersection in
pyrazine can be simulated using a single trapped ion. Therefore, we
expect our method will enable classically intractable chemical dynamics
simulations in the near term.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ultrafast chemical reactions are difficult to simulate because they
involve entangled, many-body wavefunctions whose computational
complexity grows rapidly with molecular size. In photochemistry, the
breakdown of the Born-Oppenheimer approximation further complicates the
problem by entangling nuclear and electronic degrees of freedom. Here,
we show that analog quantum simulators can efficiently simulate
molecular dynamics using commonly available bosonic modes to represent
molecular vibrations. Our approach can be implemented in any device with
a qudit controllably coupled to bosonic oscillators and with quantum
hardware resources that scale linearly with molecular size, and offers
significant resource savings compared to digital quantum simulation
algorithms. Advantages of our approach include a time resolution orders
of magnitude better than ultrafast spectroscopy, the ability to simulate
large molecules with limited hardware using a Suzuki-Trotter expansion,
and the ability to implement realistic system-bath interactions with
only one additional interaction per mode. Our approach can be
implemented with current technology; e.g., the conical intersection in
pyrazine can be simulated using a single trapped ion. Therefore, we
expect our method will enable classically intractable chemical dynamics
simulations in the near term.
involve entangled, many-body wavefunctions whose computational
complexity grows rapidly with molecular size. In photochemistry, the
breakdown of the Born-Oppenheimer approximation further complicates the
problem by entangling nuclear and electronic degrees of freedom. Here,
we show that analog quantum simulators can efficiently simulate
molecular dynamics using commonly available bosonic modes to represent
molecular vibrations. Our approach can be implemented in any device with
a qudit controllably coupled to bosonic oscillators and with quantum
hardware resources that scale linearly with molecular size, and offers
significant resource savings compared to digital quantum simulation
algorithms. Advantages of our approach include a time resolution orders
of magnitude better than ultrafast spectroscopy, the ability to simulate
large molecules with limited hardware using a Suzuki-Trotter expansion,
and the ability to implement realistic system-bath interactions with
only one additional interaction per mode. Our approach can be
implemented with current technology; e.g., the conical intersection in
pyrazine can be simulated using a single trapped ion. Therefore, we
expect our method will enable classically intractable chemical dynamics
simulations in the near term.
Bland-Hawthorn, Joss; Sellars, Matthew J.; Bartholomew, J. G.
Quantum memories and the double-slit experiment: implications for astronomical interferometry Journal Article
In: Journal of the Optical Society of America B, vol. 38, no. 7, pp. A86, 2021, ISSN: 0740-3224.
@article{Bland-Hawthorn2021,
title = {Quantum memories and the double-slit experiment: implications for astronomical interferometry},
author = {Joss Bland-Hawthorn and Matthew J. Sellars and J. G. Bartholomew},
url = {https://www.osapublishing.org/viewmedia.cfm?uri=josab-38-7-A86&seq=0&html=true https://www.osapublishing.org/abstract.cfm?uri=josab-38-7-A86 https://www.osapublishing.org/josab/abstract.cfm?uri=josab-38-7-A86 https://www.osapublishing.org/abstract.cfm?URI},
doi = {10.1364/JOSAB.424651},
issn = {0740-3224},
year = {2021},
date = {2021-07-01},
journal = {Journal of the Optical Society of America B},
volume = {38},
number = {7},
pages = {A86},
publisher = {The Optical Society},
abstract = {Thomas Young's slit experiment lies at the heart of classical interference and quantum mechanics. Over the last fifty years, it has been shown that particles (e.g. photons, electrons, large molecules), even individual particles, generate an interference pattern at a distant screen after passage through a double slit, thereby demonstrating wave-particle duality. We revisit this famous experiment by replacing both slits with single-mode fibre inputs to two independent quantum memories that are capable of storing the incident electromagnetic field's amplitude and phase as a function of time. At a later time, the action is reversed: the quantum memories are read out in synchrony and the single-mode fibre outputs are allowed to interact consistent with the original observation. In contrast to any classical memory device, the write and read processes of a quantum memory are non-destructive and hence, preserve the photonic quantum states. In principle, with sufficiently long storage times and sufficiently high photonic storage capacity, quantum memories operating at widely separated telescopes can be brought together to achieve optical interferometry over arbitrarily long baselines.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Thomas Young's slit experiment lies at the heart of classical interference and quantum mechanics. Over the last fifty years, it has been shown that particles (e.g. photons, electrons, large molecules), even individual particles, generate an interference pattern at a distant screen after passage through a double slit, thereby demonstrating wave-particle duality. We revisit this famous experiment by replacing both slits with single-mode fibre inputs to two independent quantum memories that are capable of storing the incident electromagnetic field's amplitude and phase as a function of time. At a later time, the action is reversed: the quantum memories are read out in synchrony and the single-mode fibre outputs are allowed to interact consistent with the original observation. In contrast to any classical memory device, the write and read processes of a quantum memory are non-destructive and hence, preserve the photonic quantum states. In principle, with sufficiently long storage times and sufficiently high photonic storage capacity, quantum memories operating at widely separated telescopes can be brought together to achieve optical interferometry over arbitrarily long baselines.
Yoneda, J.; Huang, W.; Feng, M.; Yang, C. H.; Chan, K. W.; Tanttu, T.; Gilbert, W.; Leon, R. C. C.; Hudson, F. E.; Itoh, K. M.; Morello, A.; Bartlett, S. D.; Laucht, A.; Saraiva, A.; Dzurak, A. S.
Coherent spin qubit transport in silicon Journal Article
In: Nature Communications, vol. 12, no. 1, 2021, ISSN: 2041-1723.
BibTeX | Links:
@article{Yoneda_2021,
title = {Coherent spin qubit transport in silicon},
author = {J. Yoneda and W. Huang and M. Feng and C. H. Yang and K. W. Chan and T. Tanttu and W. Gilbert and R. C. C. Leon and F. E. Hudson and K. M. Itoh and A. Morello and S. D. Bartlett and A. Laucht and A. Saraiva and A. S. Dzurak},
url = {http://dx.doi.org/10.1038/s41467-021-24371-7},
doi = {10.1038/s41467-021-24371-7},
issn = {2041-1723},
year = {2021},
date = {2021-07-01},
journal = {Nature Communications},
volume = {12},
number = {1},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Milne, Alistair R.; Hempel, Cornelius; Li, Li; Edmunds, Claire L.; Slatyer, Harry J.; Ball, Harrison; Hush, Michael R.; Biercuk, Michael J.
Quantum Oscillator Noise Spectroscopy via Displaced Cat States Journal Article
In: PHYSICAL REVIEW LETTERS, vol. 126, no. 25, 2021, ISSN: 0031-9007.
@article{WOS:000669051600001,
title = {Quantum Oscillator Noise Spectroscopy via Displaced Cat States},
author = {Alistair R. Milne and Cornelius Hempel and Li Li and Claire L. Edmunds and Harry J. Slatyer and Harrison Ball and Michael R. Hush and Michael J. Biercuk},
doi = {10.1103/PhysRevLett.126.250506},
issn = {0031-9007},
year = {2021},
date = {2021-06-01},
journal = {PHYSICAL REVIEW LETTERS},
volume = {126},
number = {25},
abstract = {Quantum harmonic oscillators are central to many modem quantum
technologies. We introduce a method to determine the frequency noise
spectrum of oscillator modes through coupling them to a qubit with
continuously driven qubit-state-dependent displacements. We reconstruct
the noise spectrum using a series of different drive phase and amplitude
modulation patterns in conjunction with a data-fusion routine based on
convex optimization. We apply the technique to the identification of
intrinsic noise in the motional frequency of a single trapped ion with
sensitivity to fluctuations at the sub-Hz level in a spectral range from
quasi-dc up to 50 kHz.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Quantum harmonic oscillators are central to many modem quantum
technologies. We introduce a method to determine the frequency noise
spectrum of oscillator modes through coupling them to a qubit with
continuously driven qubit-state-dependent displacements. We reconstruct
the noise spectrum using a series of different drive phase and amplitude
modulation patterns in conjunction with a data-fusion routine based on
convex optimization. We apply the technique to the identification of
intrinsic noise in the motional frequency of a single trapped ion with
sensitivity to fluctuations at the sub-Hz level in a spectral range from
quasi-dc up to 50 kHz.
technologies. We introduce a method to determine the frequency noise
spectrum of oscillator modes through coupling them to a qubit with
continuously driven qubit-state-dependent displacements. We reconstruct
the noise spectrum using a series of different drive phase and amplitude
modulation patterns in conjunction with a data-fusion routine based on
convex optimization. We apply the technique to the identification of
intrinsic noise in the motional frequency of a single trapped ion with
sensitivity to fluctuations at the sub-Hz level in a spectral range from
quasi-dc up to 50 kHz.
King, Gavin G G; Barnett, Peter S; Bartholomew, J. G.; Faraon, Andrei; Longdell, Jevon J
Probing strong coupling between a microwave cavity and a spin ensemble with Raman heterodyne spectroscopy Journal Article
In: Physical Review B, vol. 103, no. 21, pp. 214305, 2021, ISSN: 2469-9950.
