Single-crystal diamond low-dissipation cavity optomechanics

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.Comment: 12 pages, 5 figure

Fiber-taper collected emission from NV centers in high-Q/V diamond microdisks

Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume (V) of each cavity mode, the cavity quality factor (Q), and the coupling between the microdisk and the fiber. Here we observe room temperature photoluminescence from an ensemble of nitrogen-vacancy centers into high Q/V microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure Q ∼ 1 × 105 – the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of ∼50 are within reach

Single-crystal diamond low-dissipation cavity optomechanics

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 GHz frequency

Fiber-taper collected photoluminescence characterization of diamond microdisks

A key architectural element of future quantum photonic networks is an efficient light-matter interface to connect electronic and photonic qubit systems. Nanophotonic resonators can be fabricated on-chip to provide such interfaces for atomic-like defect centers in diamond, which are leading qubit candidates. Fabrication advancements have recently lead to the construction of high quality diamond microdisk resonators, which show potential to reach enhancements with Purcell factor CNV ∼ 50. Here, a room-temperature experimental apparatus integrating free space and visible wavelength fiber-taper measurement capabilities is built to characterize diamond microdisk resonators. Using this setup, microdisk wisphering gallery modes with quality factors at visible wavelengths resonant with defect centers as high as Q ∼ 1 × 105, are observed for the first time. Spectral filtering effects of the taper on the microdisk are analysed to reveal that coupling to these disks may be limited by phase matching requirements. By thinning these disks it should be possible to improve coupling while lowering mode volumes, as desired to optimize Purcell factors

Diamond microdisk cavity optomechanics

Optomechanical coupling between GHz frequency mechanical modes and λ ~ 1.5 µm optical modes in single–crystal diamond microdisks is demonstrated. The mechanical modes have a Q frequency product of 2 × 1013 Hz in ambient conditions, and are excited into ~ 31 pm self-oscillations by radiation pressure

High-Q diamond microdisks for coupling to SiV quantum emitters

We demonstrate diamond microdisk optical cavities with record quality factors (Q ~ 1 ×105) at 737 nm wavelengths near the optical transitions of implanted silicon vacancy (SiV) quantum emitters. Simulations indicate that Q/V > 1.2 ×104 is possible in these structures with optimized dimensions

Fiber-taper collected emission from NV centers in high-Q/VQ/V diamond microdisks

Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume ($V$) of each cavity mode, the cavity quality factor ($Q$), and the coupling between the microdisk and the fiber. Here we observe photoluminescence from an ensemble of nitrogen-vacancy centers into high $Q/V$ microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber-taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber-taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure $Q\sim 1\times10^{5}$ -- the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of $\sim 50$ are within reach

Supplement 1: Single-crystal diamond low-dissipation cavity optomechanics

Supplement 1 Originally published in Optica on 20 September 2016 (optica-3-9-963