Quantum information and quantum computing
In quantum computation, a number of challenges need overcoming. Our group is actively engaged in developing new techniques for reduction of error rates in quantum gates and in the study of noise-robust states in topological superconductors and insulators.
Overview
Our work in this area is geared towards developing the building blocks and the protocols for quantum information processing with solid-state devices. Our research is strongly motivated by experiments, which routinely raise research questions in quantum optics and coherent control. The methodology involves taking a non-equilibrium open-system approach to modelling and employing large-scale computer simulations.
Research Team:
For relevant publications in this research area, please consult the websites of the research team members above.
Funding:
Quantum reservoir computing
Quantum reservoir computing is a promising paradigm in quantum machine learning that harnesses the inherent properties of quantum systems to enhance information processing.
This research explores the potential of quantum-inspired approaches, leveraging the rich dynamics of quantum reservoirs to solve complex computational tasks with improved efficiency and accuracy.
We are exploring the use of two-level atomic systems coupled to Lorentzian photonic cavities as a quantum computing reservoir system and are deploying its study both to standard machine-learning image-recognition problems and to the dynamics of open quantum systems. Our preliminary results suggest that the quantum physical reservoir computer is equally effective in generating valuable representations for quantum problems, even when faced with limited training data.
Scalability of optimal control in quantum computing
The race for scaling up quantum processors is ongoing, with one of the most challenging aspects being the need to reduce the error rate experienced when implementing quantum gates. These errors emanate from both random, uncontrollable external noise sources, as well as from limitations in precisely controlling a large array of qubits with limited ability to characterise and calibrate every element.
At Surrey, we are developing methods for improving quantum control to make it more robust to uncertainties while still maintaining scalability.
Topological states for quantum metrology and quantum computing
Topological superconductors and topological insulators possess ground states which are theorised to resist certain kinds of disorder and noise. Hence, they may be used as ideal quantum memories and have application in quantum metrology in defining electrical current.
We develop the theoretical framework and modelling required for the experimental proof-of-principle demonstration.
Superfluid quantum circuits for fundamental physics and quantum technology
The study of superfluid ³He has important particle-physics and cosmological implications. The normal phase of pure liquid ³He is separately invariant under spin and orbital rotations, gauge transformations, as well as discrete symmetries of space and time inversion. This rich symmetry structure has a close correspondence to the complex symmetry of the early universe.
It is believed that the early universe evolved after the Big Bang through a series of symmetry-breaking phase transitions, analogous to those in superfluid ³He. The Standard Model is an effective theory describing the low-energy phenomena that emerge from the cosmological vacuum.
In an analogous way, the effective theory describing the collective modes, quasiparticles and defects that emerge from the ground state of superfluid ³He offers a laboratory analogue of Standard-Model physics, due to the similarity of the maximal symmetry group with that of the early universe.
We propose superfluid ³He as a quantum simulator for Standard-Model physics in the laboratory. The low-pressure, low-temperature B-phase of this quantum liquid is a paradigm for time-reversal-invariant topological order. When ³He-B is confined on the mesoscopic scale (comparable to its coherence length), Andreev bound states with a Dirac-type spectrum are confined to the boundary of the superfluid. These are spin-polarised Majorana fermions created by Andreev processes at the boundary. Probing these states can shed light on hidden spinor degrees of freedom, testing the superselection rule in the Standard Model.
We have designed a device to probe this physics — a hybrid superconducting-superfluid device that could serve as an analogue of the superconducting quantum circuit. We aim to investigate the fundamental physics of qubit operation in this analogue system.