Showing 1–38 of 38 results for author: Barclay, P

Exceptional points in diamond optomechanics

Authors: Waleed El-Sayed, Elham Zohari, Joe Itoi, Peyman Parsa, Gustavo de Oliveira Luiz, Joseph E. Losby, Misa Hayashida, Marek Malac, Paul E. Barclay

Abstract: Multimode cavity optomechanical systems allow light to couple otherwise non-interacting mechanical resonators, enabling non-Hermitian phenomena such as exceptional points, where eigenfrequencies and eigenvectors of coupled modes coalesce. Accessing an exceptional point and its nearby parameter space is a first step towards chiral mode dynamics and topological state transfer. Diamond optomechanical… ▽ More Multimode cavity optomechanical systems allow light to couple otherwise non-interacting mechanical resonators, enabling non-Hermitian phenomena such as exceptional points, where eigenfrequencies and eigenvectors of coupled modes coalesce. Accessing an exceptional point and its nearby parameter space is a first step towards chiral mode dynamics and topological state transfer. Diamond optomechanical devices support strong coherent optomechanical coupling required to tune resonances to an exceptional point, as well as strain-coupling to spin-defects for hybrid quantum technologies, but have not yet been used for multimode non-Hermitian physics. Here we tune to an exceptional point in a diamond optomechanical crystal, which uses structural symmetry breaking to produce two high-frequency mechanical resonances coupled to an optical cavity. The exceptional point is reached within a stable operating window below the phonon-lasing threshold, and we observe asymmetric redistribution of optomechanical damping and anti-damping between hybridized modes. These results establish diamond optomechanical crystals as a platform for non-Hermitian optomechanics, opening routes to topological mechanical dynamics in hybrid spin-phonon interfaces. △ Less

Submitted 26 May, 2026; originally announced May 2026.

Comments: Main text: 7 pages, 4 figures. Supplementary information included

Optical Switching of $χ^{(2)}$ in Diamond Photonics

Authors: Sigurd Flågan, Joe Itoi, Prasoon K. Shandilya, Vinaya K. Kavatamane, Matthew Mitchell, David P. Lake, Paul E. Barclay

Abstract: Diamond's unique physical properties make it a versatile material for a wide range of nonlinear and quantum photonic technologies. However, unlocking diamond's full potential as a nonlinear photonic material with non-zero second-order susceptibility $χ^{(2)}\neq0$ requires symmetry breaking. In this work, we use a nanoscale cavity to demonstrate second-harmonic generation (SHG) in diamond, and dem… ▽ More Diamond's unique physical properties make it a versatile material for a wide range of nonlinear and quantum photonic technologies. However, unlocking diamond's full potential as a nonlinear photonic material with non-zero second-order susceptibility $χ^{(2)}\neq0$ requires symmetry breaking. In this work, we use a nanoscale cavity to demonstrate second-harmonic generation (SHG) in diamond, and demonstrate, for the first time, that the magnitude of the diamond's effective $χ^{(2)}$ strongly depends on the electronic configuration of defects in the diamond crystal, such as nitrogen-vacancy centres. The modification of $χ^{(2)}$ arises from photoionisation from the negative to neutral charge-state, and is manifested by quenching of SHG upon green illumination. Toggling the green illumination allows for optical switching of the device's $χ^{(2)}$. Optical control of $χ^{(2)}$ by defect engineering opens the door for second-order nonlinear processes in diamond. △ Less

Submitted 2 July, 2026; v1 submitted 21 November, 2024; originally announced December 2024.

Comments: 8 pages, 4 figures

Nonlinear optical charge state switching and pumping to a diamond NV center dark state

Authors: Prasoon K. Shandilya, Vinaya K. Kavatamane, Sigurd Flågan, David P. Lake, Denis Sukachev, Paul E. Barclay

Abstract: The photodynamics of diamond nitrogen-vacancy (NV) centers limits their performance in many quantum technologies. Quenching of photoluminescence, which degrades NV readout, is commonly ascribed to a dark state that is not fully understood. Using a nanoscale cavity to generate intense infrared fields that quench NV emission nonlinearly with field intensity, we show that the dark state is accessed b… ▽ More The photodynamics of diamond nitrogen-vacancy (NV) centers limits their performance in many quantum technologies. Quenching of photoluminescence, which degrades NV readout, is commonly ascribed to a dark state that is not fully understood. Using a nanoscale cavity to generate intense infrared fields that quench NV emission nonlinearly with field intensity, we show that the dark state is accessed by two-photon pumping into the $^4\!A_2$ quartet state of the neutrally charged NV (NV$^0$). We constrain this state's energy relative to the NV$^0$ ground-state ($^2\!E$) to ${<}0.58$\,eV and the recombination energy threshold to the NV$^-$ ground state ($^3\!A_2$) to $\leq2.33\,\text{eV}$. Furthermore, we estimate the intrinsic lifetime of $^4\!A_2$ state to be $1.78-6.06\,μ\text{s}$ and show that accessing this state allows sensing of local infrared fields. This new understanding will allow predictions of the limits of NV technologies reliant upon intense fields, including levitated systems, spin--optomechanical devices, and absorption--based magnetometers. △ Less

Submitted 2 July, 2026; v1 submitted 15 November, 2024; originally announced November 2024.

Comments: 23 pages, 11 figures

Determining Strain Components in a Diamond Waveguide from Zero-Field ODMR Spectra of NV$^{-}$ Center Ensembles

Authors: M. Sahnawaz Alam, Federico Gorrini, Michał Gawełczyk, Daniel Wigger, Giulio Coccia, Yanzhao Guo, Sajedeh Shahbazi, Vibhav Bharadwaj, Alexander Kubanek, Roberta Ramponi, Paul E. Barclay, Anthony J. Bennett, John P. Hadden, Angelo Bifone, Shane M. Eaton, Paweł Machnikowski

Abstract: The negatively charged nitrogen-vacancy (NV$^{-}$) center in diamond has shown great potential in nanoscale sensing and quantum information processing due to its rich spin physics. An efficient coupling with light, providing strong luminescence, is crucial for realizing these applications. Laser-written waveguides in diamond promote NV$^{-}$ creation and improve their coupling to light but, at the… ▽ More The negatively charged nitrogen-vacancy (NV$^{-}$) center in diamond has shown great potential in nanoscale sensing and quantum information processing due to its rich spin physics. An efficient coupling with light, providing strong luminescence, is crucial for realizing these applications. Laser-written waveguides in diamond promote NV$^{-}$ creation and improve their coupling to light but, at the same time, induce strain in the crystal. The induced strain contributes to light guiding but also affects the energy levels of NV$^{-}$ centers. We probe NV$^{-}$ spin states experimentally with the commonly used continuous-wave zero-field optically detected magnetic resonance (ODMR). In our waveguides, the ODMR spectra are shifted, split, and consistently asymmetric, which we attribute to the impact of local strain. To understand these features, we model ensemble ODMR signals in the presence of strain. By fitting the model results to the experimentally collected ODMR data, we determine the strain tensor components at different positions, thus determining the strain profile across the waveguide. This shows that zero-field ODMR spectroscopy can be used as a strain imaging tool. The resulting strain within the waveguide is dominated by a compressive axial component transverse to the waveguide structure, with a smaller contribution from vertical and shear strain components. △ Less

Submitted 12 August, 2024; v1 submitted 9 February, 2024; originally announced February 2024.

