A pair of interacting spins coupled to an environmental sea: dissipation and mutual decoherence

TL;DR

This paper investigates how two spins interacting via a common environment experience rapid decoherence, showing that environmental coupling significantly suppresses coherent quantum behavior even at weak interactions.

Contribution

It demonstrates that bath-mediated interactions cause strong decoherence in coupled spins, highlighting the impact on quantum measurement processes.

Findings

Decoherence is enhanced by bath-mediated coupling.

Coherent motion is destroyed unless interactions are extremely weak.

Mutual bias blocks coherent transitions between nearly degenerate states.

Abstract

We consider the quantum dynamics of two spin-1/2 systems, each coupled to a bath of oscillators, so that a bath-mediated coupling is generated between the spins. We find that the interactions destroys any coherent motion of the 2 spins, even if the coupling of each spin to the bath is quite weak, unless the interaction is extremely small. This is because the dynamic mutual bias between the spins blocks any coherent transitions between nearly degenerate states. In many quantum measurement operations this means that decoherence effects will be much stonger during the actual measurement