Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session S08: Atomic Magnetometers and Sensors |
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Chair: Thad Walker, University of Wisconsin Room: Grand F |
Thursday, May 31, 2018 2:00PM - 2:12PM |
S08.00001: Spin-based characterization of material properties of diamond samples for high-sensitivity NV magnetometry Diana Prado Lopes Aude Craik, Andrew Greenspon, Jennifer Schloss, Connor Hart, Erik Bauch, Pauli Kehayias, Xingyu Zhang, Patrick Scheidegger, Matthew Turner, Evelyn Hu, Ronald Walsworth Using optical spectroscopy and spin-manipulation techniques, we characterize the nitrogen concentration and charge-state ratio of nitrogen-vacancy (NV) defects in a collection of diamond samples. We use the data both to calibrate a purely spin-based measurement toolbox for characterizing spin concentrations in diamond and to identify ways of optimizing parameters in diamond growth and processing in order to produce samples with a high concentration of negatively-charged NV defects, for use in high-sensitivity NV-ensemble-based magnetometry. [Preview Abstract] |
Thursday, May 31, 2018 2:12PM - 2:24PM |
S08.00002: Comagnetometry Using Synchronous Spin Exchange Optical Pumping Daniel Thrasher, Susan Sorensen, Josh Weber, Anna Korver, Thad Walker We demonstrate comagnetometry using synchronous spin exchange optical pumping of two Xe isotopes with Rb. Both isotopes are simultaneously polarized transverse to a pulsed bias magnetic field through spin exchange collisions with polarized Rb atoms. The bias field is applied as a sequence of alkali 2$\pi $ pulses, which allows the magnetometer to operate at near spin exchange relaxation free sensitivity. The Rb atoms are optically pumped transverse to the bias field, greatly suppressing the alkali field's contribution to bias instability. The Rb polarization is simultaneously modulated at the nuclear magnetic resonance of each Xe isotope. We will present a detailed analysis of systematic errors. [Preview Abstract] |
Thursday, May 31, 2018 2:24PM - 2:36PM |
S08.00003: Atomic-candle techniques beyond the small-signal regime Andrei Tretiakov, Lindsay LeBlanc Applying a phase-modulated AC magnetic signal at a frequency near the hyperfine splitting of an atom forces the steady-state population to oscillate at integer harmonics of the modulation frequency. Resonance behaviour of the first two harmonics near the Rabi frequency, known as $\alpha$ and $\beta$ Rabi resonances, is widely used for microwave field magnetometry and as a power standard, known as the atomic candle. Unlike in previous work, here we explore the Rabi resonances beyond the small-signal approximation using computer simulation and report experimental observations of higher harmonics in cold $^{87}$Rb atoms. This will allow us to relax the small-signal assumption and possibly exploit the higher-order harmonics in order to improve precision of magnetometers and power standards based on the atomic candle technique. [Preview Abstract] |
Thursday, May 31, 2018 2:36PM - 2:48PM |
S08.00004: High-sensitivity wide-field magnetic field imaging using NV-diamond Connor Hart, Patrick Scheidegger, Erik Bauch, Jennifer Schloss, Matthew Turner, Ronald Walsworth We present the first implementation of wide-field magnetic imaging based on the Ramsey protocol and a high density layer of nitrogen-vacancy (NV) color centers at the surface of a diamond chip. Compared to standard CW techniques for optically detected magnetic resonance (ODMR), our pulsed implementation provides enhanced sensitivity, a higher sensing bandwidth (up to \textasciitilde 100 kHz), and better noise rejection. By extending the standard Ramsey sensing scheme with advanced quantum control methods, including sensing in the NV center's double-quantum basis \textbraceleft -1,$+$1\textbraceright and spin bath control, we significantly reduce the imager's susceptibility to inhomogeneities such as crystal-lattice strain fields and microwave gradients over of the field-of-view. [Preview Abstract] |
Thursday, May 31, 2018 2:48PM - 3:00PM |
S08.00005: Nuclear Magnetic Dipole Frequency Shifts in a 3He-129Xe Comagnetometer Mark Limes, Nezih Dural, Michael Romalis, Elizabeth Foley, Tom Kornack We report on the operation of a $^3$He-$^{129}$Xe comagnetometer in 2-mm sized anodically bonded cells with a 300 s spin coherence time for $^{129}$Xe. We use a series of batch-fabricated cells with well-defined cylindrical geometries to measure the frequency shifts due to nuclear magnetic dipole fields. We find that these frequency shifts, which cause instabilities in the operation of vapor-cell comagnetometers, can be nulled out in certain geometries. Using this control we investigate the isotropic spin-spin coupling between the two noble-gas nuclei. [Preview Abstract] |
Thursday, May 31, 2018 3:00PM - 3:12PM |