Comments: 12 pages, 7 figures + Supplementary Information (6 pages, 3 figures)

Einstein-de Haas torque as a discrete spectroscopic probe allows nanomechanical measurement of a magnetic resonance

Authors: K. R. Fast, J. E. Losby, G. Hajisalem, P. E. Barclay, M. R. Freeman

Abstract: The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of any temporal change of magnetism in an object. EdH torque results from conserving the object's total angular momentum: the angular momenta of all the specimen's magnetic moments, together with its mechanical angular momentum. Although the EdH effect is usually small and difficult to observe, it increases in magnitude wit… ▽ More The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of any temporal change of magnetism in an object. EdH torque results from conserving the object's total angular momentum: the angular momenta of all the specimen's magnetic moments, together with its mechanical angular momentum. Although the EdH effect is usually small and difficult to observe, it increases in magnitude with detection frequency. We explore the frequency-dependence of EdH torque for a thin film permalloy microstructure by employing a ladder of flexural beam modes (with five distinct resonance frequencies spanning from 3 to 208 MHz) within a nanocavity optomechanical torque sensor via magnetic hysteresis curves measured at mechanical resonances. At low DC fields the gyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz mechanical mode. The massive EdH mechanical torques arising from this co-resonance yield a fingerprint of vortex core pinning and depinning in the sample. The experimental results are discussed in relation to mechanical torques predicted from both macrospin (at high DC magnetic field) and finite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A global fit of the LLG solutions to the frequency-dependent data reveals a statistically significant discrepancy between the experimentally observed and simulated torque phase behaviours at spin texture transitions that can be reduced through the addition of a time constant to the conversion between magnetic cross-product torque and mechanical torque, constrained by experiment to be in the range of 0.5 - 4 ns. △ Less

Submitted 19 January, 2024; v1 submitted 27 October, 2023; originally announced October 2023.

Comments: 39 pages, 17 figures total (Main: 22 pages, 8 figures; Supplement: 17 pages, 9 figures)

High frequency torsional motion transduction using optomechanical coupled oscillators

Authors: Hamidreza Kaviani, Bishnupada Behera, Ghazal Hajisalem, Gustavo de Oliveira Luiz, David P. Lake, Paul E. Barclay

Abstract: Using light to measure an object's motion is central to operating mechanical sensors that probe forces and fields. Cavity optomechanical systems embed mechanical resonators inside optical resonators. This enhances the sensitivity of optomechanical measurements, but only if the mechanical resonator does not spoil the properties of the optical cavity. For example, cavity optomechanical detection of… ▽ More Using light to measure an object's motion is central to operating mechanical sensors that probe forces and fields. Cavity optomechanical systems embed mechanical resonators inside optical resonators. This enhances the sensitivity of optomechanical measurements, but only if the mechanical resonator does not spoil the properties of the optical cavity. For example, cavity optomechanical detection of resonators made from optically absorbing materials, or whose geometry does not possess suitable spatial symmetry, is challenging. Here we demonstrate a system that overcomes challenges in measuring high-frequency twisting motion of a nanodisk by converting them to vibrations of a photonic crystal cavity. Optomechanical readout of the cavity then enables measurement of the nanodisk's torsional resonances with sensitivity $5.1\times 10^{-21}-1.2\times 10^{-19}\,\text{Nm}/\sqrt{\text{Hz}}$ for a mechanical frequency range of 5--800 MHz. The nanodisk can be outfitted with magnetic nanostructures or metasurfaces without affecting the optical properties of the cavity, making the system suitable for torque magnetometry and structured light sensing. △ Less

Submitted 1 November, 2022; v1 submitted 15 August, 2022; originally announced August 2022.

Comments: 8 pages, 6 figures

Optomechanical Detection of Light with Orbital Angular Momentum

Authors: Hamidreza Kaviani, Roohollah Ghobadi, Bishnupada Behera, Marcelo Wu, Aaron Hryciw, Sonny Vo, David Fattal, Paul E. Barclay

Abstract: We present an optomechanical device designed to allow optical transduction of orbital angular momentum of light. An optically induced twist imparted on the device by light is detected using an integrated cavity optomechanical system based on a nanobeam slot-mode photonic crystal cavity. This device could allow measurement of the orbital angular momentum of light when photons are absorbed by the me… ▽ More We present an optomechanical device designed to allow optical transduction of orbital angular momentum of light. An optically induced twist imparted on the device by light is detected using an integrated cavity optomechanical system based on a nanobeam slot-mode photonic crystal cavity. This device could allow measurement of the orbital angular momentum of light when photons are absorbed by the mechanical element, or detection of the presence of photons when they are scattered into new orbital angular momentum states by a sub-wavelength grating patterned on the device. Such a system allows detection of a $l = 1$ orbital angular momentum field with an average power of $3.9\times10^3$ photons modulated at the mechanical resonance frequency of the device and can be extended to higher order orbital angular momentum states. △ Less

Submitted 18 December, 2019; originally announced December 2019.

Comments: 8 pages, 8 figures

Journal ref: Opt. Express 28, 15482-15496 (2020)

Two-axis cavity optomechanical torque characterization of magnetic microstructures

Authors: Ghazal Hajisalem, Joseph E. Losby, Gustavo de Oliveira Luiz, Vincent T. K. Sauer, Paul E. Barclay, Mark R. Freeman

Abstract: Significant new functionality is reported for torsion mechanical tools aimed at full magnetic characterizations of both spin statics and dynamics in micro- and nanostructures. Specifically, two orthogonal torque directions are monitored and the results co-analyzed to separate magnetic moment and magnetic susceptibility contributions to torque, as is desired for characterization of anisotropic thre… ▽ More Significant new functionality is reported for torsion mechanical tools aimed at full magnetic characterizations of both spin statics and dynamics in micro- and nanostructures. Specifically, two orthogonal torque directions are monitored and the results co-analyzed to separate magnetic moment and magnetic susceptibility contributions to torque, as is desired for characterization of anisotropic three-dimensional structures. The approach is demonstrated through application to shape and microstructural disorder-induced magnetic anisotropies in lithographically patterned permalloy, and will have utility for the determination of important magnetic thin-film and multilayer properties including interface anisotropy and exchange bias. The results reflect remarkable sensitivity of the out-of-plane magnetic torque to the nature of small edge domains perpendicular to the applied field direction, and also contain tantalizing indications of direct coupling to spin dynamics at the frequency of the mechanics. △ Less

Submitted 4 September, 2019; originally announced September 2019.

