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Generation of mechanical cat-like states via optomagnomechanics

Hao-Tian Li, Hong-Bin Wang, Zi-Xu Lu, Jie Li

TL;DR

This work addresses the challenge of creating macroscopic quantum superpositions in mechanical motion by leveraging an optomagnomechanical (OMM) platform. It proposes a two-step protocol: first, generate a squeezed mechanical state via a two-tone microwave drive on the magnon mode, then perform heralded phonon subtraction with a weak red-detuned optical pulse to produce a $k$-phonon-subtracted state, i.e., a cat-like mechanical state, conditioned on detecting $k$ anti-Stokes photons. The analysis shows that the steady-state mechanical mode becomes a two-mode Gaussian system under appropriate driving, with squeezing controlled by the ratio $G_+/G_-$ and temperature, and that phonon subtraction yields Wigner-function negativity characteristic of Schrödinger-cat-like states, with trade-offs between fidelity and success probability. The results open a pathway for macroscopic quantum state preparation in hybrid magnon-photon-phonon systems and have potential implications for quantum sensing and tests of collapse models, using experimentally realistic parameters.

Abstract

We propose an optomagnomechanical approach for preparing a cat-like superposition state of mechanical motion. Our protocol consists of two steps and is based on the magnomechanical system where the magnetostrictively induced displacement further couples to an optical cavity mode via radiation pressure. We first prepare a squeezed mechanical state by driving the magnomechanical system with a two-tone microwave field. We then switch off the microwave drives and send a weak red-detuned optical pulse to the optical cavity to weakly activate the optomechanical anti-Stokes scattering. We show that $k$ phonons can be subtracted from the prepared squeezed state, conditioned on the detection of $k$ anti-Stokes photons from the cavity output field, which prepares the mechanical motion in a cat-like state. The work provides a new avenue for preparing mechanical superposition states by combining opto- and magnomechanics and may find applications in the study of macroscopic quantum states and the test of collapse theories.

Generation of mechanical cat-like states via optomagnomechanics

TL;DR

This work addresses the challenge of creating macroscopic quantum superpositions in mechanical motion by leveraging an optomagnomechanical (OMM) platform. It proposes a two-step protocol: first, generate a squeezed mechanical state via a two-tone microwave drive on the magnon mode, then perform heralded phonon subtraction with a weak red-detuned optical pulse to produce a -phonon-subtracted state, i.e., a cat-like mechanical state, conditioned on detecting anti-Stokes photons. The analysis shows that the steady-state mechanical mode becomes a two-mode Gaussian system under appropriate driving, with squeezing controlled by the ratio and temperature, and that phonon subtraction yields Wigner-function negativity characteristic of Schrödinger-cat-like states, with trade-offs between fidelity and success probability. The results open a pathway for macroscopic quantum state preparation in hybrid magnon-photon-phonon systems and have potential implications for quantum sensing and tests of collapse models, using experimentally realistic parameters.

Abstract

We propose an optomagnomechanical approach for preparing a cat-like superposition state of mechanical motion. Our protocol consists of two steps and is based on the magnomechanical system where the magnetostrictively induced displacement further couples to an optical cavity mode via radiation pressure. We first prepare a squeezed mechanical state by driving the magnomechanical system with a two-tone microwave field. We then switch off the microwave drives and send a weak red-detuned optical pulse to the optical cavity to weakly activate the optomechanical anti-Stokes scattering. We show that phonons can be subtracted from the prepared squeezed state, conditioned on the detection of anti-Stokes photons from the cavity output field, which prepares the mechanical motion in a cat-like state. The work provides a new avenue for preparing mechanical superposition states by combining opto- and magnomechanics and may find applications in the study of macroscopic quantum states and the test of collapse theories.

Paper Structure

This paper contains 4 sections, 24 equations, 4 figures.

Table of Contents

  1. Introduction
  2. Magnomechanical SQUEEZING OF MECHANICAL motion
  3. PHONON SUBTRACTION via optical pulses
  4. Conclusions

Figures (4)

  • Figure 1: (a) Two-step protocol adopted to generate cat-like states of mechanical motion in an OMM system. First step: the magnon mode is driven by two microwave fields at the frequencies $\omega_\pm=\omega_m \pm \omega_b$ to prepare a mechanical squeezed state. Second step: a weak red-detuned optical pulse is sent to the optomechanical cavity to subtract phonons, conditioned on the detection of anti-Stokes photons in the cavity output field. (b) Frequencies of the magnomechanical subsystem and two microwave driving fields in the first step, and of the optomechanical subsystem and the weak optical pulse in the second step.
  • Figure 2: Wigner function of the squeezed mechanical mode. The dashed circle corresponds to vacuum fluctuation. The parameters are provided in the main text.
  • Figure 3: (a) Degree of squeezing $S$ (dB) of the mechanical mode versus $G_+/G_-$ for various temperatures. We fix the coupling $G_-/2\pi = 0.1$ MHz and vary $G_+$. (b) Degree of squeezing $S$ (dB) versus bath temperature $T$ and the coupling $G_-$. The coupling $G_+$ is optimized for each value of $G_-$, and the other parameters are as those in Fig. \ref{['fig2']}.
  • Figure 4: Wigner function of (a) the single-phonon [(b) the two-phonon] subtracted squeezed mechanical state. The parameters are provided in the text.