Dissipation-induced first-order decoherence phase transition in a non-interacting fermionic system

TL;DR

This paper investigates a quantum phase transition in a dissipative fermionic chain, revealing a first-order decoherence transition driven by infinitesimal dissipation, with boundary effects resembling a second-order transition.

Contribution

It demonstrates that infinitesimal dissipation induces a first-order decoherence phase transition in a non-interacting fermionic system, analyzing boundary behaviors and disorder effects.

Findings

Infinitesimal dissipation causes a quantum phase transition.

Boundaries exhibit second-order transition characteristics.

Disorder effects are mitigated by environmental coupling.

Abstract

We consider a dissipative tight-binding chain. The dissipation manifests as tunneling into/out of the chain from/to a memoryless environment. The evolution of the system is described by the Lindblad equation. Already infinitesimally small dissipation along the chain induces a quantum phase transition (QPT). This is a decoherence QPT: the reduced density matrix of a subsystem (far from the ends of the chain) can be represented as the tensor product of single-site density matrices. We analyze the QPT in the thermodynamic limit by looking at the entropy and the response function in the bulk. We also explore the properties of the boundaries of the chain close to the transition point and observe that the boundaries behave as if they undergo a second-order phase transition with power-law divergence of the correlation functions and response function. Disorder is known to localize one-dimensional systems, but the coupling to the memoryless environment pushes the system back into the delocalized state even in the presence of disorder.