Qubit-induced phonon blockade as a signature of quantum behavior in nanomechanical resonators

TL;DR

This paper proposes using phonon blockade as a clear indicator of quantum behavior in nanomechanical resonators, achieved by coupling a superconducting qubit to induce nonlinear phonon interactions, and demonstrates its feasibility through simulations.

Contribution

It introduces a method to observe quantum behavior in nanomechanical resonators via phonon blockade induced by a superconducting qubit, supported by simulation results.

Findings

Phonon blockade can be observed with current experimental parameters.

Coupling a superconducting qubit induces the necessary nonlinearity.

Quantum oscillations are demonstrated in the nanomechanical resonator.

Abstract

The observation of quantized nanomechanical oscillations by detecting femtometer-scale displacements is a significant challenge for experimentalists. We propose that phonon blockade can serve as a signature of quantum behavior in nanomechanical resonators. In analogy to photon blockade and Coulomb blockade for electrons, the main idea for phonon blockade is that the second phonon cannot be excited when there is one phonon in the nonlinear oscillator. To realize phonon blockade, a superconducting quantum two-level system is coupled to the nanomechanical resonator and is used to induce the phonon self-interaction. Using Monte Carlo simulations, the dynamics of the induced nonlinear oscillator is studied via the Cahill-Glauber $s$-parametrized quasiprobability distributions. We show how the oscillation of the resonator can occur in the quantum regime and demonstrate how the phonon blockade can be observed with currently accessible experimental parameters.