@article{King2021,
title = {Probing strong coupling between a microwave cavity and a spin ensemble with Raman heterodyne spectroscopy},
author = {Gavin G G King and Peter S Barnett and J. G. Bartholomew and Andrei Faraon and Jevon J Longdell},
url = {https://link.aps.org/doi/10.1103/PhysRevB.103.214305},
doi = {10.1103/PhysRevB.103.214305},
issn = {2469-9950},
year = {2021},
date = {2021-06-01},
journal = {Physical Review B},
volume = {103},
number = {21},
pages = {214305},
abstract = {Raman heterodyne spectroscopy is a powerful tool for characterizing the energy and dynamics of spins. The technique uses an optical pump to transfer coherence from a spin transition to an optical transition where the coherent emission is more easily detected. Here Raman heterodyne spectroscopy is used to probe an isotopically purified ensemble of erbium dopants in a yttrium orthosilicate (Y 2 SiO 5) crystal coupled to a microwave cavity. Because the erbium electron spin transition is strongly coupled to the microwave cavity, we observed Raman heterodyne signals at the resonant frequencies of the hybrid spin-cavity modes (polaritons) rather than the bare erbium spin-transition frequency. Using the coupled system, we made saturation recovery measurements of the ground-state spin relaxation time T 1 = 10 ± 3 s and also observed Raman heterodyne signals using an excited state spin transition. We discuss the implications of these results for efforts toward converting microwave quantum states to optical quantum states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Raman heterodyne spectroscopy is a powerful tool for characterizing the energy and dynamics of spins. The technique uses an optical pump to transfer coherence from a spin transition to an optical transition where the coherent emission is more easily detected. Here Raman heterodyne spectroscopy is used to probe an isotopically purified ensemble of erbium dopants in a yttrium orthosilicate (Y 2 SiO 5) crystal coupled to a microwave cavity. Because the erbium electron spin transition is strongly coupled to the microwave cavity, we observed Raman heterodyne signals at the resonant frequencies of the hybrid spin-cavity modes (polaritons) rather than the bare erbium spin-transition frequency. Using the coupled system, we made saturation recovery measurements of the ground-state spin relaxation time T 1 = 10 ± 3 s and also observed Raman heterodyne signals using an excited state spin transition. We discuss the implications of these results for efforts toward converting microwave quantum states to optical quantum states.
Grimsmo, Arne L.; Puri, Shruti
Quantum Error Correction with the Gottesman-Kitaev-Preskill Code Journal Article
In: PRX Quantum, vol. 2, no. 2, 2021, ISSN: 2691-3399.
BibTeX | Links:
@article{Grimsmo_2021,
title = {Quantum Error Correction with the Gottesman-Kitaev-Preskill Code},
author = {Arne L. Grimsmo and Shruti Puri},
url = {http://dx.doi.org/10.1103/PRXQuantum.2.020101},
doi = {10.1103/prxquantum.2.020101},
issn = {2691-3399},
year = {2021},
date = {2021-06-01},
journal = {PRX Quantum},
volume = {2},
number = {2},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tu, Bingsheng; Hahne, Felix; Arapoglou, Ioanna; Egl, Alexander; Heiße, Fabian; Höcker, Martin; König, Charlotte; Morgner, Jonathan; Sailer, Tim; Weigel, Andreas; Wolf, Robert; Sturm, Sven
Tank-Circuit Assisted Coupling Method for Sympathetic Laser Cooling Journal Article
In: Adv. Quantum Technol., pp. 2100029, 2021.
BibTeX | Links:
@article{Tu2021,
title = {Tank-Circuit Assisted Coupling Method for Sympathetic Laser Cooling},
author = {Bingsheng Tu and Felix Hahne and Ioanna Arapoglou and Alexander Egl and Fabian Heiße and Martin Höcker and Charlotte König and Jonathan Morgner and Tim Sailer and Andreas Weigel and Robert Wolf and Sven Sturm},
doi = {10.1002/qute.202100029},
year = {2021},
date = {2021-05-09},
urldate = {2021-05-09},
journal = {Adv. Quantum Technol.},
pages = {2100029},
publisher = {Wiley},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mougeot, M.; Atanasov, D.; Karthein, J.; Wolf, R. N.; Ascher, P.; Blaum, K.; Chrysalidis, K.; Hagen, G.; Holt, J. D.; Huang, W. J.; Jansen, G. R.; Kulikov, I.; Litvinov, Yu. A.; Lunney, D.; Manea, V.; Miyagi, T.; Papenbrock, T.; Schweikhard, L.; Schwenk, A.; Steinsberger, T.; Stroberg, S. R.; Sun, Z. H.; Welker, A.; Wienholtz, F.; Wilkins, S. G.; Zuber, K.
Mass measurements of 99–101In challenge ab initio nuclear theory of the nuclide 100Sn Journal Article
In: Nat. Phys., vol. 17, pp. 1099, 2021.
BibTeX | Links:
@article{Mougeot2021,
title = {Mass measurements of 99–101In challenge ab initio nuclear theory of the nuclide 100Sn},
author = {M. Mougeot and D. Atanasov and J. Karthein and R. N. Wolf and P. Ascher and K. Blaum and K. Chrysalidis and G. Hagen and J. D. Holt and W. J. Huang and G. R. Jansen and I. Kulikov and Yu. A. Litvinov and D. Lunney and V. Manea and T. Miyagi and T. Papenbrock and L. Schweikhard and A. Schwenk and T. Steinsberger and S. R. Stroberg and Z. H. Sun and A. Welker and F. Wienholtz and S. G. Wilkins and K. Zuber},
doi = {10.1038/s41567-021-01326-9},
year = {2021},
date = {2021-05-01},
journal = {Nat. Phys.},
volume = {17},
pages = {1099},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kojima, Y.; Nakajima, T.; Noiri, A.; Yoneda, J.; Otsuka, T.; Takeda, K.; Li, S.; Bartlett, S. D.; Ludwig, A.; Wieck, A. D.; Tarucha, S.
Probabilistic teleportation of a quantum dot spin qubit Journal Article
In: npj Quantum Information, vol. 7, no. 1, 2021, ISSN: 2056-6387.
BibTeX | Links:
@article{Kojima_2021,
title = {Probabilistic teleportation of a quantum dot spin qubit},
author = {Y. Kojima and T. Nakajima and A. Noiri and J. Yoneda and T. Otsuka and K. Takeda and S. Li and S. D. Bartlett and A. Ludwig and A. D. Wieck and S. Tarucha},
url = {http://dx.doi.org/10.1038/s41534-021-00403-4},
doi = {10.1038/s41534-021-00403-4},
issn = {2056-6387},
year = {2021},
date = {2021-05-01},
journal = {npj Quantum Information},
volume = {7},
number = {1},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Blais, Alexandre; Grimsmo, Arne L.; Girvin, S. M.; Wallraff, Andreas
Circuit quantum electrodynamics Journal Article
In: Reviews of Modern Physics, vol. 93, no. 2, 2021, ISSN: 1539-0756.
BibTeX | Links:
@article{Blais_2021,
title = {Circuit quantum electrodynamics},
author = {Alexandre Blais and Arne L. Grimsmo and S. M. Girvin and Andreas Wallraff},
url = {http://dx.doi.org/10.1103/RevModPhys.93.025005},
doi = {10.1103/revmodphys.93.025005},
issn = {1539-0756},
year = {2021},
date = {2021-05-01},
journal = {Reviews of Modern Physics},
volume = {93},
number = {2},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ataides, J. Pablo Bonilla; Tuckett, David K.; Bartlett, Stephen D.; Flammia, Steven T.; Brown, Benjamin J.
The XZZX surface code Journal Article
In: Nature Communications, vol. 12, no. 1, 2021, ISSN: 2041-1723.
BibTeX | Links:
@article{Bonilla_Ataides_2021,
title = {The XZZX surface code},
author = {J. Pablo Bonilla Ataides and David K. Tuckett and Stephen D. Bartlett and Steven T. Flammia and Benjamin J. Brown},
url = {http://dx.doi.org/10.1038/s41467-021-22274-1},
doi = {10.1038/s41467-021-22274-1},
issn = {2041-1723},
year = {2021},
date = {2021-04-01},
journal = {Nature Communications},
volume = {12},
number = {1},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Harper, Robin; Yu, Wenjun; Flammia, Steven T.
Fast Estimation of Sparse Quantum Noise Journal Article
In: PRX Quantum, vol. 2, no. 1, 2021, ISSN: 2691-3399.
BibTeX | Links:
@article{Harper_2021,
title = {Fast Estimation of Sparse Quantum Noise},
author = {Robin Harper and Wenjun Yu and Steven T. Flammia},
url = {http://dx.doi.org/10.1103/PRXQuantum.2.010322},
doi = {10.1103/prxquantum.2.010322},
issn = {2691-3399},
year = {2021},
date = {2021-02-01},
journal = {PRX Quantum},
volume = {2},
number = {1},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Craiciu, Ioana; Lei, Mi; Rochman, Jake; Bartholomew, J. G.; Faraon, Andrei
Multifunctional on-chip storage at telecommunication wavelength for quantum networks Journal Article
In: Optica, vol. 8, no. 1, pp. 114, 2021, ISSN: 2334-2536.
