Non-Markovian thermal reservoirs for autonomous entanglement distribution

TL;DR

This paper introduces a scheme where non-Markovian thermal reservoirs enable steady-state entanglement between distant qubits, leveraging filtered thermal noise to enhance quantum communication.

Contribution

It demonstrates how non-Markovian thermal reservoirs can generate and sustain entanglement between separated qubits, a novel approach for quantum networks.

Findings

Entanglement arises when thermal source bandwidth is reduced.

A quasiadiabatic dark state explains the entanglement mechanism.

High temperatures eventually destroy the entangled state.

Abstract

We describe a novel scheme for the generation of stationary entanglement between two separated qubits that are driven by a purely thermal photon source. While in this scenario the qubits remain in a separable state at all times when the source is broadband, i.e. Markovian, the qubits relax into an entangled steady state once the bandwidth of the thermal source is sufficiently reduced. We explain this phenomenon by the appearance of a quasiadiabatic dark state and identify the most relevant nonadiabatic corrections that eventually lead to a breakdown of the entangled state, once the temperature is too high. This effect demonstrates how the non-Markovianity of an otherwise incoherent reservoir can be harnessed for quantum communication applications in optical, microwave, and phononic networks. As two specific examples, we discuss the use of filtered room-temperature noise as a passive resource for entangling distant superconducting qubits in a cryogenic quantum link or solid-state spin qubits in a phononic quantum channel.