 |
Center for Nonlinear Studies |
Quantum experiments are performed in noisy platforms. In NISQ devices, realistic setups can be described by open systems or noisy Hamiltonians. Starting from a generic noisy Hamiltonian, I will first present a scheme to control the thermalization of a harmonic oscillator in arbitrary time [1].
Then, going beyond the noise-averaged density matrix, I will introduce the concept of stochastic operator variance (SOV) of an observable. The SOV [2] is an operator that characterizes the deviation of any operator from the noise-averaged operator in a stochastic evolution governed by the Hamiltonian. As such, it is relevant in the quantum simulation of open systems using NISQ devices, e.g., to engineer a given dissipative evolution. Surprisingly, we find that the evolution of the noise-averaged variance relates to an out-of-time-order correlator (OTOC), which connects fluctuations of the system with scrambling. This connection may allow computing the Lyapunov exponent and experimentally access OTOCs without the need to invert the sign of the Hamiltonian. I will illustrate the results in the stochastic LMG model, and show how noise changes the phase diagram of the system.
In a last part, I will focus on the dynamics generated by a stochastic non-Hermitian Hamiltonian. We introduce a new type of non-linear master equation. Looking at the stochastic dissipative qubit, we find that noise can used to control the dynamics, mainly to control the steady state and convergence time to it [3].
[1] L. Dupays, I. L. Egusquiza, A. del Campo, and A. Chenu. Superadiabatic thermalization of a quantum oscillator by engineered dephasing, Phys. Rev. Res. 2:033178 (2020)
[2] P. Martinez-Azcona, A.Kundu, A. del Campo, and A. Chenu, PRL 131:160202 (2023).
[3] P. Martinez-Azcona, A.Kundu, A. Saxena, A. del Campo, and A. Chenu, ArXiv:2407.07746 (2024).
Bio: Aurelia has been focusing on the study of quantum dynamics in open quantum systems, staring from photosynthetic light-harvesting antennae, and now looking a components of today's experimental platform. Since she moved to Uni Luxembourg in 2021, she build a group focusing on stochastic and non-Hermitian systems. This leads to new kind of dynamics, that we are exploring for engineering of quantum-related technologies. In addition, she has grown an interest for quantum chaos. Her result works introduced refined measure of quantum chaos, and detailed studies of the spectral statistics in non-Hermitian systems. This is relevant to study crossover from chaos to integrability, as well as transition from Hermitian to non-Hermitian.
Feel free to visit the CNLS visitor office to talk with her. https://chenulab.com
Join by phone +1-415-655-0002 US Toll
Access code: 2634 686 9659
Host PIN: 8236
Host: Akram Touil (T-4)