@misc{10481/70386,
year = {2021},
month = {7},
url = {http://hdl.handle.net/10481/70386},
abstract = {Strong symmetries in open quantum systems lead to broken ergodicity and the emergence of
multiple degenerate steady states. From a quantum jump (trajectory) perspective, the appearance
of multiple steady states is related to underlying dynamical phase transitions (DPTs) at the
fluctuating level, leading to a dynamical coexistence of different transport channels classified by
symmetry. In this paper we investigate how strong symmetries affect both the transport properties
and the activity patterns of a particular class of Markovian open quantum system, a three-qubit
model under the action of a magnetic field and in contact with a thermal bath.We find a pair of
twin DPTs in exciton current statistics, induced by the strong symmetry and related by time
reversibility, where a zero-current exchange-antisymmetric phase coexists with a symmetric phase
of negative exciton current. On the other hand, the activity statistics exhibits a single DPT where
the symmetric and antisymmetric phases of different but nonzero activities dynamically coexists.
Interestingly, the maximum current and maximum activity phases do not coincide for this
three-qubits system. We also investigate how symmetries are reflected in the joint large deviation
statistics of the activity and the current, a central issue in the characterization of the complex
quantum jump dynamics. The presence of a strong symmetry under nonequilibrium conditions
implies non-analyticities in the dynamical free energy in the dual activity-current plane (or
equivalently in the joint activity-current large deviation function), including an activity-driven
current lockdown phase for activities below some critical threshold. Remarkably, the DPT
predicted around the steady state and its Gallavotti–Cohen twin dual are extended into lines of
first-order DPTs in the current-activity plane, with a nontrivial structure which depends on the
transport and activity properties of each of the symmetry phases. Finally, we also study the effect
of a symmetry-breaking, ergodicity-restoring dephasing channel on the coupled activity-current
statistics for this model. Interestingly, we observe that while this dephasing noise destroys the
symmetry-induced DPTs, the underlying topological symmetry leaves a dynamical fingerprint in
the form of an intermittent, bursty on/off dynamics between the different symmetry sectors.},
organization = {Spanish Ministry and Agencia Estatal de Investigacion (AEI)	FIS2017-84256-P},
organization = {Junta de Andalucia},
organization = {European Commission	A-FQM-175-UGR18	
SOMM17/6105/UGR},
publisher = {Institute of Physics Publishing},
keywords = {Fluctuations (Physics)},
keywords = {Spins},
keywords = {Large deviations},
keywords = {Non-equilibrium},
keywords = {Quantum open systems},
title = {Coupled activity-current fluctuations in open quantum systems under strong symmetries},
doi = {10.1088/1367-2630/ac0f19},
author = {Manzano Diosdado, Daniel and Martínez García, M. A. and Hurtado Fernández, Pablo Ignacio},
}