Solid-state spin systems including nitrogen-vacancy (NV) centers in diamond constitute an increasingly favored quantum sensing platform. However, present NV ensemble devices exhibit sensitivities orders of magnitude away from theoretical limits. The sensitivity shortfall both handicaps existing implementations and curtails the envisioned application space. This review analyzes proposed approaches to enhance broadband ensemble-NV-diamond magnetometers. Improvements dephasing time, readout...

Significance We demonstrate noninvasive detection of action potentials with single-neuron sensitivity, including in whole organisms. Our sensor is composed quantum defects within a diamond chip, which detect time-varying magnetic fields generated by potentials. The biocompatible and can be brought into close proximity to the organism without adverse effect, allowing for long-term observation superior resolution neuron fields. Optical also provides information about potential propagation that...

We present a combined theoretical and experimental study of solid-state spin decoherence in an electronic bath, focusing specifically on ensembles nitrogen vacancy (NV) color centers diamond the associated substitutional bath. perform measurements NV free induction decay times $T_2^*$ spin-echo coherence $T_2$ 25 samples with concentrations [N] ranging from 0.01 to 300\,ppm. introduce microscopic model numerical simulations quantitatively explain degradation both over four orders magnitude...

We demonstrate a scheme for optical cycling in the polar, diatomic molecule strontium monofluoride (SrF) using ${X}^{2}{\ensuremath{\Sigma}}^{+}\ensuremath{\rightarrow}{A}^{2}{\ensuremath{\Pi}}_{1/2}$ electronic transition. SrF's highly diagonal Franck-Condon factors suppress vibrational branching. eliminate rotational branching by employing quasicycling $N=1\ensuremath{\rightarrow}{N}^{\ensuremath{'}}=0$ type transition conjunction with magnetic field remixing of dark Zeeman sublevels....

We report direct observation of controlled and reversible switching magnetic domains using static (dc) electric fields applied in situ during Lorentz microscopy. The is realized through electromechanical coupling thin film Fe0.7Ga0.3/BaTiO3 bilayer structures mechanically released from the growth substrate. domain wall motion observed dynamically, allowing association local ordering throughout a range fields. During application ∼7−11 MV/m to piezoelectric BaTiO3 film, rearrange ferromagnetic...

We demonstrate deceleration of a beam neutral strontium monofluoride molecules using radiative forces. Under certain conditions, the results in substantial flux detected with velocities ≲50 m/s. Simulations and other data indicate that detection below this velocity is greatly diminished by transverse divergence from beam. The observed slowing, ∼140 m/s, corresponds to scattering ≳10(4) photons. also observe longitudinal compression under different conditions. Combined molecular laser cooling...

Quantum spin dephasing is caused by inhomogeneous coupling to the environment, with resulting limits measurement time and precision of spin-based sensors. The effects can be especially pernicious for dense ensembles electronic spins in solid-state, such as nitrogen-vacancy (NV) color centers diamond. We report use two complementary techniques, bath control double quantum coherence, enhance ($T_2^*$) NV more than an order magnitude. In combination, these techniques (i) eliminate dominant...

Magnetic resonance imaging (MRI) is a widely used biomedical modality that derives much of its contrast from microscale magnetic field gradients in biological tissues. However, the connection between these sub-voxel patterns and MRI has not been studied experimentally. Here, we describe new method to map subcellular fields mammalian cells tissues using nitrogen vacancy diamond magnetometry connect maps voxel-scale contrast, providing insights for vivo agent design.

Real-time sensing of dynamic vector magnetic fields is used in areas ranging from navigation to biocurrent imaging. Many magnetometers measure only a single field component at time, and may suffer orientation errors. Employing frequency-multiplexing technique with an ensemble nitrogen-vacancy centers diamond, the authors present device that measures $a\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}l$ components once, operating high bandwidth top-notch sensitivity. With low implementation...

Quantum sensing with solid-state spins offers the promise of high spatial resolution, bandwidth, and dynamic range at sensitivities comparable to more mature quantum technologies, such as atomic vapor cells superconducting devices. However, despite theoretical sensitivity limits, performance bulk sensors has so far lagged behind these alternatives. A recent review [Barry et al., Rev. Mod. Phys. 92, 015004 (2020)] suggests several paths improve magnetometers employing nitrogen-vacancy defects...

