Quantum Computing with Trapped Ions

Project Leader: Dr. Ting-Rei Tan

Quantum computing promises to totally transform information processing, making previously inaccessible problems of real societal and economic relevance solvable.

The Quantum Control Laboratory is leading the development of quantum computing hardware based on trapped ions. We’re focused primarily on the realisation of ultra-high fidelity, error-robust quantum logic, as well as techniques to characterise hardware performance.

Selected manuscripts:

• Phase-modulated entangling gates robust to static and time-varying errors
• Dynamically corrected gates suppress spatio-temporal error correlations as measured by randomized benchmarking
• Experimental quantum verification in the presence of temporally correlated noise
• Phase-modulated decoupling and error suppression in qubit-oscillator systems
• The effect of noise correlations on randomized benchmarking
• Long-time Low-latency Quantum Memory by Dynamical Decoupling

Quantum Simulation for Chemistry & Materials

Project Leader: Dr. Robert Wolf

The simulation of quantum coherent many-body systems is a promising new route to solve major problems in materials science for energy distribution. Through experiments using linear Paul traps and ion arrays in Penning traps we are seeking to engineer designer Hamiltonians for studies of problems including quantum magnetism and quantum chemistry.

Selected manuscripts:

• Site-resolved imaging of beryllium ion crystals in a high-optical-access Penning trap with inbore optomechanics
• Programmable quantum simulation by dynamic Hamiltonian engineering

Quantum Simulation of Chemical Dynamics

Project Leader: Dr. Ting-Rei Tan

In collaboration with Assoc. Prof. Ivan Kassal.

Simulating chemical dynamics is notoriously difficult on conventional computers, often scaling exponentially with molecular size.

We are developing new quantum technologies to enable simulations of a wide range of currently intractable chemistry problems. Our unique approach provides remarkable resource savings by leveraging under-used bosonic degrees of freedom in trapped-ion quantum computers to perform analog quantum simulations chemical dynamics.

Selected manuscripts:

• Direct Observation of geometric phase in dynamics around a conical intersection
• Predicting molecular vibronic spectra using time-domain analog quantum simulation
• Analog quantum simulation of chemical dynamics

Quantum Control Engineering

Project Leader: Dr. Ting-Rei Tan

Control theory is a universal enabling discipline within the engineering community. We are seeking to bring insights from control theory to the quantum domain, allowing us to efficiently exploit quantum coherent systems for applications in energy and computation. Our aim is to produce a flexible quantum control toolkit that is adaptable to any future quantum technology, but with specific emphasis on quantum computing. Projects relate to open-loop error suppression and the application of machine  learning to autonomous system tuneup and characterisation.

Selected manuscripts:

• Optimized Bayesian system identification in quantum devices
• Quantum oscillator noise spectroscopy via displaced Schrödinger cat states
• Integration of spectator qubits into quantum computer architectures for hardware tuneup and calibration
• Simultaneous spectral estimation of dephasing and amplitude noise on a qubit sensor via optimally band-limited control
• Autonomous adaptive noise characterization in quantum computers
• Machine learning for predictive estimation of qubit dynamics subject to dephasing
• Experimental noise filtering by quantum control

Hardware Systems for Quantum Technology & Precision Metrology

Project Leaders: Dr. Robert Wolf & Dr. Ting-Rei Tan

The realisation of quantum technology requires substantial investment in the development of advanced supporting technologies.  Our interests span from advanced laser systems to world-leading precision frequency references and their impacts on quantum system performance.

Selected manuscripts:

• The role of master clock stability in scalable quantum information processing
• Analytically exploiting noise correlations inside the feedback loop to improve locked-oscillator performance
• Prediction and real-time compensation of qubit decoherence via machine-learning
• Towards fully commercial, UV-compatible fiber patch cords
• High-power spectral beamsplitter for closely spaced frequencies
• Frequency Stabilization of a 369 nm Diode Laser by Nonlinear Spectroscopy of Ytterbium Ions in a Discharge