Journal ref: G Hajisalem et al 2019 New J. Phys. 21 095005

Influence of nanostructuring on silicon vacancy center spins in diamond pillars

Authors: Thomas Lutz, Tamiko Masuda, John P. Hadden, Ilja Fescenko, Victor Acosta, Wolfgang Tittel, Paul E. Barclay

Abstract: Color centers in diamond micro and nano structures are under investigation for a plethora of applications. However, obtaining high quality color centers in small structures is challenging, and little is known about how properties such as spin population lifetimes change during the transition from bulk to micro and nano structures. In this manuscript, we studied various ways to prepare diamond samp… ▽ More Color centers in diamond micro and nano structures are under investigation for a plethora of applications. However, obtaining high quality color centers in small structures is challenging, and little is known about how properties such as spin population lifetimes change during the transition from bulk to micro and nano structures. In this manuscript, we studied various ways to prepare diamond samples containing silicon vacancy centers and measured how population lifetimes of orbital states change in pillars as we varied their dimensions from approximately 1 $μ$m to 120 nm. We also researched the influence of the properties of the diamond substrate and the implantation and annealing methods on the silicon vacancy inhomogeneous linewidth and orbital lifetime. Our measurements show that nominally identical diamond samples can display significantly distinct inhomogeneous broadening. We observed weak indications that restricted vibrational modes in small structures may extend population lifetimes. However, imperfections in the crystal lattice or surface damage caused by etching reduce population lifetimes, especially in the smallest structures. △ Less

Submitted 5 August, 2019; originally announced August 2019.

Comments: 5 pages, 5 figures

Tunable amplification and cooling of a diamond resonator with a microscope

Authors: Harishankar Jayakumar, Behzad Khanaliloo, David P. Lake, Paul E. Barclay

Abstract: Controlling the dynamics of mechanical resonators is central to many quantum science and metrology applications. Optomechanical control of diamond resonators is attractive owing to diamond's excellent physical properties and its ability to host electronic spins that can be coherently coupled to mechanical motion. Using a confocal microscope, we demonstrate tunable amplification and damping of a di… ▽ More Controlling the dynamics of mechanical resonators is central to many quantum science and metrology applications. Optomechanical control of diamond resonators is attractive owing to diamond's excellent physical properties and its ability to host electronic spins that can be coherently coupled to mechanical motion. Using a confocal microscope, we demonstrate tunable amplification and damping of a diamond nanomechanical resonator's motion. Observation of both normal mode cooling from room temperature to 80K, and amplification into self--oscillations with $60\,μ\text{W}$ of optical power is observed via waveguide optomechanical readout. This system is promising for quantum spin-optomechanics, as it is predicted to enable optical control of stress-spin coupling with rates of $\sim$ 1 MHz (100 THz) to ground (excited) states of diamond nitrogen vacancy centers. △ Less

Submitted 10 March, 2021; v1 submitted 9 October, 2018; originally announced October 2018.

Journal ref: Phys. Rev. Applied 16, 014063 (2021)

Hexagonal boron nitride cavity optomechanics

Authors: Prasoon K. Shandilya, Johannes E. Fröch, Matthew Mitchell, David P. Lake, Sejeong Kim, Milos Toth, Bishnupada Behera, Chris Healey, Igor Aharonovich, Paul E. Barclay

Abstract: Hexagonal boron nitride (hBN) is an emerging layered material that plays a key role in a variety of two-dimensional devices, and has potential applications in nanophotonics and nanomechanics. Here, we demonstrate the first cavity optomechanical system incorporating hBN. Nanomechanical resonators consisting of hBN beams with predicted thickness between 8 nm and 51 nm were fabricated using electron… ▽ More Hexagonal boron nitride (hBN) is an emerging layered material that plays a key role in a variety of two-dimensional devices, and has potential applications in nanophotonics and nanomechanics. Here, we demonstrate the first cavity optomechanical system incorporating hBN. Nanomechanical resonators consisting of hBN beams with predicted thickness between 8 nm and 51 nm were fabricated using electron beam induced etching and positioned in the optical nearfield of silicon microdisk cavities. A 160 fm/$\sqrt{\text{Hz}}$ sensitivity to the hBN nanobeam motion is demonstrated, allowing observation of thermally driven mechanical resonances with frequencies between 1 and 23 MHz, and mechanical quality factors reaching 1100 at room temperature in high vacuum. In addition, the role of air damping is studied via pressure dependent measurements. Our results constitute an important step towards realizing integrated optomechanical circuits employing hBN. △ Less

Submitted 16 December, 2018; v1 submitted 11 September, 2018; originally announced September 2018.

Comments: Revised version

Realizing $Q$ > 300,000 in diamond microdisks for optomechanics via etch optimization

Authors: Matthew Mitchell, David P. Lake, Paul E. Barclay

Abstract: Nanophotonic structures in single--crystal diamond (SCD) that simultaneously confine and co-localize photons and phonons are highly desirable for applications in quantum information science and optomechanics. Here we describe an optimized process for etching SCD microdisk structures designed for optomechanics applications. This process allows the optical quality factor, $Q$, of these devices to be… ▽ More Nanophotonic structures in single--crystal diamond (SCD) that simultaneously confine and co-localize photons and phonons are highly desirable for applications in quantum information science and optomechanics. Here we describe an optimized process for etching SCD microdisk structures designed for optomechanics applications. This process allows the optical quality factor, $Q$, of these devices to be enhanced by a factor of 4 over previous demonstrations to $Q \sim 335,000$, which is sufficient to enable sideband resolved coherent cavity optomechanical experiments. Through analysis of optical loss and backscattering rates we find that $Q$ remains limited by surface imperfections. We also describe a technique for altering microdisk pedestal geometry which could enable reductions in mechanical dissipation. △ Less

Submitted 12 February, 2019; v1 submitted 23 August, 2018; originally announced August 2018.

Comments: Published version

Journal ref: APL Photonics 4, 016101 (2019)

Optomechanically induced transparency and cooling in thermally stable diamond microcavities

Authors: David P. Lake, Matthew Mitchell, Yasmeen Kamaliddin, Paul E. Barclay

Abstract: Diamond cavity optomechanical devices hold great promise for quantum technology based on coherent coupling between photons, phonons and spins. These devices benefit from the exceptional physical properties of diamond, including its low mechanical dissipation and optical absorption. However the nanoscale dimensions and mechanical isolation of these devices can make them susceptible to thermo-optic… ▽ More Diamond cavity optomechanical devices hold great promise for quantum technology based on coherent coupling between photons, phonons and spins. These devices benefit from the exceptional physical properties of diamond, including its low mechanical dissipation and optical absorption. However the nanoscale dimensions and mechanical isolation of these devices can make them susceptible to thermo-optic instability when operating at the high intracavity field strengths needed to realize coherent photon--phonon coupling. In this work, we overcome these effects through engineering of the device geometry, enabling operation with large photon numbers in a previously thermally unstable regime of red-detuning. We demonstrate optomechanically induced transparency with cooperativity > 1 and normal mode cooling from 300 K to 60 K, and predict that these device will enable coherent optomechanical manipulation of diamond spin systems. △ Less

Submitted 4 December, 2017; originally announced December 2017.