BibTeX | Links:
@article{Craiciu2021,
title = {Multifunctional on-chip storage at telecommunication wavelength for quantum networks},
author = {Ioana Craiciu and Mi Lei and Jake Rochman and J. G. Bartholomew and Andrei Faraon},
url = {https://www.osapublishing.org/abstract.cfm?URI=optica-8-1-114},
doi = {10.1364/OPTICA.412211},
issn = {2334-2536},
year = {2021},
date = {2021-01-01},
journal = {Optica},
volume = {8},
number = {1},
pages = {114},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Xie, Tian; Rochman, Jake; Bartholomew, J. G.; Ruskuc, Andrei; Kindem, Jonathan M; Craiciu, Ioana; Thiel, Charles W; Cone, Rufus L; Faraon, Andrei
Characterization of Er3+:YVO4 for microwave to optical transduction Journal Article
In: Physical Review B, vol. 104, no. 5, pp. 54111, 2021, ISSN: 2469-9950.
@article{Xie2021,
title = {Characterization of Er3+:YVO4 for microwave to optical transduction},
author = {Tian Xie and Jake Rochman and J. G. Bartholomew and Andrei Ruskuc and Jonathan M Kindem and Ioana Craiciu and Charles W Thiel and Rufus L Cone and Andrei Faraon},
doi = {10.1103/PhysRevB.104.054111},
issn = {2469-9950},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Physical Review B},
volume = {104},
number = {5},
pages = {54111},
abstract = {Quantum transduction between microwave and optical frequencies is important for connecting supercon-ducting quantum platforms within a quantum network. Ensembles of rare-earth ions are promising candidates to achieve this conversion due to their collective coherence properties at microwave and optical frequencies. Erbium ions are of particular interest because of their telecom wavelength optical transitions that are compatible with fiber communication networks and components. Here, we report the optical and electron spin properties of erbium-doped yttrium orthovanadate (Er 3+ :YVO 4), including high-resolution optical spectroscopy, electron paramagnetic resonance studies, and an initial demonstration of microwave to optical conversion of classical fields. The highly absorptive optical transitions and narrow ensemble linewidths make Er 3+ :YVO 4 promising for magneto-optic quantum transduction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Quantum transduction between microwave and optical frequencies is important for connecting supercon-ducting quantum platforms within a quantum network. Ensembles of rare-earth ions are promising candidates to achieve this conversion due to their collective coherence properties at microwave and optical frequencies. Erbium ions are of particular interest because of their telecom wavelength optical transitions that are compatible with fiber communication networks and components. Here, we report the optical and electron spin properties of erbium-doped yttrium orthovanadate (Er 3+ :YVO 4), including high-resolution optical spectroscopy, electron paramagnetic resonance studies, and an initial demonstration of microwave to optical conversion of classical fields. The highly absorptive optical transitions and narrow ensemble linewidths make Er 3+ :YVO 4 promising for magneto-optic quantum transduction.
Bardin, Joseph C; Slichter, Daniel H; Reilly, David J
Microwaves in quantum computing Journal Article
In: IEEE journal of microwaves, vol. 1, no. 1, pp. 403–427, 2021.
@article{bardin2021microwaves,
title = {Microwaves in quantum computing},
author = {Joseph C Bardin and Daniel H Slichter and David J Reilly},
year = {2021},
date = {2021-01-01},
journal = {IEEE journal of microwaves},
volume = {1},
number = {1},
pages = {403--427},
publisher = {IEEE},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Laucht, Arne; Hohls, Frank; Ubbelohde, Niels; Gonzalez-Zalba, M Fernando; Reilly, David J; Stobbe, Søren; Schröder, Tim; Scarlino, Pasquale; Koski, Jonne V; Dzurak, Andrew; others,
Roadmap on quantum nanotechnologies Journal Article
In: Nanotechnology, vol. 32, no. 16, pp. 162003, 2021.
@article{laucht2021roadmap,
title = {Roadmap on quantum nanotechnologies},
author = {Arne Laucht and Frank Hohls and Niels Ubbelohde and M Fernando Gonzalez-Zalba and David J Reilly and Søren Stobbe and Tim Schröder and Pasquale Scarlino and Jonne V Koski and Andrew Dzurak and others},
year = {2021},
date = {2021-01-01},
journal = {Nanotechnology},
volume = {32},
number = {16},
pages = {162003},
publisher = {IOP Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hasler, Jennifer; Dick, Neil; Das, Kushal; Degnan, Brian; Moini, Alireza; Reilly, David
Cryogenic floating-gate CMOS circuits for quantum control Journal Article
In: IEEE Transactions on Quantum Engineering, vol. 2, pp. 1–10, 2021.
@article{hasler2021cryogenic,
title = {Cryogenic floating-gate CMOS circuits for quantum control},
author = {Jennifer Hasler and Neil Dick and Kushal Das and Brian Degnan and Alireza Moini and David Reilly},
year = {2021},
date = {2021-01-01},
journal = {IEEE Transactions on Quantum Engineering},
volume = {2},
pages = {1--10},
publisher = {IEEE},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
Bartholomew, J. G.; Rochman, Jake; Xie, Tian; Kindem, Jonathan M.; Ruskuc, Andrei; Craiciu, Ioana; Lei, Mi; Faraon, Andrei
On-chip coherent microwave-to-optical transduction mediated by ytterbium in YVO4 Journal Article
In: Nature Communications, vol. 11, no. 1, pp. 3266, 2020, ISSN: 2041-1723.
@article{Bartholomew2020,
title = {On-chip coherent microwave-to-optical transduction mediated by ytterbium in YVO4},
author = {J. G. Bartholomew and Jake Rochman and Tian Xie and Jonathan M. Kindem and Andrei Ruskuc and Ioana Craiciu and Mi Lei and Andrei Faraon},
url = {http://www.nature.com/articles/s41467-020-16996-x},
doi = {10.1038/s41467-020-16996-x},
issn = {2041-1723},
year = {2020},
date = {2020-12-01},
journal = {Nature Communications},
volume = {11},
number = {1},
pages = {3266},
publisher = {Nature Publishing Group},
abstract = {Optical networks that distribute entanglement among various quantum systems will form a powerful framework for quantum science but are yet to interface with leading quantum hardware such as superconducting qubits. Consequently, these systems remain isolated because microwave links at room temperature are noisy and lossy. Building long distance connectivity requires interfaces that map quantum information between microwave and optical fields. While preliminary microwave-to-optical transducers have been realized, developing efficient, low-noise devices that match superconducting qubit frequencies (gigahertz) and bandwidths (10 kilohertz – 1 megahertz) remains a challenge. Here we demonstrate a proof-of-concept on-chip transducer using trivalent ytterbium-171 ions in yttrium orthovanadate coupled to a nanophotonic waveguide and a microwave transmission line. The device′s miniaturization, material, and zero-magnetic-field operation are important advances for rare-earth ion magneto-optical devices. Further integration with high quality factor microwave and optical resonators will enable efficient transduction and create opportunities toward multi-platform quantum networks. Long distance interfaces between superconducting quantum information processing nodes would require coherent, efficient and low-noise microwave-to-optical conversion. Here, the authors use Yb ion ensembles in yttrium orthovanadate to demonstrate a transducer with the potential to fulfill these requirements.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Optical networks that distribute entanglement among various quantum systems will form a powerful framework for quantum science but are yet to interface with leading quantum hardware such as superconducting qubits. Consequently, these systems remain isolated because microwave links at room temperature are noisy and lossy. Building long distance connectivity requires interfaces that map quantum information between microwave and optical fields. While preliminary microwave-to-optical transducers have been realized, developing efficient, low-noise devices that match superconducting qubit frequencies (gigahertz) and bandwidths (10 kilohertz – 1 megahertz) remains a challenge. Here we demonstrate a proof-of-concept on-chip transducer using trivalent ytterbium-171 ions in yttrium orthovanadate coupled to a nanophotonic waveguide and a microwave transmission line. The device′s miniaturization, material, and zero-magnetic-field operation are important advances for rare-earth ion magneto-optical devices. Further integration with high quality factor microwave and optical resonators will enable efficient transduction and create opportunities toward multi-platform quantum networks. Long distance interfaces between superconducting quantum information processing nodes would require coherent, efficient and low-noise microwave-to-optical conversion. Here, the authors use Yb ion ensembles in yttrium orthovanadate to demonstrate a transducer with the potential to fulfill these requirements.
Bardin, Joseph C; Slichter, Daniel H; Reilly, David J
Microwaves in Quantum Computing Journal Article
In: arXiv preprint arXiv:2011.01480, 2020.
BibTeX | Links:
@article{bardin2020microwaves,
title = {Microwaves in Quantum Computing},
author = {Joseph C Bardin and Daniel H Slichter and David J Reilly},
url = {https://arxiv.org/abs/2011.01480},
year = {2020},
date = {2020-11-03},
journal = {arXiv preprint arXiv:2011.01480},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carvalho, Andre RR; Ball, Harrison; Biercuk, Michael J; Hush, Michael R; Thomsen, Felix
Error-robust quantum logic optimization using a cloud quantum computer interface Journal Article
In: arXiv preprint arXiv:2010.08057, 2020.
