Dr. Ian Mondragon Shem, Northwestern University

Non-equilibrium phenomena in Rydberg atoms and circuit QED devices Progress in the design and coherent control of quantum simulators has enabled access to new fundamental discoveries in quantum many-body dynamics. The noisy nature of today’s devices, however, limits the possible simulations that can be carried out in practice. In this talk, I will present synergies between the discovery of new forms of non-equilibrium behavior in imperfect quantum simulators and the design of strategies to improve quantum hardware.

I will begin by focusing on the dynamics of strongly interacting Rydberg atoms. I will present evidence that most initial states lead to non-ergodic oscillations in local observables. This is due to a series of previously unknown quantum many-body scars in the energy spectrum. I will discuss how this non-ergodic behavior remains robust in the presence of disorder, suggesting potential applications in quantum metrology to diagnose spatial imperfections in Rydberg simulators.

I will afterward discuss strategies inspired by non-equilibrium phenomena to improve the performance of quantum hardware at the single-qubit level. Qubits in circuit QED systems can be strongly affected by 1/f noise, leading to strong dephasing. Based on models of time crystals, I will show how to create dynamical (Floquet) qubits that exhibit flat spectra with respect to external control parameters. This type of spectrum can result in dynamical qubits with a markedly reduced dephasing rate.

I will conclude by providing an outlook for the continued effort to understand non-equilibrium systems and how they can be used to improve quantum devices.