Abstract
Cavity optomechanics has achieved groundbreaking control and detection of mechanical oscillators, based on their coupling to linear electromagnetic modes. Recently, however, there is increasing interest in cavity nonlinearities as resource in radiation-pressure interacting systems. Here, we present a flux-mediated optomechanical device combining a nonlinear superconducting quantum interference cavity with a mechanical nanobeam. We demonstrate how the Kerr nonlinearity of the circuit can be used to enhance the device performance by suppressing cavity frequency noise, and for a counter-intuitive sideband-cooling scheme based on intracavity four-wave-mixing. With a large single-photon coupling rate of up to g0 = 2π ⋅ 3.6 kHz and a high mechanical quality factor Qm ≈ 4 ⋅ 105, we achieve an effective four-wave cooperativity of {{{{{{{{mathcal{C}}}}}}}}}_{{{{{{{{rm{fw}}}}}}}}}, > , 100 and demonstrate four-wave cooling of the mechanical oscillator close to its quantum groundstate. Our results advance the recently developed platform of flux-mediated optomechanics and demonstrate how cavity Kerr nonlinearities can be utilized in cavity optomechanics.
Highlights
Cavity optomechanics has achieved groundbreaking control and detection of mechanical oscillators, based on their coupling to linear electromagnetic modes
Our device combines a superconducting quantuminterference LC circuit with a mechanical nanobeam oscillator embedded into the loop of the superconducting quantum-interference device (SQUID), cf
At the core of the circuit, the SQUID acts as a magnetic-flux-dependent inductance LS(Φ), where Φ is the total magnetic flux threading the 21 × 3 μm[2] large loop
Summary
Cavity optomechanics has achieved groundbreaking control and detection of mechanical oscillators, based on their coupling to linear electromagnetic modes. Displacement detection with an imprecision below the standard quantum limit[2,3], sideband cooling to the motional quantum groundstate[4,5], the preparation of nonclassical states of motion[6,7,8,9], quantum entanglement of distinct mechanical oscillators[10,11], topological energy transfer using exceptional points[12], and microwave-to-optical-frequency transducers[13,14] are just some of the highlights that have been reported during the last decade All of these impressive results have been achieved with linear cavities, linear mechanical oscillators, and in the linearized regime of the optomechanical interaction utilizing largeamplitude cavity control fields, which limits the available possibilities for mechanical-state detection and control. The four-wave cooling scheme we implement here demonstrates how the cavity Kerr nonlinearity itself can be utilized for reducing cavity-frequency noise and for evading the Kerr cavity bifurcation instability in optomechanical sideband cooling
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