Modification of relaxation dynamics in Tb$^{3+}$:Y$_3$Al$_5$O$_{12}$ nanopowders

Authors: Thomas Lutz, Lucile Veissier, Philip J. T. Woodburn, Rufus L. Cone, Paul E. Barclay, Wolfgang Tittel, Charles W. Thiel

Abstract: Nanostructured rare-earth-ion doped materials are increasingly being investigated for on-chip implementations of quantum information processing protocols as well as commercial applications such as fluorescent lighting. However, achieving high-quality and optimized materials at the nanoscale is still challenging. Here we present a detailed study of the restriction of phonon processes in the transit… ▽ More Nanostructured rare-earth-ion doped materials are increasingly being investigated for on-chip implementations of quantum information processing protocols as well as commercial applications such as fluorescent lighting. However, achieving high-quality and optimized materials at the nanoscale is still challenging. Here we present a detailed study of the restriction of phonon processes in the transition from bulk crystals to small ($\le$ 40 nm) nanocrystals by observing the relaxation dynamics between crystal-field levels of Tb$^{3+}$:Y$_3$Al$_5$O$_{12}$. We find that population relaxation dynamics are modified as the particle size is reduced, consistent with our simulations of inhibited relaxation through a modified vibrational density of states and hence modified phonon emission. However, our experiments also indicate that non-radiative processes not driven by phonons are also present in the smaller particles, causing transitions and rapid thermalization between the levels on a timescale of $<$100 ns. △ Less

Submitted 1 March, 2018; v1 submitted 6 November, 2017; originally announced November 2017.

Comments: 9 pages, 9 figures

Journal ref: Phys. Rev. B 98, 054308 (2018)

Towards a Room-Temperature Spin-Photon Interface based on Nitrogen-Vacancy centers and Optomechanics

Authors: Roohollah Ghobadi, Stephen Wein, Hamidreza Kaviani, Paul Barclay, Christoph Simon

Abstract: The implementation of quantum networks involving quantum memories and photonic channels without the need for cryogenics would be a major technological breakthrough. Nitrogen-vacancy centers have excellent spin properties even at room temperature, but phonon-induced broadening makes it challenging to interface these spins with photons at non-cryogenic temperatures. Inspired by recent progress in ac… ▽ More The implementation of quantum networks involving quantum memories and photonic channels without the need for cryogenics would be a major technological breakthrough. Nitrogen-vacancy centers have excellent spin properties even at room temperature, but phonon-induced broadening makes it challenging to interface these spins with photons at non-cryogenic temperatures. Inspired by recent progress in achieving ultra-high mechanical quality factors, we propose that this challenge can be overcome by spin-opto-mechanical transduction. We quantify the coherence of the interface by calculating the indistinguishability of the emitted photons and describe promising paths towards experimental implementation. △ Less

Submitted 3 February, 2019; v1 submitted 6 November, 2017; originally announced November 2017.

Comments: 5 pages, 2 figures

Journal ref: Phys. Rev. A 99, 053825 (2019)

Effects of mechanical processing and annealing on optical coherence properties of Er$^{3+}$:LiNbO$_3$ powders

Authors: Thomas Lutz, Lucile Veissier, Charles W. Thiel, Philip J. T. Woodburn, Rufus L. Cone, Paul E. Barclay, Wolfgang Tittel

Abstract: Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er$^{3+}$:LiNbO$_3$) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are used to assess the coherence lifetimes for these highly scattering media. Direct intensity or heterodyne detection of two-pulse photon echo techniq… ▽ More Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er$^{3+}$:LiNbO$_3$) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are used to assess the coherence lifetimes for these highly scattering media. Direct intensity or heterodyne detection of two-pulse photon echo techniques was employed for samples with longer coherence lifetimes and larger signal strengths, while time-delayed optical free induction decays were found to work well for shorter coherence lifetimes and weaker signal strengths. Spectral hole burning techniques were also used to characterize samples with very rapid dephasing processes. The results on powders are compared to the properties of a bulk crystal, with observed differences explained by the random orientation of the particles in the powders combined with new decoherence mechanisms introduced by the powder fabrication. Modeling of the coherence decay shows that paramagnetic materials such as Er$^{3+}$:LiNbO$_3$ that have highly anisotropic interactions with an applied magnetic field can still exhibit long coherence lifetimes and relatively simple decay shapes even for a powder of randomly oriented particles. We find that coherence properties degrade rapidly from mechanical treatment when grinding powders from bulk samples, leading to the appearance of amorphous-like behavior and a broadening of up to three orders of magnitude for the homogeneous linewidth even when low-energy grinding methods are employed. Annealing at high temperatures can improve the properties in some samples, with homogeneous linewidths reduced to less than 10 kHz, approaching the bulk crystal linewidth of 3 kHz under the same experimental conditions. △ Less

Submitted 20 January, 2017; originally announced January 2017.

Comments: 13 pages, 7 figures

Journal ref: Journal of Luminescence 191PA (2017) pp. 2-12

Integrated waveguides and deterministically positioned nitrogen vacancy centers in diamond created by femtosecond laser writing

Authors: J. P. Hadden, V. Bharadwaj, B. Sotillo, S. Rampini, R. Osellame, J. Witmer, H. Jayakumar, T. T. Fernandez, A. Chiappini, C. Armellini, M. Ferrari, R. Ramponi, P. E. Barclay, S. M. Eaton

Abstract: Diamond's nitrogen vacancy (NV) center is an optically active defect with long spin coherence times, showing great potential for both efficient nanoscale magnetometry and quantum information processing schemes. Recently, both the formation of buried 3D optical waveguides and high quality single NVs in diamond were demonstrated using the versatile femtosecond laser-writing technique. However, until… ▽ More Diamond's nitrogen vacancy (NV) center is an optically active defect with long spin coherence times, showing great potential for both efficient nanoscale magnetometry and quantum information processing schemes. Recently, both the formation of buried 3D optical waveguides and high quality single NVs in diamond were demonstrated using the versatile femtosecond laser-writing technique. However, until now, combining these technologies has been an outstanding challenge. In this work, we fabricate laser written photonic waveguides in quantum grade diamond which are aligned to within micron resolution to single laser-written NVs, enabling an integrated platform providing deterministically positioned waveguide-coupled NVs. This fabrication technology opens the way towards on-chip optical routing of single photons between NVs and optically integrated spin-based sensing. △ Less

Submitted 12 March, 2018; v1 submitted 20 January, 2017; originally announced January 2017.

