Two-Level System Nanomechanics in the Blue-Detuned Regime

TL;DR

This paper investigates a coupled two-level system and mechanical oscillator driven by blue-detuned light, revealing dynamical instabilities, non-classical states, and methods for their detection, with implications for quantum systems like superconducting qubits and NV centers.

Contribution

It introduces the study of two-level system nanomechanics in the blue-detuned regime, highlighting dynamical instabilities and non-classical state formation, and proposes detection techniques via photon emission spectra.

Findings

Dynamical instabilities lead to limit cycles in the oscillator.

Strong photon and phonon fluctuations characterized by large Fano factors.

Non-classical mechanical states emerge when coupling approaches mechanical frequency.

Abstract

We study a mechanical oscillator coupled to a two-level system driven by a blue-detuned coherent source in the resolved sideband regime. For weak mechanical damping, we find dynamical instabilities leading to limit cycles. They are signaled by strong fluctuations in the number of emitted photons, with a large Fano factor. The phonon-number fluctuations exhibit a strikingly similar behavior. When the coupling strength becomes comparable to the mechanical frequency, non-classical mechanical states appear. We demonstrate that these properties can be detected by measuring the photon-emission spectrum, which enables the reconstruction of the Wigner function. We then discuss the relation with cavity optomechanical systems. Candidates for observing these effects include superconducting qubits, NV centers, and single molecules coupled to oscillators.