Recent Publications

Preparing Atomic Topological Quantum Matter by Adiabatic Nonunitary Dynamics

Citation:

S. Barbarino, J. Yu, P. Zoller, and J. C. Budich. 2020. “Preparing Atomic Topological Quantum Matter by Adiabatic Nonunitary Dynamics.” Physical Review Letters, 124.

Abstract:

Motivated by the outstanding challenge of realizing lowerature states of quantum matter in synthetic materials, we propose and study an experimentally feasible protocol for preparing topological states such as Chern insulators. By definition, such (nonsymmetry protected) topological phases cannot be attained without going through a phase transition in a closed system, largely preventing their preparation in coherent dynamics. To overcome this fundamental caveat, we propose to couple the target system to a conjugate system, so as to prepare a symmetry protected topological phase in an extended system by intermittently breaking the protecting symmetry. Finally, the decoupled conjugate system is discarded, thus projecting onto the desired topological state in the target system. By construction, this protocol may be immediately generalized to the class of invertible topological phases, characterized by the existence of an inverse topological order. We illustrate our findings with microscopic simulations on an experimentally realistic Chern insulator model of ultracold fermionic atoms in a driven spin-dependent hexagonal optical lattice.

Monitoring Quantum Simulators via Quantum Non-Demolition Couplings to Atomic Clock Qubits

Citation:

Denis V. Vasilyev, Andrey Grankin, Mikhail A. Baranov, Lukas M. Sieberer, and Peter Zoller. 2020. “Monitoring Quantum Simulators via Quantum Non-Demolition Couplings to Atomic Clock Qubits.” arXiv:2006.00214.

Abstract:

We discuss monitoring the time evolution of an analog quantum simulator via a quantum non-demolition (QND) coupling to an auxiliary `clock' qubit. The QND variable of interest is the `energy' of the quantum many-body system, represented by the Hamiltonian of the quantum simulator. We describe a physical implementation of the underlying QND Hamiltonian for Rydberg atoms trapped in tweezer arrays using laser dressing schemes for a broad class of spin models. As an application, we discuss a quantum protocol for measuring the spectral form factor of quantum many-body systems, where the aim is to identify signatures of ergodic vs. non-ergodic dynamics, which we illustrate for disordered 1D Heisenberg and Floquet spin models on Rydberg platforms. Our results also provide the physical ingredients for running quantum phase estimation protocols for measurement of energies, and preparation of energy eigenstates for a specified spectral resolution on an analog quantum simulator.
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