Journal ref: Optics Letters 43(15):pp. 3586-3589 (2018)

An upper limit on the lateral vacancy diffusion length in diamond

Authors: J. O. Orwa, K. Ganesan, J. Newnham, C. Santori, P. Barclay, K. M. C. Fu, R. G. Beausoleil, I. Aharonovich, B. A. Fairchild, P. Olivero, A. D. Greentree, S. Prawer

Abstract: Ion implantation is widely used to modify the structural, electrical and optical properties of materials. By appropriate masking, this technique can be used to define nano- and micro-structures. However, depending on the type of mask used, experiments have shown that vacancy-related substrate modification can be inferred tens of microns away from the edge of the mask used to define the implanted r… ▽ More Ion implantation is widely used to modify the structural, electrical and optical properties of materials. By appropriate masking, this technique can be used to define nano- and micro-structures. However, depending on the type of mask used, experiments have shown that vacancy-related substrate modification can be inferred tens of microns away from the edge of the mask used to define the implanted region. This could be due to fast diffusion of vacancies from the implanted area during annealing or to a geometric effect related to ion scattering around the mask edges. For quantum and single-atom devices, stray ion damage can be deleterious and must be minimized. In order to profile the distribution of implantation-induced damage, we have used the nitrogen-vacancy colour centre as a sensitive marker for vacancy concentration and distribution following MeV He ion implantation into diamond and annealing. Results show that helium atoms implanted through a mask clamped to the diamond surface are scattered underneath the mask to distances in the range of tens of micrometers from the mask edge. Implantation through a lithographically defined and deposited mask, with no spacing between the mask and the substrate, significantly reduces the scattering to <5 m but does not eliminate it. These scattering distances are much larger than the theoretically estimated vacancy diffusion distance of 260 nm under similar conditions. This paper shows that diffusion, upon annealing, of vacancies created by ion implantation in diamond is limited and the appearance of vacancies many tens of micrometers from the edge of the mask is due to scattering effects. △ Less

Submitted 25 August, 2016; originally announced August 2016.

Comments: 21 pages, 4 figures

Journal ref: Diamond and Related Materials 24, 6-10 (2012)

Quadratic Zeeman effect and spin-lattice relaxation of Tm$^{3+}$:YAG at high magnetic fields

Authors: Lucile Veissier, Charles W. Thiel, Thomas Lutz, Paul E. Barclay, Wolfgang Tittel, Rufus L. Cone

Abstract: Anisotropy of the quadratic Zeeman effect for the $^3{\rm H}_6 \rightarrow \, ^3{\rm H}_4$ transition at 793 nm wavelength in $^{169}$Tm$^{3+}$-doped Y$_3$Al$_5$O$_{12}$ is studied, revealing shifts ranging from near zero up to + 4.69 GHz/T$^2$ for ions in magnetically inequivalent sites. This large range of shifts is used to spectrally resolve different subsets of ions and study nuclear spin rela… ▽ More Anisotropy of the quadratic Zeeman effect for the $^3{\rm H}_6 \rightarrow \, ^3{\rm H}_4$ transition at 793 nm wavelength in $^{169}$Tm$^{3+}$-doped Y$_3$Al$_5$O$_{12}$ is studied, revealing shifts ranging from near zero up to + 4.69 GHz/T$^2$ for ions in magnetically inequivalent sites. This large range of shifts is used to spectrally resolve different subsets of ions and study nuclear spin relaxation as a function of temperature, magnetic field strength, and orientation in a site-selective manner. A rapid decrease in spin lifetime is found at large magnetic fields, revealing the weak contribution of direct-phonon absorption and emission to the nuclear spin-lattice relaxation rate. We furthermore confirm theoretical predictions for the phonon coupling strength, finding much smaller values than those estimated in the limited number of past studies of thulium in similar crystals. Finally, we observe a significant -- and unexpected -- magnetic field dependence of the two-phonon Orbach spin relaxation process at higher field strengths, which we explain through changes in the electronic energy-level splitting arising from the quadratic Zeeman effect. △ Less

Submitted 22 August, 2016; originally announced August 2016.

Comments: 10 pages, 9 figures

Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry

Authors: Marcelo Wu, Nathanael L. -Y. Wu, Tayyaba Firdous, Fatemeh Fani Sani, Joseph E. Losby, Mark R. Freeman, Paul E. Barclay

Abstract: Nanophotonic optomechanical devices allow observation of nanoscale vibrations with sensitivity that has dramatically advanced metrology of nanomechanical structures [1-9] and has the potential to impact studies of nanoscale physical systems in a similar manner [10, 11]. Here we demonstrate this potential with a nanophotonic optomechanical torque magnetometer and radiofrequency (RF) magnetic suscep… ▽ More Nanophotonic optomechanical devices allow observation of nanoscale vibrations with sensitivity that has dramatically advanced metrology of nanomechanical structures [1-9] and has the potential to impact studies of nanoscale physical systems in a similar manner [10, 11]. Here we demonstrate this potential with a nanophotonic optomechanical torque magnetometer and radiofrequency (RF) magnetic susceptometer. Exquisite readout sensitivity provided by a nanocavity integrated within a torsional nanomechanical resonator enables observations of the unique net magnetization and RF-driven responses of single mesoscopic magnetic structures in ambient conditions. The magnetic moment resolution is sufficient for observation of Barkhausen steps in the magnetic hysteresis of a lithographically patterned permalloy island [12]. In addition, significantly enhanced RF susceptibility is found over narrow field ranges and attributed to thermally assisted driven hopping of a magnetic vortex core between neighboring pinning sites [13]. The on-chip magneto-susceptometer scheme offers a promising path to powerful integrated cavity optomechanical devices for quantitative characterization of magnetic micro- and nanosystems in science and technology. △ Less

Submitted 2 November, 2016; v1 submitted 10 May, 2016; originally announced May 2016.

Comments: 7 pages, 4 figures

Journal ref: Nature Nanotechnology (2016)

Single-crystal diamond low-dissipation cavity optomechanics

Authors: Matthew Mitchell, Behzad Khanaliloo, David P. Lake, Tamiko Masuda, J. P. Hadden, Paul E. Barclay

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… ▽ More 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. △ Less

Submitted 12 October, 2016; v1 submitted 13 November, 2015; originally announced November 2015.

