Multi-phonon relaxation and generation of quantum states in a nonlinear mechanical oscillator

TL;DR

This paper explores the quantum dynamics of anharmonic nano-mechanical oscillators, showing how multi-phonon processes can lead to non-classical steady states and proposing methods to verify these quantum features experimentally.

Contribution

It provides a theoretical analysis of multi-phonon relaxation processes and their role in generating and maintaining non-classical states in nano-mechanical systems.

Findings

Non-classical steady states can form due to two-phonon losses at zero temperature.

Thermal excitations and one-phonon losses cause relaxation of these states.

Signatures of quantum features are detectable in ring-down experiments.

Abstract

The dissipative quantum dynamics of an anharmonic oscillator is investigated theoretically in the context of carbon-based nano-mechanical systems. In the short-time limit, it is known that macroscopic superposition states appear for such oscillators. In the long-time limit, single and multi-phonon dissipation lead to decoherence of the non-classical states. However, at zero temperature, as a result of two-phonon losses the quantum oscillator eventually evolves into a non-classical steady state. The relaxation of this state due to thermal excitations and one-phonon losses is numerically and analytically studied. The possibility of verifying the occurrence of the non-classical state is investigated and signatures of the quantum features arising in a ring-down setup are presented. The feasibility of the verification scheme is discussed in the context of quantum nano-mechanical systems.