TY - JOUR

T1 - Topological protection and control of quantum Markovianity

AU - Lorenzo, Salvatore

AU - Giorgi, Gian Luca

AU - Longhi, Stefano

PY - 2020

Y1 - 2020

N2 - Under the Born-Markov approximation, a qubit system, such as a two-level atom, is known to undergo a memoryless decay of quantum coherence or excitation when weakly coupled to a featureless environment. Recently, it has been shown that unavoidable disorder in the environment is responsible for non-Markovian effects and information backflow from the environment into the system owing to Anderson localization. This turns disorder into a resource for enhancing non-Markovianity in the system-environment dynamics, which could be of relevance in cavity quantum electrodynamics. Here we consider the decoherence dynamics of a qubit weakly coupled to a two-dimensional bath with a nontrivial topological phase, such as a two-level atom embedded in a two-dimensional coupled-cavity array with a synthetic gauge field realizing a quantum-Hall bath, and show that Markovianity is protected against moderate disorder owing to the robustness of chiral edge modes in the quantum-Hall bath. Interestingly, switching off the gauge field, i.e., flipping the bath into a topological trivial phase, allows one to re-introduce non-Markovian effects. Such a result indicates that changing the topological phase of a bath by a tunable synthetic gauge field can be harnessed to control non-Markovian effects and quantum information backflow in a qubit-environment system. c 2020 by the authors. Licensee MDPI, Basel, Switzerland.

AB - Under the Born-Markov approximation, a qubit system, such as a two-level atom, is known to undergo a memoryless decay of quantum coherence or excitation when weakly coupled to a featureless environment. Recently, it has been shown that unavoidable disorder in the environment is responsible for non-Markovian effects and information backflow from the environment into the system owing to Anderson localization. This turns disorder into a resource for enhancing non-Markovianity in the system-environment dynamics, which could be of relevance in cavity quantum electrodynamics. Here we consider the decoherence dynamics of a qubit weakly coupled to a two-dimensional bath with a nontrivial topological phase, such as a two-level atom embedded in a two-dimensional coupled-cavity array with a synthetic gauge field realizing a quantum-Hall bath, and show that Markovianity is protected against moderate disorder owing to the robustness of chiral edge modes in the quantum-Hall bath. Interestingly, switching off the gauge field, i.e., flipping the bath into a topological trivial phase, allows one to re-introduce non-Markovian effects. Such a result indicates that changing the topological phase of a bath by a tunable synthetic gauge field can be harnessed to control non-Markovian effects and quantum information backflow in a qubit-environment system. c 2020 by the authors. Licensee MDPI, Basel, Switzerland.

KW - Anderson localization

KW - Decoherence dynamics

KW - Non-Markovianity in open quantum systems

KW - Quantum-Hall topological insulators

KW - Topological order

KW - Anderson localization

KW - Decoherence dynamics

KW - Non-Markovianity in open quantum systems

KW - Quantum-Hall topological insulators

KW - Topological order

UR - http://hdl.handle.net/10447/406242

M3 - Article

VL - 7

SP - 18-

JO - Photonics

JF - Photonics

SN - 2304-6732

ER -