Viewpoint in Physics Magazine22 April 2021
Dual-unitary gates on the cover of PRL12 March 2021
Our recent work on dual-unitary circuits has been published in Physical Review Letters! Check out the paper, titled "Ergodic and Nonergodic Dual-Unitary Quantum Circuits with Arbitrary Local Hilbert Space Dimension", here. Joint work with Austen Lamacraft.My lucky streak with APS continues — not only has this paper been selected as Editors' Suggestion, it also graces the cover of this week's issue of Physical Review Letters!
Dual-unitary quantum circuits can be used to construct 1+1 dimensional lattice models for which dynamical correlations of local observables can be explicitly calculated. We show how to analytically construct classes of dual-unitary circuits with any desired level of (non-)ergodicity for any dimension of the local Hilbert space, and present analytical results for thermalization to an infinite-temperature Gibbs state (ergodic) and a generalized Gibbs ensemble (nonergodic). It is shown how a tunable ergodicity-inducing perturbation can be added to a nonergodic circuit without breaking dual unitarity, leading to the appearance of prethermalization plateaux for local observables.
Shortcuts to dynamic polarization08 February 2021
Our paper on Shortcuts to dynamic polarization has now also been published in Physical Review B. Even better, it has been selected as Editors' Suggestion and is currently advertised on the Physical Review B homepage!
Dynamic polarization protocols aim to hyperpolarize a spin bath by transferring spin polarization from a well-controlled qubit such as a quantum dot or a color defect. Building on techniques from shortcuts to adiabaticity, we design fast and efficient dynamic polarization protocols in central spin models that apply to dipolarly interacting systems. The protocols maximize the transfer of polarization via bright states at a nearby integrable point, exploit the integrability-breaking terms to reduce the statistical weight on dark states that do not transfer polarization, and realize experimentally accessible local counterdiabatic driving through Floquet engineering. A master equation treatment suggests that the protocol duration scales linearly with the number of bath spins with a prefactor that can be orders of magnitude smaller than that of unassisted protocols. This work opens pathways to cool spin baths and extend qubit coherence times for applications in quantum information processing and metrology.