S08.00006: Magnetic field mapping and the detection of explosives using radio-frequency atomic magnetometers Robert Cooper, David Prescott, Karen Sauer Magnetic field mapping from an array of magnetometers is used to distinguish local from far away sources. The magnetometer's Larmor frequency is easily tuned to the signal of interest using a small DC magnetic field. Of interest is the detection of unique radio-frequency signals from an explosive arising during nuclear quadrupole resonance. The signals are however weak, on the order of fT, and can be swamped by interference in an unshielded environment. Optically pumped $^{\mathrm{87}}$Rb vapor cells are used to detect fT size signals with background interference up to 200 times larger at a frequency 2 Hz off of the cell's Larmor frequency. Four cells with a baseline of 25 cm allow the detection of local sources on inner sensors while suppressing constant and linear interference present on all four cells. Critical to robust interference rejection is calibration of the sensors in real-time to compensate for a changing magnetic environment. A phase-encoded reference signal uniquely identifies it from other sources and can be applied continuously. To be effective, however, the reference signal itself must be well calibrated. Electron spin-resonance used for this calibration is unexpectedly found to be polarization dependent under certain conditions. [Preview Abstract] |
Thursday, May 31, 2018 3:12PM - 3:24PM |
S08.00007: Entanglement-enhanced sensing with electronic spins in diamond Won Kyu Calvin Sun, Alexandre Cooper, Jean-Christophe Jaskula, Paola Cappellaro Entanglement-enhanced sensing promises sensitivities beyond the standard quantum limit (SQL), but requires robust control to prepare entangled states with high fidelity. Operationally, one must be able to initialize a quantum system to a state of low entropy (ideally a pure state) and perform an entangling gate while protecting the state against dissipation. These steps are usually challenging and imperfections might overshadow the advantage given by entanglement. In this work, we aim at measuring magnetic fields with sensitivity beyond the SQL with two electronic spins associated with a single nitrogen-vacancy center and a paramagnetic center in diamond. To achieve a state of low entropy—that is, a state of high polarization—we optimize the performance of a single polarization transfer block, and further show that imperfect repetitive transfers can increase the total polarization. Then to create the desired entangled state with high fidelity, we compare the performance of two entangling gates with varying dependence on decoherence channels and control errors. Our work not only demonstrates that entanglement-enhanced sensing in the solid-state is possible, but also introduces strategies to robustly achieve high-fidelity initialization and entanglement in larger quantum registers. [Preview Abstract] |
Thursday, May 31, 2018 3:24PM - 3:36PM |
S08.00008: Alkali atoms in solid parahydrogen Sunil Upadhyay, Jonathan Weinstein We grow solid parahydrogen matrices doped with alkali atoms at densities from $10^{16}$ to $10^{18}$~cm$^{-3}$. We prepare the atomic spin state of the implanted atoms with optical pumping, and measure the spin state with optical spectroscopy. The combination of high atomic densities, optical addressability, and long coherence times make this a promising experimental platform for applications such as magnetometry. We compare optical properties and spin coherence for different alkali atoms. [Preview Abstract] |
Thursday, May 31, 2018 3:36PM - 3:48PM |
S08.00009: Quantum sensing in the physically rotating frame Robert Scholten, Alexander Wood, Alex Aeppli, Emmanuel Lilette, Yaakov Fein, Viktor Perunicic, Lloyd Hollenberg, Andy Martin We describe quantum measurement and control of nitrogen vacancy (NV) center qubits in rapidly rotating diamond. The rotation period is comparable to the qubit electron spin coherence time T2, allowing detection of rotationally-induced magnetic pseudo-fields acting on a bath of proximal 13C nuclear spins (Nature Physics doi:10.1038/nphys4221). By rotating the diamond at rates comparable to the nuclear spin precession frequency (\textgreater 100,000 rpm) we can induce pseudo-fields large enough to cancel the conventional magnetic field for the nuclear spins while having minimal effect on the NV qubits. Our results highlight the profound connection between magnetism and physical rotation, and establish a novel way of controlling the nuclear spin bath surrounding the NV center. We discuss future work involving control of single NV qubits in a rotating diamond and possible improvements to magnetometry using rapid sensor rotation. [Preview Abstract] |
Thursday, May 31, 2018 3:48PM - 4:00PM |
S08.00010: Towards quantum-enhancement of an atomic gradiometer with multipass cells Vito Giovanni Lucivero, Nathaniel David McDonough, Wonjae Lee, Nezih Dural, Michael Romalis A major challenge in atomic quantum metrology is the use of squeezing to beat classical sensitivity of atomic sensors under optimal conditions i.e. within a high-density regime. In the context of optical magnetometry, it has been known for some time that spin squeezing induced by a quantum non demolition measurement cannot improve the long-term sensitivity, in the presence of a constant decoherence rate. However, it has been recently predicted that spin-exchange collisions in dense atomic vapor can cause nonlinear evolution of the atomic density matrix and improvement of long-term sensitivity by spin squeezing. Here we discuss recent progress towards the experimental implementation of spin squeezing to improve the sensitivity of an atomic gradiometer using multipass cells. We report nonlinear evolution of 87Rb dense ensembles, with strong polarization and high spin correlation, by using~a new generation of multipass cells. The design maintains a large effective interaction volume and significantly reduces the diffusion component of the spin time-correlation function, the latter being a requirement for the suppression of atomic spin noise by spin squeezing. [Preview Abstract] |
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