BibTeX | Links:
@article{carvalho2020error,
title = {Error-robust quantum logic optimization using a cloud quantum computer interface},
author = {Andre RR Carvalho and Harrison Ball and Michael J Biercuk and Michael R Hush and Felix Thomsen},
url = {https://arxiv.org/abs/2010.08057},
year = {2020},
date = {2020-10-15},
journal = {arXiv preprint arXiv:2010.08057},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Gupta, Riddhi Swaroop; Govia, Luke C. G.; Biercuk, Michael J.
Integration of spectator qubits into quantum computer architectures for hardware tune-up and calibration Journal Article
In: PHYSICAL REVIEW A, vol. 102, no. 4, 2020, ISSN: 2469-9926.
@article{WOS:000580591500005,
title = {Integration of spectator qubits into quantum computer architectures for
hardware tune-up and calibration},
author = {Riddhi Swaroop Gupta and Luke C. G. Govia and Michael J. Biercuk},
doi = {10.1103/PhysRevA.102.042611},
issn = {2469-9926},
year = {2020},
date = {2020-10-01},
journal = {PHYSICAL REVIEW A},
volume = {102},
number = {4},
abstract = {Performing efficient quantum computer tune-up and calibration is
essential for growth in system complexity. In this work we explore the
link between facilitating such capabilities and the underlying
architecture of the physical hardware. We focus on the specific
challenge of measuring (''mapping'') spatially inhomogeneous
quasistatic calibration errors using spectator qubits dedicated to the
task of sensing and calibration. We introduce an architectural concept
for such spectator qubits: arranging them spatially according to
prescriptions from optimal two-dimensional approximation theory. We show
that this insight allows for efficient reconstruction of inhomogeneities
in qubit calibration, focusing on the specific example of frequency
errors which may arise from fabrication variances or ambient magnetic
fields. Our results demonstrate that optimal interpolation techniques
display near optimal error scaling in cases where the measured
characteristic (here the qubit frequency) varies smoothly, and we probe
the limits of these benefits as a function of measurement uncertainty.
For more complex spatial variations, we demonstrate that the noise
mapping for quantum architectures formalism for adaptive measurement and
noise filtering outperforms optimal interpolation techniques in
isolation and, crucially, can be combined with insights from optimal
interpolation theory to produce a general purpose protocol.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Performing efficient quantum computer tune-up and calibration is
essential for growth in system complexity. In this work we explore the
link between facilitating such capabilities and the underlying
architecture of the physical hardware. We focus on the specific
challenge of measuring (''mapping'') spatially inhomogeneous
quasistatic calibration errors using spectator qubits dedicated to the
task of sensing and calibration. We introduce an architectural concept
for such spectator qubits: arranging them spatially according to
prescriptions from optimal two-dimensional approximation theory. We show
that this insight allows for efficient reconstruction of inhomogeneities
in qubit calibration, focusing on the specific example of frequency
errors which may arise from fabrication variances or ambient magnetic
fields. Our results demonstrate that optimal interpolation techniques
display near optimal error scaling in cases where the measured
characteristic (here the qubit frequency) varies smoothly, and we probe
the limits of these benefits as a function of measurement uncertainty.
For more complex spatial variations, we demonstrate that the noise
mapping for quantum architectures formalism for adaptive measurement and
noise filtering outperforms optimal interpolation techniques in
isolation and, crucially, can be combined with insights from optimal
interpolation theory to produce a general purpose protocol.
essential for growth in system complexity. In this work we explore the
link between facilitating such capabilities and the underlying
architecture of the physical hardware. We focus on the specific
challenge of measuring (''mapping'') spatially inhomogeneous
quasistatic calibration errors using spectator qubits dedicated to the
task of sensing and calibration. We introduce an architectural concept
for such spectator qubits: arranging them spatially according to
prescriptions from optimal two-dimensional approximation theory. We show
that this insight allows for efficient reconstruction of inhomogeneities
in qubit calibration, focusing on the specific example of frequency
errors which may arise from fabrication variances or ambient magnetic
fields. Our results demonstrate that optimal interpolation techniques
display near optimal error scaling in cases where the measured
characteristic (here the qubit frequency) varies smoothly, and we probe
the limits of these benefits as a function of measurement uncertainty.
For more complex spatial variations, we demonstrate that the noise
mapping for quantum architectures formalism for adaptive measurement and
noise filtering outperforms optimal interpolation techniques in
isolation and, crucially, can be combined with insights from optimal
interpolation theory to produce a general purpose protocol.
Warszawski, Prahlad; Wiseman, Howard M.; Doherty, Andrew C.
Solving quantum trajectories for systems with linear Heisenberg-picture dynamics and Gaussian measurement noise Journal Article
In: Physical Review A, vol. 102, no. 4, 2020, ISSN: 2469-9934.
BibTeX | Links:
@article{Warszawski_2020,
title = {Solving quantum trajectories for systems with linear Heisenberg-picture dynamics and Gaussian measurement noise},
author = {Prahlad Warszawski and Howard M. Wiseman and Andrew C. Doherty},
url = {http://dx.doi.org/10.1103/PhysRevA.102.042210},
doi = {10.1103/physreva.102.042210},
issn = {2469-9934},
year = {2020},
date = {2020-10-01},
journal = {Physical Review A},
volume = {102},
number = {4},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pauka, SJ; Witt, JDS; Allen, CN; Harlech-Jones, B; Jouan, A; Gardner, GC; Gronin, S; Wang, T; Thomas, C; Manfra, MJ; others,
Repairing the surface of InAs-based topological heterostructures Journal Article
In: Journal of Applied Physics, vol. 128, no. 11, pp. 114301, 2020.
BibTeX | Links:
@article{pauka2020repairing,
title = {Repairing the surface of InAs-based topological heterostructures},
author = {SJ Pauka and JDS Witt and CN Allen and B Harlech-Jones and A Jouan and GC Gardner and S Gronin and T Wang and C Thomas and MJ Manfra and others},
url = {https://aip.scitation.org/doi/abs/10.1063/5.0014361},
year = {2020},
date = {2020-09-21},
journal = {Journal of Applied Physics},
volume = {128},
number = {11},
pages = {114301},
publisher = {AIP Publishing LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Girdhar, Parth; Doherty, Andrew C
Testing generalised uncertainty principles through quantum noise Journal Article
In: New Journal of Physics, vol. 22, no. 9, pp. 093073, 2020, ISSN: 1367-2630.
BibTeX | Links:
@article{Girdhar_2020,
title = {Testing generalised uncertainty principles through quantum noise},
author = {Parth Girdhar and Andrew C Doherty},
url = {http://dx.doi.org/10.1088/1367-2630/abb43c},
doi = {10.1088/1367-2630/abb43c},
issn = {1367-2630},
year = {2020},
date = {2020-09-01},
journal = {New Journal of Physics},
volume = {22},
number = {9},
pages = {093073},
publisher = {IOP Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Frey, Virginia; Norris, Leigh M.; Viola, Lorenza; Biercuk, Michael J.
Simultaneous Spectral Estimation of Dephasing and Amplitude Noise on a Qubit Sensor via Optimally Band-Limited Control Journal Article
In: PHYSICAL REVIEW APPLIED, vol. 14, no. 2, 2020, ISSN: 2331-7019.
@article{WOS:000559297800001,
title = {Simultaneous Spectral Estimation of Dephasing and Amplitude Noise on a
Qubit Sensor via Optimally Band-Limited Control},
author = {Virginia Frey and Leigh M. Norris and Lorenza Viola and Michael J. Biercuk},
doi = {10.1103/PhysRevApplied.14.024021},
issn = {2331-7019},
year = {2020},
date = {2020-08-01},
journal = {PHYSICAL REVIEW APPLIED},
volume = {14},
number = {2},
abstract = {The fragility of quantum systems makes them ideally suited for sensing
applications at the nanoscale. However, interpreting the output signal
of a qubit-based sensor is generally complicated by background clutter
due to out-of-band spectral leakage, as well as ambiguity in signal
origin when the sensor is operated with noisy hardware. We present a
sensing protocol based on optimally band-limited ``Slepian functions''
that can overcome these challenges, by providing narrowband sensing of
ambient dephasing noise, coupling additively to the sensor along the z
axis, while permitting isolation of the target noise spectrum from other
contributions coupling along a different axis. This is achieved by
introducing a finite-difference control modulation, which linearizes the
sensor's response and affords tunable band-limited ``windowing'' in
frequency. Building on these techniques, we experimentally demonstrate
two spectral estimation capabilities using a trapped-ion qubit sensor.