Comments: 12 pages, 5 figures

Journal ref: Optica 3, 963-970 (2016)

Effects of fabrication methods on spin relaxation and crystallite quality in Tm-doped Y$_2$Al$_5$O$_{12}$ powders studied using spectral hole burning

Authors: Thomas Lutz, Lucile Veissier, Charles W. Thiel, Philip J. T. Woodburn, Rufus L. Cone, Paul E. Barclay, Wolfgang Tittel

Abstract: High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost fabrication and a greater range of accessible material systems. Here we show that crystal properties, such as nuclear spin lifetime, are strongly… ▽ More High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost fabrication and a greater range of accessible material systems. Here we show that crystal properties, such as nuclear spin lifetime, are strongly affected by mechanical treatment, and that spectral hole burning can serve as a sensitive method to characterize the quality of REI doped powders. We focus on the specific case of thulium doped Y$_2$Al$_5$O$_{12}$ (Tm:YAG). Different methods for obtaining the powders are compared and the influence of annealing on the spectroscopic quality of powders is investigated on a few examples. We conclude that annealing can reverse some detrimental effects of powder fabrication and, in certain cases, the properties of the bulk material can be reached. Our results may be applicable to other impurities and other crystals, including color centers in nano-structured diamond. △ Less

Submitted 27 April, 2016; v1 submitted 25 September, 2015; originally announced September 2015.

Comments: 7 pages 5 figures, Science and Technology of Advanced Materials, Volume 17, Issue 1, 2016

Modification of phonon processes in nanostructured rare-earth-ion-doped crystals

Authors: Thomas Lutz, Lucile Veissier, Charles W. Thiel, Rufus L. Cone, Paul E. Barclay, Wolfgang Tittel

Abstract: Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable or improve persistent spectral hole-burning and coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped cryst… ▽ More Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable or improve persistent spectral hole-burning and coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and optical quantum memories. As an example, we discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the convenient telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y2SiO5, a widely-used material in current quantum memory research. △ Less

Submitted 27 June, 2016; v1 submitted 9 April, 2015; originally announced April 2015.

Comments: 6 pages, 4 figures

Journal ref: Phys. Rev. A 94, 013801 (2016)

Single crystal diamond nanobeam waveguide optomechanics

Authors: Behzad Khanaliloo, Harishankar Jayakumar, Aaron C. Hryciw, David P. Lake, Hamidreza Kaviani, Paul E. Barclay

Abstract: 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… ▽ More 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-$μ$W absorbed optical power, demonstrating the potential for optomechanical excitation and manipulation of diamond nanomechanical structures. △ Less

Submitted 28 April, 2015; v1 submitted 5 February, 2015; originally announced February 2015.

Comments: Minor changes. Corrected error in units of applied stress in Fig. 10

Journal ref: Phys. Rev. X 5, 041051 (2015)

Nonlinear optomechanical paddle nanocavities

Authors: Hamidreza Kaviani, Chris Healey, Marcelo Wu, Roohollah Ghobadi, Aaron Hryciw, Paul E. Barclay

Abstract: Nonlinear optomechanical coupling is the basis for many potential future experiments in quantum optomechanics (e.g., quantum non-demolition measurements, preparation of non-classical states), which to date have been difficult to realize due to small non-linearity in typical optomechanical devices. Here we introduce an optomechanical system combining strong nonlinear optomechanical coupling, low ma… ▽ More Nonlinear optomechanical coupling is the basis for many potential future experiments in quantum optomechanics (e.g., quantum non-demolition measurements, preparation of non-classical states), which to date have been difficult to realize due to small non-linearity in typical optomechanical devices. Here we introduce an optomechanical system combining strong nonlinear optomechanical coupling, low mass and large optical mode spacing. This nanoscale "paddle nanocavity" supports mechanical resonances with hundreds of fg mass which couple nonlinearly to optical modes with a quadratic optomechanical coupling coefficient $g^{(2)} > 2π\times400$ MHz/nm$^2$, and a two phonon to single photon optomechanical coupling rate $Δω_0 > 2π\times 16$ Hz. This coupling relies on strong phonon-photon interactions in a structure whose optical mode spectrum is highly non--degenerate. Nonlinear optomechanical readout of thermally driven motion in these devices should be observable for T $> 50 $ mK, and measurement of phonon shot noise is achievable. This shows that strong nonlinear effects can be realized without relying on coupling between nearly degenerate optical modes, thus avoiding parasitic linear coupling present in two mode systems. △ Less

Submitted 24 February, 2015; v1 submitted 14 December, 2014; originally announced December 2014.

Comments: 8 pages, 5 figures

Journal ref: Optica, 2, 271-274 (2015)

Near-field tuning of optomechanical coupling in a split-beam nanocavity

Authors: Aaron C. Hryciw, Marcelo Wu, Behzad Khanaliloo, Paul E. Barclay

Abstract: Tunable evanescent coupling is used to modify the optomechanical interactions within a split-beam photonic crystal nanocavity. An optical fiber taper probe is used to renormalize the optical nanocavity field and introduce a dissipative optomechanical coupling channel, reconfiguring and enhancing coupling between the optical and mechanical resonances of the device. Positioning of the fiber taper al… ▽ More Tunable evanescent coupling is used to modify the optomechanical interactions within a split-beam photonic crystal nanocavity. An optical fiber taper probe is used to renormalize the optical nanocavity field and introduce a dissipative optomechanical coupling channel, reconfiguring and enhancing coupling between the optical and mechanical resonances of the device. Positioning of the fiber taper allows preferential coupling to specific mechanical modes and provides a mechanism for tuning the optomechanical interaction between dissipative and dispersive coupling regimes. △ Less

Submitted 1 July, 2014; originally announced July 2014.

Comments: Manuscript (5 pages, 4 figures) with included Supplemental Material (5 pages, 3 figures)

Dissipative and Dispersive Optomechanics in a Nanocavity Torque Sensor

Authors: Marcelo Wu, Aaron C. Hryciw, Chris Healey, David P. Lake, Harishankar Jayakumar, Mark R. Freeman, John P. Davis, Paul E. Barclay

Abstract: Dissipative and dispersive optomechanical couplings are experimentally observed in a photonic crystal split-beam nanocavity optimized for detecting nanoscale sources of torque. Dissipative coupling of up to approximately $500$ MHz/nm and dispersive coupling of $2$ GHz/nm enable measurements of sub-pg torsional and cantilever-like mechanical resonances with a thermally-limited torque detection sens… ▽ More Dissipative and dispersive optomechanical couplings are experimentally observed in a photonic crystal split-beam nanocavity optimized for detecting nanoscale sources of torque. Dissipative coupling of up to approximately $500$ MHz/nm and dispersive coupling of $2$ GHz/nm enable measurements of sub-pg torsional and cantilever-like mechanical resonances with a thermally-limited torque detection sensitivity of 1.2$\times 10^{-20} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in ambient conditions and 1.3$\times 10^{-21} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in low vacuum. Interference between optomechanical coupling mechanisms is observed to enhance detection sensitivity and generate a mechanical-mode-dependent optomechanical wavelength response. △ Less

Submitted 5 September, 2014; v1 submitted 25 March, 2014; originally announced March 2014.

