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

Design and experimental demonstration of optomechanical paddle nanocavities

We present the design, fabrication and initial characterization of a paddle nanocavity consisting of a suspended sub-picogram nanomechanical resonator optomechanically coupled to a photonic crystal nanocavity. The optical and mechanical properties of the paddle nanocavity can be systematically designed and optimized, and key characteristics including mechanical frequency easily tailored. Measurements under ambient conditions of a silicon paddle nanocavity demonstrate an optical mode with quality factor $Q_o$ ~ 6000 near 1550 nm, and optomechanical coupling to several mechanical resonances with frequencies $\omega_m/2\pi$ ~ 12-64 MHz, effective masses $m_\text{eff}$ ~ 350-650 fg, and mechanical quality factors $Q_m$ ~ 44-327. Paddle nanocavities are promising for optomechanical sensing and nonlinear optomechanics experiments.Comment: 5 pages, 4 figure

Single crystal diamond nanobeam waveguide optomechanics

Optomechanical devices sensitively transduce and actuate motion of nanomechanical structures using light. Single--crystal diamond promises to improve the performance of optomechanical devices, while also providing opportunities to interface nanomechanics with diamond color center spins and related quantum technologies. Here we demonstrate dissipative waveguide--optomechanical coupling exceeding 35 GHz/nm to diamond nanobeams supporting both optical waveguide modes and mechanical resonances, and use this optomechanical coupling to measure nanobeam displacement with a sensitivity of $9.5$ fm/$\sqrt{\text{Hz}}$ and optical bandwidth $>150$nm. The nanobeams are fabricated from bulk optical grade single--crystal diamond using a scalable undercut etching process, and support mechanical resonances with quality factor $2.5 \times 10^5$ at room temperature, and $7.2 \times 10^5$ in cryogenic conditions (5K). Mechanical self--oscillations, resulting from interplay between photothermal and optomechanical effects, are observed with amplitude exceeding 200 nm for sub-$\mu$W absorbed optical power, demonstrating the potential for optomechanical excitation and manipulation of diamond nanomechanical structures.Comment: Minor changes. Corrected error in units of applied stress in Fig. 1

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

Optomechanical Devices in Single Crystal Diamond

With recent advances in the field of optomechanics, researchers are always looking for new candidate materials with superior optical and mechanical characteristics. Diamond is a promising material due to its outstanding optical and mechanical properties, and holds great promise for a wide range of applications, in particular within the field of cavity optomechanics that couples optical and mechanical resonators. With a large transparency window that spans visible and infrared wavelengths, and a high optical refractive index, it allows light to be strongly confined in wavelength scale nanophotonic structures. Diamond has the highest thermal conductivity of any material at room temperature which allows thermal energy to be dissipated quickly when operating under high optical intensity. Owing to its high Young’s modulus, diamond is the hardest known material and diamond nanostructures support mechanical resonances with high frequencies compared to similar geometries in other materials. Moreover, diamond has been found to host more than a hundred colour centers, including the nitrogen vacancy (〖NV〗^-) and silicon vacancy (SiV) that hold a great promise for quantum information processing applications. The spin states of the 〖NV〗^- can be controlled both with photons and phonons, and fabricating optomechanical cavities in diamond makes it a viable platform for the realization of photon–phonon–spin interactions. Although these properties make diamond a great material for applications in cavity optomechanics and quantum information processing applications, fabrication of devices from bulk singlecrystal diamond (SCD) has proven to be challenging, as a sacrificial heterolayer does not exist for this material. While previous studies have shown that patterns with vertical profiles can be transferred to the SCD substrate using standard nanofabrication techniques, a major challenge in the fabrication of free standing optomechanical nanostructures is to etch away the layer underneath. Mechanical structures such as cantilevers and nanobeams require release from the substrate, enabling the study of mechanical vibrations. Similarly, optical cavities such as microdisk and photonic crystal cavities require undercut to prevent optical loss to the substrate. In this thesis, we demonstrate a new fabrication technique that utilizes oxygen plasma etching to fabricate optomechanical structures such as nanobeams and microdisks. The fabrication process is characterized, and found to demonstrate an undercut along diamond crystal planes. This technique uses standard nanofabrication equipment and can be extended to other bulk materials. The optical and mechanical characteristics of fabricated nanobeams and microdisks are analyzed using a dimpled fiber taper that evanescently couples light in and out of these devices. Nanobeams support mechanical modes with quality factors greater than 700,000 at cryogenic temperatures. Microdisks optomechanical cavities support whispering gallery optical modes with quality factors greater than 100,000 and room–temperature Q_m.f_m = 1.9×〖10〗^13, where Q_m and f_m are the mechanical quality factor and resonance frequencies of the microdisk mechanical breathing mode. Strong phonon–spin coupling is expected to be observed in future experiments by self–oscillating the mechanical devices, through photothermal or optical radiation pressure forces, providing a new scheme for phonon mediated optical control of 〖NV〗^- spin states

Manipulating NV centers with optomechanical crystals

Nanophotonic optomechanical devices allow efficient control of localized, high quality factor, nanoscale mechanical resonances. By optically actuating these resonances, the properties of embedded diamond nitrogen vacancy centers can be modulated with far off resonance photons. \ua9 2013 Optical Society of America.Peer reviewed: YesNRC publication: N

Efficient Fiber Collection of Nitrogen-Vacancy Center Emission from Diamond Nano Beams

We present tapered diamond nano beams, which allows efficient collection of diamond nitrogen vacancy emission through phase-matched coupling to a tapered optical fiber.Peer reviewed: YesNRC publication: Ye