We first perform efficient experimental reconstruction of a ``mixed''
dephasing spectrum, composed of a broadband 1/f -type spectrum with
discrete spurs. We then demonstrate the simultaneous reconstruction of
overlapping dephasing and control noise spectra from a single set of
measurements, in a setting where the two noise sources contribute
equally to the sensor's response. Our approach provides a direct means
to augment quantum-sensor performance in the presence of both complex
broadband noise environments and imperfect control signals, by optimally
complying with realistic time-bandwidth constraints.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The fragility of quantum systems makes them ideally suited for sensing
applications at the nanoscale. However, interpreting the output signal
of a qubit-based sensor is generally complicated by background clutter
due to out-of-band spectral leakage, as well as ambiguity in signal
origin when the sensor is operated with noisy hardware. We present a
sensing protocol based on optimally band-limited ``Slepian functions''
that can overcome these challenges, by providing narrowband sensing of
ambient dephasing noise, coupling additively to the sensor along the z
axis, while permitting isolation of the target noise spectrum from other
contributions coupling along a different axis. This is achieved by
introducing a finite-difference control modulation, which linearizes the
sensor's response and affords tunable band-limited ``windowing'' in
frequency. Building on these techniques, we experimentally demonstrate
two spectral estimation capabilities using a trapped-ion qubit sensor.
We first perform efficient experimental reconstruction of a ``mixed''
dephasing spectrum, composed of a broadband 1/f -type spectrum with
discrete spurs. We then demonstrate the simultaneous reconstruction of
overlapping dephasing and control noise spectra from a single set of
measurements, in a setting where the two noise sources contribute
equally to the sensor's response. Our approach provides a direct means
to augment quantum-sensor performance in the presence of both complex
broadband noise environments and imperfect control signals, by optimally
complying with realistic time-bandwidth constraints.
applications at the nanoscale. However, interpreting the output signal
of a qubit-based sensor is generally complicated by background clutter
due to out-of-band spectral leakage, as well as ambiguity in signal
origin when the sensor is operated with noisy hardware. We present a
sensing protocol based on optimally band-limited ``Slepian functions''
that can overcome these challenges, by providing narrowband sensing of
ambient dephasing noise, coupling additively to the sensor along the z
axis, while permitting isolation of the target noise spectrum from other
contributions coupling along a different axis. This is achieved by
introducing a finite-difference control modulation, which linearizes the
sensor's response and affords tunable band-limited ``windowing'' in
frequency. Building on these techniques, we experimentally demonstrate
two spectral estimation capabilities using a trapped-ion qubit sensor.
We first perform efficient experimental reconstruction of a ``mixed''
dephasing spectrum, composed of a broadband 1/f -type spectrum with
discrete spurs. We then demonstrate the simultaneous reconstruction of
overlapping dephasing and control noise spectra from a single set of
measurements, in a setting where the two noise sources contribute
equally to the sensor's response. Our approach provides a direct means
to augment quantum-sensor performance in the presence of both complex
broadband noise environments and imperfect control signals, by optimally
complying with realistic time-bandwidth constraints.
Gupta, Riddhi Swaroop; Edmunds, Claire L; Milne, Alistair R; Hempel, Cornelius; Biercuk, Michael J
Adaptive characterization of spatially inhomogeneous fields and errors in qubit registers Journal Article
In: npj Quantum Information, vol. 6, no. 1, pp. 53, 2020.
@article{Gupta.2020,
title = {Adaptive characterization of spatially inhomogeneous fields and errors in qubit registers},
author = {Riddhi Swaroop Gupta and Claire L Edmunds and Alistair R Milne and Cornelius Hempel and Michael J Biercuk},
doi = {10.1038/s41534-020-0286-0},
year = {2020},
date = {2020-06-12},
journal = {npj Quantum Information},
volume = {6},
number = {1},
pages = {53},
abstract = {New quantum computing architectures consider integrating qubits as sensors to provide actionable information useful for calibration or decoherence mitigation on neighboring data qubits, but little work has addressed how such schemes may be efficiently implemented in order to maximize information utilization. Techniques from classical estimation and dynamic control, suitably adapted to the strictures of quantum measurement, provide an opportunity to extract augmented hardware performance through automation of low-level characterization and control. In this work, we present an adaptive learning framework, Noise Mapping for Quantum Architectures (NMQA), for scheduling of sensor–qubit measurements and efficient spatial noise mapping (prior to actuation) across device architectures. Via a two-layer particle filter, NMQA receives binary measurements and determines regions within the architecture that share common noise processes; an adaptive controller then schedules future measurements to reduce map uncertainty. Numerical analysis and experiments on an array of trapped ytterbium ions demonstrate that NMQA outperforms brute-force mapping by up to 20× (3×) in simulations (experiments), calculated as a reduction in the number of measurements required to map a spatially inhomogeneous magnetic field with a target error metric. As an early adaptation of robotic control to quantum devices, this work opens up exciting new avenues in quantum computer science.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
New quantum computing architectures consider integrating qubits as sensors to provide actionable information useful for calibration or decoherence mitigation on neighboring data qubits, but little work has addressed how such schemes may be efficiently implemented in order to maximize information utilization. Techniques from classical estimation and dynamic control, suitably adapted to the strictures of quantum measurement, provide an opportunity to extract augmented hardware performance through automation of low-level characterization and control. In this work, we present an adaptive learning framework, Noise Mapping for Quantum Architectures (NMQA), for scheduling of sensor–qubit measurements and efficient spatial noise mapping (prior to actuation) across device architectures. Via a two-layer particle filter, NMQA receives binary measurements and determines regions within the architecture that share common noise processes; an adaptive controller then schedules future measurements to reduce map uncertainty. Numerical analysis and experiments on an array of trapped ytterbium ions demonstrate that NMQA outperforms brute-force mapping by up to 20× (3×) in simulations (experiments), calculated as a reduction in the number of measurements required to map a spatially inhomogeneous magnetic field with a target error metric. As an early adaptation of robotic control to quantum devices, this work opens up exciting new avenues in quantum computer science.
Marciniak, Ch. D; Rischka, A; Wolf, R N; Biercuk, M J
High-power spectral beamsplitter for closely spaced frequencies Journal Article
In: Optics Express, vol. 28, no. 8, pp. 11372, 2020.
BibTeX | Links:
@article{Marciniak2020,
title = {High-power spectral beamsplitter for closely spaced frequencies},
author = {Ch. D Marciniak and A Rischka and R N Wolf and M J Biercuk},
doi = {10.1364/oe.390956},
year = {2020},
date = {2020-04-01},
journal = {Optics Express},
volume = {28},
number = {8},
pages = {11372},
publisher = {The Optical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kindem, Jonathan M.; Ruskuc, Andrei; Bartholomew, J. G.; Rochman, Jake; Huan, Yan Qi; Faraon, Andrei
Control and single-shot readout of an ion embedded in a nanophotonic cavity Journal Article
In: Nature, vol. 580, no. 7802, pp. 201–204, 2020, ISSN: 0028-0836.
BibTeX | Links:
@article{Kindem2020,
title = {Control and single-shot readout of an ion embedded in a nanophotonic cavity},
author = {Jonathan M. Kindem and Andrei Ruskuc and J. G. Bartholomew and Jake Rochman and Yan Qi Huan and Andrei Faraon},
url = {http://www.nature.com/articles/s41586-020-2160-9},
doi = {10.1038/s41586-020-2160-9},
issn = {0028-0836},
year = {2020},
date = {2020-04-01},
journal = {Nature},
volume = {580},
number = {7802},
pages = {201--204},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Edmunds, C L; Hempel, C; Harris, R J; Frey, V; Stace, T M; Biercuk, M J
Dynamically corrected gates suppressing spatiotemporal error correlations as measured by randomized benchmarking Journal Article
In: Physical Review Research, vol. 2, no. 1, pp. 013156, 2020.
@article{Edmunds.2020,
title = {Dynamically corrected gates suppressing spatiotemporal error correlations as measured by randomized benchmarking},
author = {C L Edmunds and C Hempel and R J Harris and V Frey and T M Stace and M J Biercuk},
doi = {10.1103/physrevresearch.2.013156},
year = {2020},
date = {2020-01-01},
journal = {Physical Review Research},
volume = {2},
number = {1},
pages = {013156},
abstract = {Quantum error correction provides a path to large-scale quantum computers, but is built on challenging assumptions about the characteristics of the underlying errors. In particular, the mathematical assumption of statistically independent errors in quantum logic operations is at odds with realistic environments where error sources may exhibit strong temporal and spatial correlations. We present experiments using trapped ions to demonstrate that the use of dynamically corrected gates (DCGs), generally considered for the reduction of error magnitudes, can also suppress error correlations in space and time throughout quantum circuits. We present a first-principles analysis of the manifestation of error correlations in randomized benchmarking and validate this model through experiments performed using engineered errors. We find that standard DCGs can reduce error correlations by ∼50× while increasing the magnitude of uncorrelated errors by a factor scaling linearly with the extended DCG duration compared to a primitive gate. We then demonstrate that the correlation characteristics of intrinsic errors in our system are modified by the use of DCGs, consistent with a picture in which DCGs whiten the effective error spectrum induced by external noise.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Quantum error correction provides a path to large-scale quantum computers, but is built on challenging assumptions about the characteristics of the underlying errors. In particular, the mathematical assumption of statistically independent errors in quantum logic operations is at odds with realistic environments where error sources may exhibit strong temporal and spatial correlations. We present experiments using trapped ions to demonstrate that the use of dynamically corrected gates (DCGs), generally considered for the reduction of error magnitudes, can also suppress error correlations in space and time throughout quantum circuits. We present a first-principles analysis of the manifestation of error correlations in randomized benchmarking and validate this model through experiments performed using engineered errors. We find that standard DCGs can reduce error correlations by ∼50× while increasing the magnitude of uncorrelated errors by a factor scaling linearly with the extended DCG duration compared to a primitive gate. We then demonstrate that the correlation characteristics of intrinsic errors in our system are modified by the use of DCGs, consistent with a picture in which DCGs whiten the effective error spectrum induced by external noise.