Comments: 11 pages, 6 figures

Journal ref: Phys. Rev. X 4 , 021052 (2014)

Cavity optomechanics in gallium phosphide microdisks

Authors: Matthew Mitchell, Aaron C. Hryciw, Paul E. Barclay

Abstract: We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors $ > 2.8\times10^{5}$ and mode volumes $< 10 (λ/n)^3$, and study their nonlinear and optomechanical properties. For optical intensities up to $8.0\times10^4$ intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites… ▽ More We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors $ > 2.8\times10^{5}$ and mode volumes $< 10 (λ/n)^3$, and study their nonlinear and optomechanical properties. For optical intensities up to $8.0\times10^4$ intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 $μ$m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate $g_0/2π\sim 30$ kHz for the fundamental mechanical radial breathing mode at 488 MHz. △ Less

Submitted 29 May, 2014; v1 submitted 24 September, 2013; originally announced September 2013.

Comments: Published Version

Journal ref: Appl. Phys. Lett. 104, 141104 (2014)

Optical design of split-beam photonic crystal nanocavities

Authors: Aaron C. Hryciw, Paul E. Barclay

Abstract: We design high quality factor photonic crystal nanobeam cavities formed by two mechanically isolated cantilevers. These "split-beam" cavities have a physical gap at the center, allowing mechanical excitations of one or both of the cavity halves. They are designed by analyzing the optical band structures and mode profiles of waveguides perforated by elliptical holes and rectangular gaps, and are pr… ▽ More We design high quality factor photonic crystal nanobeam cavities formed by two mechanically isolated cantilevers. These "split-beam" cavities have a physical gap at the center, allowing mechanical excitations of one or both of the cavity halves. They are designed by analyzing the optical band structures and mode profiles of waveguides perforated by elliptical holes and rectangular gaps, and are predicted to support optical resonances with quality factors exceeding 1E6 at wavelengths of ~ 1.6 um. △ Less

Submitted 17 April, 2013; v1 submitted 2 January, 2013; originally announced January 2013.

Comments: To appear in Optics Letters

Nanoscale Torsional Optomechanics

Authors: P. H. Kim, C. Doolin, B. D. Hauer, A. J. R. MacDonald, M. R. Freeman, P. E. Barclay, J. P. Davis

Abstract: Optomechanical transduction is demonstrated for nanoscale torsional resonators evanescently coupled to optical microdisk whispering gallery mode resonators. The on-chip, integrated devices are measured using a fully fiber-based system, including a tapered and dimpled optical fiber probe. With a thermomechanically calibrated optomechanical noise floor down to 7 fm/sqrt(Hz), these devices open the d… ▽ More Optomechanical transduction is demonstrated for nanoscale torsional resonators evanescently coupled to optical microdisk whispering gallery mode resonators. The on-chip, integrated devices are measured using a fully fiber-based system, including a tapered and dimpled optical fiber probe. With a thermomechanically calibrated optomechanical noise floor down to 7 fm/sqrt(Hz), these devices open the door for a wide range of physical measurements involving extremely small torques, as little as 4x10^-20 N*m. △ Less

Submitted 17 November, 2012; v1 submitted 5 October, 2012; originally announced October 2012.

Comments: 4 pages, 4 figures - Accepted to APL Oct 22nd, 2012. To appear in February 4th issue - as cover article

Journal ref: Appl. Phys. Lett. 102, 053102 (2013)

Hybrid nanocavities for resonant enhancement of color center emission in diamond

Authors: Paul E. Barclay, Kai-Mei C. Fu, Charles Santori, Andrei Faraon, Raymond G. Beausoleil

Abstract: Resonantly enhanced emission from the zero phonon line of a diamond nitrogen-vacancy (NV) center in single crystal diamond is demonstrated experimentally using a hybrid whispering gallery mode nanocavity. A 900 nm diameter ring nanocavity formed from gallium phosphide, whose sidewalls extend into a diamond substrate, is tuned onto resonance at low-temperature with the zero phonon line of a negativ… ▽ More Resonantly enhanced emission from the zero phonon line of a diamond nitrogen-vacancy (NV) center in single crystal diamond is demonstrated experimentally using a hybrid whispering gallery mode nanocavity. A 900 nm diameter ring nanocavity formed from gallium phosphide, whose sidewalls extend into a diamond substrate, is tuned onto resonance at low-temperature with the zero phonon line of a negatively charged NV center implanted near the diamond surface. When the nanocavity is on resonance, the zero phonon line intensity is enhanced by approximately an order of magnitude, and the spontaneous emission lifetime of the NV is reduced as much as 18%, corresponding to a 6.3X enhancement of emission in the zero photon line. △ Less

Submitted 25 May, 2011; originally announced May 2011.

Journal ref: Phys. Rev. X 1, 011007 (2011)

Conversion of neutral nitrogen-vacancy centers to negatively-charged nitrogen-vacancy centers through selective oxidation

Authors: K. -M. C. Fu, C. Santori, P. E. Barclay, R. G. Beausoleil

Abstract: The conversion of neutral nitrogen-vacancy centers to negatively charged nitrogen-vacancy centers is demonstrated for centers created by ion implantation and annealing in high-purity diamond. Conversion occurs with surface exposure to an oxygen atmosphere at 465 C. The spectral properties of the charge-converted centers are investigated. Charge state control of nitrogen-vacancy centers close to… ▽ More The conversion of neutral nitrogen-vacancy centers to negatively charged nitrogen-vacancy centers is demonstrated for centers created by ion implantation and annealing in high-purity diamond. Conversion occurs with surface exposure to an oxygen atmosphere at 465 C. The spectral properties of the charge-converted centers are investigated. Charge state control of nitrogen-vacancy centers close to the diamond surface is an important step toward the integration of these centers into devices for quantum information and magnetic sensing applications. △ Less

Submitted 29 January, 2010; originally announced January 2010.

Comments: 4 pages, 3 figures

Observation of the dynamic Jahn-Teller effect in the excited states of nitrogen-vacancy centers in diamond

Authors: Kai-Mei C. Fu, Charles Santori, Paul E. Barclay, Lachlan J. Rogers, Neil B. Manson, Raymond G. Beausoleil

Abstract: The optical transition linewidth and emission polarization of single nitrogen-vacancy (NV) centers are measured from 5 K to room temperature. Inter-excited state population relaxation is shown to broaden the zero-phonon line and both the relaxation and linewidth are found to follow a T^5 dependence for T up to 100 K. This dependence indicates that the dynamic Jahn-Teller effect is the dominant d… ▽ More The optical transition linewidth and emission polarization of single nitrogen-vacancy (NV) centers are measured from 5 K to room temperature. Inter-excited state population relaxation is shown to broaden the zero-phonon line and both the relaxation and linewidth are found to follow a T^5 dependence for T up to 100 K. This dependence indicates that the dynamic Jahn-Teller effect is the dominant dephasing mechanism for the NV optical transitions at low temperatures. △ Less

Submitted 17 December, 2009; v1 submitted 2 October, 2009; originally announced October 2009.

