Avoiding dissipation in a system of three quantum harmonic oscillators

TL;DR

This paper demonstrates how to engineer a three-oscillator quantum system to prevent dissipation in certain modes, enabling sustained quantum correlations and entanglement even at moderate temperatures, revealing complex dynamics beyond two-oscillator systems.

Contribution

It provides an analytical method to design couplings and frequencies for partial thermalization in three oscillators, enhancing control over decoherence and quantum correlations.

Findings

Partial thermalization enables asymptotic entanglement at moderate temperatures.

Hierarchical dissipation rates lead to long-lived quantum correlations.

Synchronous quadrature dynamics emerge during transient dissipation phases.

Abstract

We analyze the symmetries in an open quantum system composed by three coupled and detuned harmonic oscillators in the presence of a common heat bath. It is shown analytically how to engineer the couplings and frequencies of the system so as to have several degrees of freedom unaffected by decoherence, irrespective of the specific spectral density or initial state of the bath. This partial thermalization allows observing asymptotic entanglement at moderate temperatures, even in the nonresonant case. This latter feature cannot be seen in the simpler situation of only two oscillators, highlighting the richer structural variety of the three-body case. When departing from the strict conditions for partial thermalization, a hierarchical structure of dissipation rates for the normal modes is observed, leading to a long transient where quantum correlations such as the quantum discord are largely preserved, as well as to synchronous dynamics of the oscillators quadratures.