Bentley, Christopher D B; Ball, Harrison; Biercuk, Michael J; Carvalho, Andre R R; Hush, Michael R; Slatyer, Harry J
Numeric Optimization for Configurable, Parallel, Error‐Robust Entangling Gates in Large Ion Registers Journal Article
In: Advanced Quantum Technologies, pp. 2000044, 2020, ISSN: 2511-9044.
@article{Bentley.2020,
title = {Numeric Optimization for Configurable, Parallel, Error‐Robust Entangling Gates in Large Ion Registers},
author = {Christopher D B Bentley and Harrison Ball and Michael J Biercuk and Andre R R Carvalho and Michael R Hush and Harry J Slatyer},
doi = {10.1002/qute.202000044},
issn = {2511-9044},
year = {2020},
date = {2020-01-01},
journal = {Advanced Quantum Technologies},
pages = {2000044},
abstract = {A class of entangling gates for trapped atomic ions is studied and the use of numeric optimization techniques to create a wide range of fast, error‐robust gate constructions is demonstrated. A numeric optimization framework is introduced targeting maximally‐ and partially‐entangling operations on ion pairs, multi‐ion registers, multi‐ion subsets of large registers, and parallel operations within a single register. Ions are assumed to be individually addressed, permitting optimization over amplitude‐ and phase‐modulated controls. Calculations and simulations demonstrate that the inclusion of modulation of the difference phase for the bichromatic drive used in the Mølmer–Sørensen gate permits approximately time‐optimal control across a range of gate configurations, and when suitably combined with analytic constraints can also provide robustness against key experimental sources of error. The impact of experimental constraints such as bounds on coupling rates or modulation band‐limits on achievable performance is further demonstrated. Using a custom optimization engine based on TensorFlow, for optimizations on ion registers up to 20 ions, time‐to‐solution of order tens of minutes using a local‐instance laptop is also demonstrated, allowing computational access to system‐scales relevant to near‐term trapped‐ion devices. Numeric optimization and control techniques are demonstrated to create a wide range of fast, robust, high‐fidelity gates. Complex drive controls, with both phase and amplitude modulation on the mediating laser field, are applied to enact multi‐body and parallel operations on chains of up to 20 ions. Control solutions incorporate real constraints on modulation hardware and robustness to laser noise sources.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A class of entangling gates for trapped atomic ions is studied and the use of numeric optimization techniques to create a wide range of fast, error‐robust gate constructions is demonstrated. A numeric optimization framework is introduced targeting maximally‐ and partially‐entangling operations on ion pairs, multi‐ion registers, multi‐ion subsets of large registers, and parallel operations within a single register. Ions are assumed to be individually addressed, permitting optimization over amplitude‐ and phase‐modulated controls. Calculations and simulations demonstrate that the inclusion of modulation of the difference phase for the bichromatic drive used in the Mølmer–Sørensen gate permits approximately time‐optimal control across a range of gate configurations, and when suitably combined with analytic constraints can also provide robustness against key experimental sources of error. The impact of experimental constraints such as bounds on coupling rates or modulation band‐limits on achievable performance is further demonstrated. Using a custom optimization engine based on TensorFlow, for optimizations on ion registers up to 20 ions, time‐to‐solution of order tens of minutes using a local‐instance laptop is also demonstrated, allowing computational access to system‐scales relevant to near‐term trapped‐ion devices. Numeric optimization and control techniques are demonstrated to create a wide range of fast, robust, high‐fidelity gates. Complex drive controls, with both phase and amplitude modulation on the mediating laser field, are applied to enact multi‐body and parallel operations on chains of up to 20 ions. Control solutions incorporate real constraints on modulation hardware and robustness to laser noise sources.
Milne, Alistair R; Edmunds, Claire L; Hempel, Cornelius; Roy, Federico; Mavadia, Sandeep; Biercuk, Michael J
Phase-Modulated Entangling Gates Robust to Static and Time-Varying Errors Journal Article
In: Physical Review Applied, vol. 13, no. 2, pp. 024022, 2020.
@article{Milne.2020,
title = {Phase-Modulated Entangling Gates Robust to Static and Time-Varying Errors},
author = {Alistair R Milne and Claire L Edmunds and Cornelius Hempel and Federico Roy and Sandeep Mavadia and Michael J Biercuk},
doi = {10.1103/physrevapplied.13.024022},
year = {2020},
date = {2020-01-01},
journal = {Physical Review Applied},
volume = {13},
number = {2},
pages = {024022},
abstract = {Entangling operations are among the most important primitive gates employed in quantum computing, and it is crucial to ensure high-fidelity implementations as systems are scaled up. We experimentally realize and characterize a simple scheme to minimize errors in entangling operations related to the residual excitation of mediating bosonic oscillator modes that both improves gate robustness and provides scaling benefits in larger systems. The technique employs discrete phase shifts in the control field driving the gate operation, determined either analytically or numerically, to ensure all modes are de-excited at arbitrary user-defined times. We demonstrate an average gate fidelity of 99.4(2)% across a wide range of parameters in a system of Yb171+ trapped ion qubits, and observe a reduction of gate error in the presence of common experimental error sources. Our approach provides a unified framework to achieve robustness against both static and time-varying laser amplitude and frequency detuning errors. We verify these capabilities through system-identification experiments revealing improvements in error susceptibility achieved in phase-modulated gates.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Entangling operations are among the most important primitive gates employed in quantum computing, and it is crucial to ensure high-fidelity implementations as systems are scaled up. We experimentally realize and characterize a simple scheme to minimize errors in entangling operations related to the residual excitation of mediating bosonic oscillator modes that both improves gate robustness and provides scaling benefits in larger systems. The technique employs discrete phase shifts in the control field driving the gate operation, determined either analytically or numerically, to ensure all modes are de-excited at arbitrary user-defined times. We demonstrate an average gate fidelity of 99.4(2)% across a wide range of parameters in a system of Yb171+ trapped ion qubits, and observe a reduction of gate error in the presence of common experimental error sources. Our approach provides a unified framework to achieve robustness against both static and time-varying laser amplitude and frequency detuning errors. We verify these capabilities through system-identification experiments revealing improvements in error susceptibility achieved in phase-modulated gates.
Ball, Harrison; Biercuk, Michael J; Carvalho, Andre; Chen, Jiayin; Hush, Michael; Castro, Leonardo De A; Li, Li; Liebermann, Per J; Slatyer, Harry J; Edmunds, Claire; Frey, Virginia; Hempel, Cornelius; Milne, Alistair
Software tools for quantum control: Improving quantum computer performance through noise and error suppression Journal Article
In: arXiv, vol. quant-ph, no. 2001.04060, 2020.
@article{ball2020software,
title = {Software tools for quantum control: Improving quantum computer performance through noise and error suppression},
author = {Harrison Ball and Michael J Biercuk and Andre Carvalho and Jiayin Chen and Michael Hush and Leonardo De A Castro and Li Li and Per J Liebermann and Harry J Slatyer and Claire Edmunds and Virginia Frey and Cornelius Hempel and Alistair Milne},
url = {https://arxiv.org/abs/2001.04060},
year = {2020},
date = {2020-01-01},
journal = {arXiv},
volume = {quant-ph},
number = {2001.04060},
abstract = {Manipulating quantum computing hardware in the presence of imperfect devices and control systems is a central challenge in realizing useful quantum computers. Susceptibility to noise in particular limits the performance and algorithmic capabilities experienced by end users. Fortunately, in both the NISQ era and beyond, quantum control enables the efficient execution of quantum logic operations and quantum algorithms exhibiting robustness to errors, without the need for complex logical encoding. We introduce the first commercial-grade software tools for quantum control in quantum computing research from Q-CTRL, serving the needs of hardware Rtextbackslash&D teams, algorithm developers, and end users. We survey quantum control and its role in combating noise in near-term devices; our primary focus is on quantum firmware, the low-level software solutions designed to enhance the stability of quantum computational hardware at the physical layer. We explain the benefits of quantum firmware not only in error suppression, but also in simplifying compilation protocols and enhancing the efficiency of quantum error correction. We provide an overview of Q-CTRL's software tools for creating and deploying quantum control solutions at various layers of the quantum computing software stack. We describe our software architecture leveraging both distributed cloud computation and local custom integration into hardware systems, and explain how key functionality is integrable with other quantum programming languages. We present a detailed technical overview of product features including a control-optimization engine, filter functions for general systems, and noise characterization. Finally, we present a series of case studies demonstrating the utility of quantum control solutions derived from these tools in improving the performance of trapped-ion and superconducting quantum computer hardware.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Manipulating quantum computing hardware in the presence of imperfect devices and control systems is a central challenge in realizing useful quantum computers. Susceptibility to noise in particular limits the performance and algorithmic capabilities experienced by end users. Fortunately, in both the NISQ era and beyond, quantum control enables the efficient execution of quantum logic operations and quantum algorithms exhibiting robustness to errors, without the need for complex logical encoding. We introduce the first commercial-grade software tools for quantum control in quantum computing research from Q-CTRL, serving the needs of hardware Rtextbackslash&D teams, algorithm developers, and end users. We survey quantum control and its role in combating noise in near-term devices; our primary focus is on quantum firmware, the low-level software solutions designed to enhance the stability of quantum computational hardware at the physical layer. We explain the benefits of quantum firmware not only in error suppression, but also in simplifying compilation protocols and enhancing the efficiency of quantum error correction. We provide an overview of Q-CTRL's software tools for creating and deploying quantum control solutions at various layers of the quantum computing software stack. We describe our software architecture leveraging both distributed cloud computation and local custom integration into hardware systems, and explain how key functionality is integrable with other quantum programming languages. We present a detailed technical overview of product features including a control-optimization engine, filter functions for general systems, and noise characterization. Finally, we present a series of case studies demonstrating the utility of quantum control solutions derived from these tools in improving the performance of trapped-ion and superconducting quantum computer hardware.