Journal ref: Phys. Rev. Lett. 103, 256404 (2009)

Chip-based microcavities coupled to NV centers in single crystal diamond

Authors: Paul E. Barclay, Kai-Mei C. Fu, Charles Santori, Raymond G. Beausoleil

Abstract: Optical coupling of nitrogen vacancy centers in single-crystal diamond to an on-chip microcavity is demonstrated. The microcavity is fabricated from a hybrid gallium phosphide and diamond material system, and supports whispering gallery mode resonances with spectrometer resolution limited Q > 25000. Optical coupling of nitrogen vacancy centers in single-crystal diamond to an on-chip microcavity is demonstrated. The microcavity is fabricated from a hybrid gallium phosphide and diamond material system, and supports whispering gallery mode resonances with spectrometer resolution limited Q > 25000. △ Less

Submitted 14 August, 2009; originally announced August 2009.

Journal ref: Appl. Phys. Lett. 95, 191115 (2009)

Hybrid photonic crystal cavity and waveguide for coupling to diamond NV-centers

Authors: Paul E. Barclay, Kai-Mei Fu, Charles Santori, Raymond G. Beausoleil

Abstract: A design for an ultra-high Q photonic crystal nanocavity engineered to interact with nitrogen-vacancy (NV) centers located near the surface of a single crystal diamond sample is presented. The structure is based upon a nanowire photonic crystal geometry, and consists of a patterned high refractive index membrane, such as gallium phosphide (GaP), supported by a diamond substrate. The nanocavity s… ▽ More A design for an ultra-high Q photonic crystal nanocavity engineered to interact with nitrogen-vacancy (NV) centers located near the surface of a single crystal diamond sample is presented. The structure is based upon a nanowire photonic crystal geometry, and consists of a patterned high refractive index membrane, such as gallium phosphide (GaP), supported by a diamond substrate. The nanocavity supports a mode with quality factor Q > 1.5 million and mode volume V < 0.52 (λ/n_\text{GaP})^3, and promises to allow Purcell enhanced collection of spontaneous emission from an NV located more than 50 nm below the diamond surface. The nanowire photonic crystal waveguide can be used to efficiently couple light into and out of the cavity, or as an efficient broadband collector of NV phonon sideband emission. The proposed structures can be fabricated using existing materials and processing techniques. △ Less

Submitted 22 May, 2009; v1 submitted 2 April, 2009; originally announced April 2009.

Journal ref: Optics Express, Vol. 17, Issue 12, pp. 9588-9601 (2009)

High nitrogen-vacancy density diamonds for magnetometry applications

Authors: V. M. Acosta, E. Bauch, M. P. Ledbetter, C. Santori, K. -M. C. Fu, P. E. Barclay, R. G. Beausoleil, H. Linget, J. F. Roch, F. Treussart, S. Chemerisov, W. Gawlik, D. Budker

Abstract: Nitrogen-vacancy (NV) centers in millimeter-scale diamond samples were produced by irradiation and subsequent annealing under varied conditions. The optical and spin relaxation properties of these samples were characterized using confocal microscopy, visible and infrared absorption, and optically detected magnetic resonance. The sample with the highest NV- concentration, approximately 16 ppm = 2… ▽ More Nitrogen-vacancy (NV) centers in millimeter-scale diamond samples were produced by irradiation and subsequent annealing under varied conditions. The optical and spin relaxation properties of these samples were characterized using confocal microscopy, visible and infrared absorption, and optically detected magnetic resonance. The sample with the highest NV- concentration, approximately 16 ppm = 2.8 x 10^{18} cm^{-3}, was prepared with no observable traces of neutrally-charged vacancy defects. The effective transverse spin relaxation time for this sample was T2* = 118(48) ns, predominately limited by residual paramagnetic nitrogen which was determined to have a concentration of 52(7) ppm. Under ideal conditions, the shot-noise limited sensitivity is projected to be ~150 fT/\sqrt{Hz} for a 100 micron-scale magnetometer based on this sample. Other samples with NV- concentrations from .007 to 12 ppm and effective relaxation times ranging from 27 to 291 ns were prepared and characterized. △ Less

Submitted 31 July, 2009; v1 submitted 19 March, 2009; originally announced March 2009.

Comments: Accepted by PRB (July 29, 2009), 24 pages, 10 figures, 3 tables

Journal ref: Phys.Rev.B80:115202,2009

Vertical distribution of nitrogen-vacancy centers in diamond formed by ion implantation and annealing

Authors: Charles Santori, Paul E. Barclay, Kai-Mei C. Fu, Raymond G. Beausoleil

Abstract: Etching experiments were performed that reveal the vertical distribution of optically active nitrogen-vacancy (NV) centers in diamond created in close proximity to a surface through ion implantation and annealing. The NV distribution depends strongly on the native nitrogen concentration, and spectral measurements of the neutral and negatively-charged NV peaks give evidence for electron depletion… ▽ More Etching experiments were performed that reveal the vertical distribution of optically active nitrogen-vacancy (NV) centers in diamond created in close proximity to a surface through ion implantation and annealing. The NV distribution depends strongly on the native nitrogen concentration, and spectral measurements of the neutral and negatively-charged NV peaks give evidence for electron depletion effects in lower-nitrogen material. The results are important for potential quantum information and magnetometer devices where NV centers must be created in close proximity to a surface for coupling to optical structures. △ Less

Submitted 8 February, 2009; v1 submitted 19 December, 2008; originally announced December 2008.

Comments: 9 pages, 6 figures

Nonlinear absorption and dispersion in fiber-taper-coupled silicon photonic crystal microresonators

Authors: Paul E. Barclay, Kartik Srinivasan, Oskar Painter

Abstract: A technique is demonstrated which efficiently transfers light between a tapered standard single-mode optical fiber and a high-Q, ultra-small mode volume, silicon photonic crystal resonant cavity. Cavity mode quality factors of 47000 are measured, and a total fiber-to-cavity coupling efficiency of 44% is demonstrated. Using this efficient cavity input and output channel, the steady-state nonlinea… ▽ More A technique is demonstrated which efficiently transfers light between a tapered standard single-mode optical fiber and a high-Q, ultra-small mode volume, silicon photonic crystal resonant cavity. Cavity mode quality factors of 47000 are measured, and a total fiber-to-cavity coupling efficiency of 44% is demonstrated. Using this efficient cavity input and output channel, the steady-state nonlinear absorption and dispersion of the photonic crystal cavity is studied. Optical bistability is observed for fiber input powers as low as 250 μW, corresponding to a dropped power of 100 μW and 3 fJ of stored cavity energy. A high-density effective free-carrier lifetime for these silicon photonic crystal resonators of 0.5 ns is also estimated from power dependent loss and dispersion measurements. △ Less

Submitted 30 November, 2004; originally announced December 2004.

Journal ref: Optics Express, Vol. 13, No. 3, pp. 801-820, Feb. 7, 2005