Abstract
Single-crystal diamond cavity optomechanical devices are a promising example of a hybrid quantum system: by coupling mechanical resonances to both light and electron spins, they can enable new ways for photons to control solid state qubits. However, realizing cavity optomechanical devices from high quality diamond chips has been an outstanding challenge. Here we demonstrate single-crystal diamond cavity optomechanical devices that can enable photon-phonon-spin coupling. Cavity optomechanical coupling to $2\,\text{GHz}$ frequency ($f_\text{m}$) mechanical resonances is observed. In room temperature ambient conditions, these resonances have a record combination of low dissipation (mechanical quality factor, $Q_\text{m} > 9000$) and high frequency, with $Q_\text{m}\cdot f_\text{m} \sim 1.9\times10^{13}$ sufficient for room temperature single phonon coherence. The system exhibits high optical quality factor ($Q_\text{o} > 10^4$) resonances at infrared and visible wavelengths, is nearly sideband resolved, and exhibits optomechanical cooperativity $C\sim 3$. The devices' potential for optomechanical control of diamond electron spins is demonstrated through radiation pressure excitation of mechanical self-oscillations whose 31 pm amplitude is predicted to provide 0.6 MHz coupling rates to diamond nitrogen vacancy center ground state transitions (6 Hz / phonon), and $\sim10^5$ stronger coupling rates to excited state transitions.
Highlights
Diamond cavity optomechanical devices are an attractive platform for controlling the interactions between light, vibrations, and electrons that underly future hybrid quantum technologies [1]
Cavity optomechanics [12] harness optical forces in place of piezoelectric actuation, allowing coherent phonon state manipulation [13,14,15] of GHz frequency mechanical resonators with quantum limited sensitivity [16]. These phonons can be made resonant with NV center electron spin transitions that are central to proposals for spin–spin entanglement [17], spin-phonon state transfer [18,19,20], spin-mediated mechanical normal mode cooling [17,21,22], and photon–phonon spin coupling [23]
We have shown that cavity optomechanical devices can be realized from single-crystal diamond, with record high ambient condition optomecanical cooperativity, C ∼ 3, and a Qm · f m product of 1.9 × 1013
Summary
Diamond cavity optomechanical devices are an attractive platform for controlling the interactions between light, vibrations, and electrons that underly future hybrid quantum technologies [1]. This allows for the realization of optomechanical cooperativity, C N g20∕γoγm ∼ 3, large enough (>1) for coherent photon–phonon coupling [13,14], where g0 ∼ 2π × 26 kHz is the single photon optomechanical coupling rate of the device and describes the expected shift in the cavity optical frequency due to the mechanical zero-point motion of the microdisk These devices operate on the border of the sidebandresolved regime (γo ∼ ωm), enabling radiation pressure backaction excitation of mechanical self-oscillations with ∼31 pm amplitude. The ability of the microdisks to support optical modes at visible wavelengths is compatible with resonant coupling to NV center optical transitions [29], as well as operation in fluid environments of interest for sensing applications [27]
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