Tuckett, David K; Bartlett, Stephen D; Flammia, Steven T; Brown, Benjamin J
Fault-Tolerant Thresholds for the Surface Code in Excess of 5% under Biased Noise Journal Article
In: Physical Review Letters, vol. 124, no. 13, pp. 130501, 2020, ISSN: 0031-9007.
@article{Tuckett.2020,
title = {Fault-Tolerant Thresholds for the Surface Code in Excess of 5% under Biased Noise},
author = {David K Tuckett and Stephen D Bartlett and Steven T Flammia and Benjamin J Brown},
doi = {10.1103/physrevlett.124.130501},
issn = {0031-9007},
year = {2020},
date = {2020-01-01},
journal = {Physical Review Letters},
volume = {124},
number = {13},
pages = {130501},
abstract = {Noise in quantum computing is countered with quantum error correction. Achieving optimal performance will require tailoring codes and decoding algorithms to account for features of realistic noise, such as the common situation where the noise is biased towards dephasing. Here we introduce an efficient high-threshold decoder for a noise-tailored surface code based on minimum-weight perfect matching. The decoder exploits the symmetries of its syndrome under the action of biased noise and generalizes to the fault-tolerant regime where measurements are unreliable. Using this decoder, we obtain fault-tolerant thresholds in excess of 6% for a phenomenological noise model in the limit where dephasing dominates. These gains persist even for modest noise biases: we find a threshold of ∼5% in an experimentally relevant regime where dephasing errors occur at a rate 100 times greater than bit-flip errors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Noise in quantum computing is countered with quantum error correction. Achieving optimal performance will require tailoring codes and decoding algorithms to account for features of realistic noise, such as the common situation where the noise is biased towards dephasing. Here we introduce an efficient high-threshold decoder for a noise-tailored surface code based on minimum-weight perfect matching. The decoder exploits the symmetries of its syndrome under the action of biased noise and generalizes to the fault-tolerant regime where measurements are unreliable. Using this decoder, we obtain fault-tolerant thresholds in excess of 6% for a phenomenological noise model in the limit where dephasing dominates. These gains persist even for modest noise biases: we find a threshold of ∼5% in an experimentally relevant regime where dephasing errors occur at a rate 100 times greater than bit-flip errors.
Roberts, Sam; Bartlett, Stephen D
Symmetry-Protected Self-Correcting Quantum Memories Journal Article
In: Physical Review X, vol. 10, no. 3, pp. 031041, 2020.
@article{10.1103/physrevx.10.031041b,
title = {Symmetry-Protected Self-Correcting Quantum Memories},
author = {Sam Roberts and Stephen D Bartlett},
doi = {10.1103/physrevx.10.031041},
year = {2020},
date = {2020-01-01},
journal = {Physical Review X},
volume = {10},
number = {3},
pages = {031041},
abstract = {A self-correcting quantum memory can store and protect quantum information for a time that increases without bound with the system size and without the need for active error correction. We demonstrate that symmetry can lead to self-correction in 3D spin-lattice models. In particular, we investigate codes given by 2D symmetry-enriched topological (SET) phases that appear naturally on the boundary of 3D symmetry-protected topological (SPT) phases. We find that while conventional on-site symmetries are not sufficient to allow for self-correction in commuting Hamiltonian models of this form, a generalized type of symmetry known as a 1-form symmetry is enough to guarantee self-correction. We illustrate this fact with the 3D “cluster-state” model from the theory of quantum computing. This model is a self-correcting memory, where information is encoded in a 2D SET-ordered phase on the boundary that is protected by the thermally stable SPT ordering of the bulk. We also investigate the gauge color code in this context. Finally, noting that a 1-form symmetry is a very strong constraint, we argue that topologically ordered systems can possess emergent 1-form symmetries, i.e., models where the symmetry appears naturally, without needing to be enforced externally.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A self-correcting quantum memory can store and protect quantum information for a time that increases without bound with the system size and without the need for active error correction. We demonstrate that symmetry can lead to self-correction in 3D spin-lattice models. In particular, we investigate codes given by 2D symmetry-enriched topological (SET) phases that appear naturally on the boundary of 3D symmetry-protected topological (SPT) phases. We find that while conventional on-site symmetries are not sufficient to allow for self-correction in commuting Hamiltonian models of this form, a generalized type of symmetry known as a 1-form symmetry is enough to guarantee self-correction. We illustrate this fact with the 3D “cluster-state” model from the theory of quantum computing. This model is a self-correcting memory, where information is encoded in a 2D SET-ordered phase on the boundary that is protected by the thermally stable SPT ordering of the bulk. We also investigate the gauge color code in this context. Finally, noting that a 1-form symmetry is a very strong constraint, we argue that topologically ordered systems can possess emergent 1-form symmetries, i.e., models where the symmetry appears naturally, without needing to be enforced externally.
Grimsmo, Arne L; Combes, Joshua; Baragiola, Ben Q
Quantum computing with rotation-symmetric Bosonic codes Journal Article
In: Physical Review X, vol. 10, no. 1, pp. 011058, 2020.
@article{grimsmo2020quantum,
title = {Quantum computing with rotation-symmetric Bosonic codes},
author = {Arne L Grimsmo and Joshua Combes and Ben Q Baragiola},
year = {2020},
date = {2020-01-01},
journal = {Physical Review X},
volume = {10},
number = {1},
pages = {011058},
publisher = {APS},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Milne, Alistair R; Hempel, Cornelius; Li, Li; Edmunds, Claire L; Slatyer, Harry J; Ball, Harrison; Hush, Michael R; Biercuk, Michael J
Quantum oscillator noise spectroscopy via displaced Schrödinger cat states Journal Article
In: arXiv preprint arXiv:2010.04375, 2020.
BibTeX | Links:
@article{milne2020quantum,
title = {Quantum oscillator noise spectroscopy via displaced Schrödinger cat states},
author = {Alistair R Milne and Cornelius Hempel and Li Li and Claire L Edmunds and Harry J Slatyer and Harrison Ball and Michael R Hush and Michael J Biercuk},
url = {https://arxiv.org/abs/2010.04375},
year = {2020},
date = {2020-01-01},
journal = {arXiv preprint arXiv:2010.04375},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Smith, Thomas B; Cassidy, Maja C; Reilly, David J; Bartlett, Stephen D; Grimsmo, Arne L
Dispersive readout of Majorana qubits Journal Article
In: PRX Quantum, vol. 1, no. 2, pp. 020313, 2020.
@article{smith2020dispersive,
title = {Dispersive readout of Majorana qubits},
author = {Thomas B Smith and Maja C Cassidy and David J Reilly and Stephen D Bartlett and Arne L Grimsmo},
year = {2020},
date = {2020-01-01},
journal = {PRX Quantum},
volume = {1},
number = {2},
pages = {020313},
publisher = {APS},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Yang, Yuanyuan; Das, Kushal; Moini, Alireza; Reilly, David J
A cryo-CMOS voltage reference in 28-nm FDSOI Journal Article
In: IEEE Solid-State Circuits Letters, vol. 3, pp. 186–189, 2020.
@article{yang2020cryo,
title = {A cryo-CMOS voltage reference in 28-nm FDSOI},
author = {Yuanyuan Yang and Kushal Das and Alireza Moini and David J Reilly},
year = {2020},
date = {2020-01-01},
journal = {IEEE Solid-State Circuits Letters},
volume = {3},
pages = {186--189},
publisher = {IEEE},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pauka, SJ; Das, K; Hornibrook, JM; Gardner, GC; Manfra, MJ; Cassidy, MC; Reilly, DJ
Characterizing quantum devices at scale with custom cryo-CMOS Journal Article
In: Physical Review Applied, vol. 13, no. 5, pp. 054072, 2020.