Abstract Overcoming poor readout is an increasingly urgent challenge for devices based on solid-state spin defects, particularly given their rapid adoption in quantum sensing, information, and tests of fundamental physics. However, spite experimental progress specific systems, sensors still lack a universal, high-fidelity technique. Here we demonstrate high-fidelity, room-temperature ensemble nitrogen-vacancy centers via strong coupling to dielectric microwave cavity, building similar...

Magnetometry with diamond nitrogen-vacancy (NV) ensembles has enabled devices picotesla sensitivity at static and low-frequency fields, but their performance higher frequencies lags far behind. The authors solve the technical challenges demonstrate a microwave-frequency NV magnetometer sensitivity, by implementing pulse scheme for noise cancellation employing custom-grown diamond. This enhancement could be extended into broader range of using spin-locking quantum frequency mixing. These...

We demonstrate and characterize a cryogenic buffer gas-cooled molecular beam source capable of producing bright beams free radicals refractory species. Details the properties (brightness, forward velocity distribution, transverse spread, rotational vibrational temperatures) are measured under varying conditions for species SrF. Under typical we produce brightness 1.2 × 10(11) molecules/sr/pulse in X(2)Σ(+)(v = 0, N(rot) 0) state, with 140(m/s) temperature ≈ 1 K. This compares favorably to...

Nitrogen-vacancy centers in diamond are promising as sensitive vector magnetometers, quantum repeaters, and qubits, but realizing this potential has been limited by the material itself. Here a comprehensive study addresses creation of nitrogen-vacancy centers, balancing impact irradiation annealing on coherence properties commercial material. Photoluminescence decomposition analysis is used to quantitatively determine neutral-to-negative charge-state ratio, for insight into electron properties.

We present an S-band tunable loop gap resonator (LGR) providing strong, homogeneous, and directionally uniform broadband microwave (MW) drive for nitrogen-vacancy (NV) ensembles. With 42 dBm of input power, the composite device provides field amplitudes approaching 5 G over a circular area $\gtrsim\!50$ mm$^2$ or cylindrical volume $\gtrsim\!250$ mm$^3$. The wide 80 MHz bandwidth allows driving all eight NV Zeeman resonances bias magnetic fields below 20 G. For pulsed applications realizes...

We report experiments demonstrating the laser cooling of a diatomic molecule. A cryogenic molecular beam strontium monofluoride (SrF) is subjected to one-dimensional transverse cooling. observe both Doppler and Sisyphus-type mechanisms.

Radiative forces from near-resonant laser light can be used for cooling and slowing the motion of diatomic molecules. While radiative-force efficient in reducing longitudinal velocity molecules a beam, this method has so far resulted relatively low fluxes slow available loading into trap. This is primarily due to divergence molecular which increases inverse proportion forward velocity. In paper, we discuss methods transversely confine as they are slowed by radiative forces. We focus...

Precision optical measurements of the electron-spin precession nitrogen-vacancy (NV) centers in diamond form basis numerous applications. The most sensitivity-demanding applications, such as femtotesla magnetometry, require ability to measure changes GHz spin transition frequencies at sub-millihertz level, corresponding a fractional resolution better than <a:math...

We describe the design and implementation of a low-cost, FPGA-based servo controller with an integrated waveform synthesizer lock-in amplifier. This system has been designed specific application laser frequency locking in mind but should be adaptable to variety other purposes as well. The incorporates onboard synthesizer, amplifier, two channels proportional-integral (PI) control, ramp generator on single FPGA chip. is based inexpensive, off-the-shelf evaluation board wide available...

Quantum sensors offer unparalleled precision, accuracy, and sensitivity for a variety of measurement applications. We report compact magnetometer based on ferrimagnetic sensing element in an oscillator architecture that circumvents challenges common to other quantum approaches such as limited dynamic range, bandwidth, dependence vacuum, cryogenic, or laser components. The device exhibits fixed, calibration-free response governed by the electron gyromagnetic ratio. Exchange narrowing material...

We demonstrate a simple and easy method for producing low-reflectivity surfaces that are ultra-high vacuum compatible, may be baked to high temperatures, easily applied even on complex surface geometries. Black cupric oxide (CuO) chemically grown in minutes any copper surface, allowing low-cost, rapid prototyping, production. The reflective properties measured comparable commercially available products creating optically black surfaces. describe apparatus which uses multiple blackened...