OpenQMBP2023: New perspectives in the out-of-equilibrium dynamics of open many-body quantum systems

Session

Quantum Trajectories and Measurement Induced Phase Transitions

Jun 20, 2023, 10:00 AM

Institut Pascal

7. Simulating quantum transport on classical computers: Bridging the high- and low-temperature limits

Curt von Keyserlingk (KCL)

6/20/23, 10:00 AM

Can we efficiently estimate transport coefficients (conductivities etc) in many-body quantum systems using classical computers? Drawing on lessons learned from studying scrambling and entanglement entropy dynamics in generic many-body systems, I propose an upper bound on the computational resources required to simulate transport at high temperatures: CPU time/memory $\sim...

8. Monte Carlo matrix-product-state approach to the false vacuum decay in the monitored quantum Ising chain

Alberto BIELLA (Pitaevskii BEC Center, CNR-INO and Università di Trento)

6/20/23, 10:25 AM

In this work we characterize the metastable dynamics in the ferromagnetic quantum Ising chain with a weak longitudinal field subject to continuous monitoring of the local magnetization. To this end we exploit a numerical approach based on the combination of matrix product states with stochastic quantum trajectories which allows for the simulation of the trajectory-resolved non-equilibrium...

72. Elusive phase transition in the replica limit of monitored systems

Guido Giachetti (CY Cergy Paris Université)

6/20/23, 10:50 AM

We study an exactly solvable model of monitored dynamics in a system of $N$ spin $1/2$ particles with pairwise all-to-all noisy interactions, where each spin is constantly perturbed by weak measurements of the spin component in a random direction. We make use of the replica trick to account for the Born's rule weighting of the measurement outcomes in the study of purification and other...

10. Topological transition in a continuously monitored free fermion model

Alessandro Romito (Lancaster University)

6/20/23, 11:25 AM

Local quantum measurements of many-body systems can induce phase transitions between volume and area law scaling of entanglement entropy.
Here we present a Gaussian fermionic model where continuous measurements of two non-commuting sets of observables induce a transition between area-law entanglement scaling phases of distinct topological order. We characterize the phase transition in terms...

11. TBA

Xhek Turkeshi (College de France)

6/20/23, 11:50 AM

16. Diffusion and subdiffusion in the disordered quantum and classical Heisenberg spin chains

Antonello Scardicchio

6/20/23, 2:00 PM

I will present some work on disordered Heisenberg model on a chain which shows that, depending on the strength of the disorder, both the classical and quantum model have a transition from diffusive to subdiffusive transport.
Based on:

AJ McRoberts, F Balducci, R Moessner, A Scardicchio
arXiv preprint arXiv:2304.05423

IV Protopopov, RK Panda, T Parolini, A Scardicchio, E Demler, DA...

14. Monitored Fermions: Phenomenology, Effective Theory and Dark State Phase Transitions

Michael Buchhold (University of Cologne)

6/20/23, 2:25 PM

Monitored Fermions provide a rich playground for the study of entanglement phase transitions in non-unitary quantum dynamics. We will discuss the phenomenology of entanglement transitions in several classes of monitored Hamiltonian systems and in fermion circuits and introduce effective theories describing both setups. We will then utilize adaptive feedback to reduce the configurational...

15. Triviality of quantum trajectories close to a directed percolation transition

Lorenzo Piroli (ENS Paris)

6/20/23, 3:00 PM

In this talk, I will discuss a variation of the standard framework of measurement-induced phase transitions, where the projective measurements are followed by control operations steering the system toward a pure absorbing state. In these dynamics, two types of phase transition occur as the rate of these control operations is increased: a measurement-induced entanglement transition, and a...

12. Entanglement dynamics with non-local measurements: Theoretical framework for Gaussian systems.

Giulia PICCITTO (Università degli studi di Pisa)

6/20/23, 3:25 PM

I will present the theory needed to apply a Gaussian-preserving operator to a fermionic Gaussian state. Then I will use this formalism to derive the equations of motions of a fermionic Kitaev chain following two different dynamic protocols, induced by the presence of the monitoring apparatus: a quantum-jump evolution with string operators and a quantum diffusion dynamics with long-range...

13. Entanglement dynamics with non-local measurements: Numerical results.

Davide ROSSINI (University of Pisa)

6/20/23, 3:50 PM

I will discuss some numerical results for the entanglement entropy dynamics
along the quantum trajectories of a fermionic Kitaev chain, in the presence of
measurements with a non-local character. The first part addresses a quantum-jump evolution with fixed-range string operators: a variety of behaviors emerge, ranging from volume-law, for extensive ranges of the string, to subvolume- and...