@article{pauka2020characterizing,
title = {Characterizing quantum devices at scale with custom cryo-CMOS},
author = {SJ Pauka and K Das and JM Hornibrook and GC Gardner and MJ Manfra and MC Cassidy and DJ Reilly},
year = {2020},
date = {2020-01-01},
journal = {Physical Review Applied},
volume = {13},
number = {5},
pages = {054072},
publisher = {APS},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Jarratt, MC; Waddy, SJ; Jouan, A; Mahoney, AC; Gardner, GC; Fallahi, S; Manfra, MJ; Reilly, DJ
Detection of the Quantum Capacitance of a Point Contact via Dispersive Gate Sensing Journal Article
In: Physical Review Applied, vol. 14, no. 6, pp. 064021, 2020.
@article{jarratt2020detection,
title = {Detection of the Quantum Capacitance of a Point Contact via Dispersive Gate Sensing},
author = {MC Jarratt and SJ Waddy and A Jouan and AC Mahoney and GC Gardner and S Fallahi and MJ Manfra and DJ Reilly},
year = {2020},
date = {2020-01-01},
journal = {Physical Review Applied},
volume = {14},
number = {6},
pages = {064021},
publisher = {APS},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2019
Ball, H.; Marciniak, Ch. D.; Wolf, R. N.; Hung, A. T. -H.; Pyka, K.; Biercuk, M. J.
Site-resolved imaging of beryllium ion crystals in a high-optical-access Penning trap with inbore optomechanics Journal Article
In: Rev. Sci. Instrum., vol. 90, no. 5, pp. 053103, 2019.
BibTeX | Links:
@article{Ball2019,
title = {Site-resolved imaging of beryllium ion crystals in a high-optical-access Penning trap with inbore optomechanics},
author = {H. Ball and Ch. D. Marciniak and R. N. Wolf and A. T. -H. Hung and K. Pyka and M. J. Biercuk},
doi = {10.1063/1.5049506},
year = {2019},
date = {2019-05-01},
journal = {Rev. Sci. Instrum.},
volume = {90},
number = {5},
pages = {053103},
publisher = {AIP Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Yang, C H; Chan, K W; Harper, R; Huang, W; Evans, T; Hwang, J C C; Hensen, B; Laucht, A; Tanttu, T; Hudson, F E; Flammia, S T; Itoh, K M; Morello, A; Bartlett, S D; Dzurak, A S
Silicon qubit fidelities approaching incoherent noise limits via pulse engineering Journal Article
In: Nature Electronics, vol. 2, no. 4, pp. 151–158, 2019.
@article{Yang.2019,
title = {Silicon qubit fidelities approaching incoherent noise limits via pulse engineering},
author = {C H Yang and K W Chan and R Harper and W Huang and T Evans and J C C Hwang and B Hensen and A Laucht and T Tanttu and F E Hudson and S T Flammia and K M Itoh and A Morello and S D Bartlett and A S Dzurak},
url = {https://www.nature.com/articles/s41928-019-0234-1.epdf?shared_access_token=dwgc0pOWyz17aQfkQBd4wtRgN0jAjWel9jnR3ZoTv0O-UqCO5w04UHpr1iaXzevFLT0JVyPpg9mA3x2230uknqWY4orZ4AuvqFwyDcjiIUIlYS9H_CiaXwr7TrJtnh4_b0MJCLVSEYws_x-aTqCHRw%3D%3D},
doi = {10.1038/s41928-019-0234-1},
year = {2019},
date = {2019-01-01},
journal = {Nature Electronics},
volume = {2},
number = {4},
pages = {151--158},
abstract = {Spin qubits created from gate-defined silicon metal–oxide–semiconductor quantum dots are a promising architecture for quantum computation. The high single qubit fidelities possible in these systems, combined with quantum error correcting codes, could potentially offer a route to fault-tolerant quantum computing. To achieve fault tolerance, however, gate error rates must be reduced to below a certain threshold and, in general, correlated errors must be removed. Here we show that pulse engineering techniques can be used to reduce the average Clifford gate error rates for silicon quantum dot spin qubits down to 0.043%. This represents a factor of three improvement over state-of-the-art silicon quantum dot devices and extends the randomized benchmarking coherence time to 9.4 ms. By including tomographically complete measurements in our randomized benchmarking, we infer a higher-order feature of the noise called the unitarity, which measures the coherence of noise. This, in turn, allows us to theoretically predict that average gate error rates as low as 0.026% may be achievable with further pulse improvements. These spin qubit fidelities are ultimately limited by incoherent noise, which we attribute to charge noise from the silicon device structure or the environment. Pulse engineering techniques can be used to reduce the average Clifford gate error rates for silicon quantum dot spin qubits down to 0.043%, a factor of three improvement over state-of-the-art silicon devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Spin qubits created from gate-defined silicon metal–oxide–semiconductor quantum dots are a promising architecture for quantum computation. The high single qubit fidelities possible in these systems, combined with quantum error correcting codes, could potentially offer a route to fault-tolerant quantum computing. To achieve fault tolerance, however, gate error rates must be reduced to below a certain threshold and, in general, correlated errors must be removed. Here we show that pulse engineering techniques can be used to reduce the average Clifford gate error rates for silicon quantum dot spin qubits down to 0.043%. This represents a factor of three improvement over state-of-the-art silicon quantum dot devices and extends the randomized benchmarking coherence time to 9.4 ms. By including tomographically complete measurements in our randomized benchmarking, we infer a higher-order feature of the noise called the unitarity, which measures the coherence of noise. This, in turn, allows us to theoretically predict that average gate error rates as low as 0.026% may be achievable with further pulse improvements. These spin qubit fidelities are ultimately limited by incoherent noise, which we attribute to charge noise from the silicon device structure or the environment. Pulse engineering techniques can be used to reduce the average Clifford gate error rates for silicon quantum dot spin qubits down to 0.043%, a factor of three improvement over state-of-the-art silicon devices.
Tuckett, David K; Darmawan, Andrew S; Chubb, Christopher T; Bravyi, Sergey; Bartlett, Stephen D; Flammia, Steven T
Tailoring Surface Codes for Highly Biased Noise Journal Article
In: Physical Review X, vol. 9, no. 4, pp. 041031, 2019.
@article{Tuckett.2019,
title = {Tailoring Surface Codes for Highly Biased Noise},
author = {David K Tuckett and Andrew S Darmawan and Christopher T Chubb and Sergey Bravyi and Stephen D Bartlett and Steven T Flammia},
doi = {10.1103/physrevx.9.041031},
year = {2019},
date = {2019-01-01},
journal = {Physical Review X},
volume = {9},
number = {4},
pages = {041031},
abstract = {The surface code, with a simple modification, exhibits ultrahigh error-correction thresholds when the noise is biased toward dephasing. Here, we identify features of the surface code responsible for these ultrahigh thresholds. We provide strong evidence that the threshold error rate of the surface code tracks the hashing bound exactly for all biases and show how to exploit these features to achieve significant improvement in the logical failure rate. First, we consider the infinite bias limit, meaning pure dephasing. We prove that the error threshold of the modified surface code for pure dephasing noise is 50%, i.e., that all qubits are fully dephased, and this threshold can be achieved by a polynomial time-decoding algorithm. We demonstrate that the subthreshold behavior of the code depends critically on the precise shape and boundary conditions of the code. That is, for rectangular surface codes with standard rough or smooth open boundaries, it is controlled by the parameter g=gcd(j,k), where j and k are dimensions of the surface code lattice. We demonstrate a significant improvement in the logical failure rate with pure dephasing for coprime codes that have g=1 and closely related rotated codes, which have a modified boundary. The effect is dramatic: The same logical failure rate achievable with a square surface code and n physical qubits can be obtained with a coprime or rotated surface code using only O(n) physical qubits. Finally, we use approximate maximum-likelihood decoding to demonstrate that this improvement persists for a general Pauli noise biased toward dephasing. In particular, comparing with a square surface code, we observe a significant improvement in the logical failure rate against biased noise using a rotated surface code with approximately half the number of physical qubits.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The surface code, with a simple modification, exhibits ultrahigh error-correction thresholds when the noise is biased toward dephasing. Here, we identify features of the surface code responsible for these ultrahigh thresholds. We provide strong evidence that the threshold error rate of the surface code tracks the hashing bound exactly for all biases and show how to exploit these features to achieve significant improvement in the logical failure rate. First, we consider the infinite bias limit, meaning pure dephasing. We prove that the error threshold of the modified surface code for pure dephasing noise is 50%, i.e., that all qubits are fully dephased, and this threshold can be achieved by a polynomial time-decoding algorithm. We demonstrate that the subthreshold behavior of the code depends critically on the precise shape and boundary conditions of the code. That is, for rectangular surface codes with standard rough or smooth open boundaries, it is controlled by the parameter g=gcd(j,k), where j and k are dimensions of the surface code lattice. We demonstrate a significant improvement in the logical failure rate with pure dephasing for coprime codes that have g=1 and closely related rotated codes, which have a modified boundary. The effect is dramatic: The same logical failure rate achievable with a square surface code and n physical qubits can be obtained with a coprime or rotated surface code using only O(n) physical qubits. Finally, we use approximate maximum-likelihood decoding to demonstrate that this improvement persists for a general Pauli noise biased toward dephasing. In particular, comparing with a square surface code, we observe a significant improvement in the logical failure rate against biased noise using a rotated surface code with approximately half the number of physical qubits.