Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session C11: Atomic MagnetometryRecordings Available
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Chair: Jason Stalnaker, Oberlin College Room: Grand Ballroom E |
Tuesday, May 31, 2022 11:00AM - 11:12AM |
C11.00001: All-Optical 87Rb Magnetometer with 10 fT/√Hz and 1 fT/cm/√Hz in Earth-Field-Scale Magnetic Fields Michael D Bulatowicz, Jonas Tost, Thad G Walker We are developing a Bell-Bloom magnetometer based on pulses of optical pump light approximately resonant with the D1 optical transition in 87Rb, capable of operating in Earth-field-scale magnetic fields in an unshielded environment and exhibiting noise levels consistent with biomagnetic measurement capabilities (e.g. magnetocardiography and magnetoencephalography). The optical pump pulse repetition rate is adjusted to be on resonance with the Larmor frequency of the precessing spins by continuously monitoring the phase response of the spins relative to the optical pump pulses. When tested in a magnetically shielded environment, the single-channel demonstrated noise floor is approximately 10 fT/rtHz, and a differential pair of sensitive elements separated by a distance of approximately 9 cm demonstrated differential noise of approximately 1 fT/cm/rtHz. With closed-loop feedback and oscillating magnetic fields applied along orthogonal spatial axes, this fundamentally scalar magnetometer technology can observe the vector components of the incident magnetic field. |
Tuesday, May 31, 2022 11:12AM - 11:24AM |
C11.00002: An atomic magnetometer with quantum sensitivity limited by the longitudinal relaxation time T1 Wonjae Lee, Nezih Dural, Michael V Romalis It is usually assumed that fundamental sensitivity of any quantum measurement is limited by the coherence relaxation time T2. We demonstrate a simple measurement scheme with sensitivity limited by the population relaxation time T1. The quantum sensitivity for magnetic fields δB exhibits a Heisenberg linear scaling with number of atoms N until it reaches the standard quantum limit except with T2 time replaced by T1, δB ∝ (NT1)-1/2. Since the longitudinal relaxation time T1 is longer than T2 in most systems, it provides a general advantage for quantum measurements. We derive these results based on a simple Bloch-equation model and demonstrate them experimentally with a 87Rb atomic magnetometer. A key requirement for implementing this approach is high optical density on resonance of the atomic vapor, which enables quantum non-demolition measurements of the collective atomic spin state with high fidelity. |
Tuesday, May 31, 2022 11:24AM - 11:36AM |
C11.00003: Pulsed 87Rb vector magnetometer using a fast-rotating field Tao Wang, Wonjae Lee, Michael Romalis, Mark E Limes, Tom Kornack, Elizabeth Foley We present a vector geomagnetic magnetometer based on application of an external rotating magnetic field to a scalar atomic magnetometer. Using two channels in a gradiometer mode, it can provide simultaneous measurements of total field gradient with a sensitivity of 50 fT/Hz1/2, as well as two polar angles relative to the plane of magnetic field rotation with resolutions of 8 nrad/Hz1/2 (8 ppb, 400 fT/Hz1/2) at 50 μT. Their noise spectrums are flat down to 1 Hz and 0.1 Hz, respectively. Crucially, it avoids several metrological difficulties associated with vector magnetometers and gradiometers. We use a field rotation rate faster than the spin relaxation rate and show that it eliminates a class of systematic effects associated with heading errors in alkali-metal scalar magnetometers. We investigate several other systematic effects, such as Berry's phase frequency shift and the effects of eddy currents in nearby conductors. We also derive fundamental limits on sensitivity of such sensor and show that the vector sensitivity can approach the sensitivity of scalar atomic magnetometers. |
Tuesday, May 31, 2022 11:36AM - 11:48AM |
C11.00004: Yb atomic magnetometer with unique capabilities Tanaporn N Na Narong, Hongquan Li, Leo W Hollberg We report on a fast, sensitive atomic vector magnetometer, which relies on atomic spectroscopy and Zeeman splitting in the 3P1 state of Yb atoms. In the presence of a magnetic field gradient, we observed prominent dark stripes in the fluorescence when thermal Yb atoms are driven by square wave amplitude-modulated light. The 1S0-3P1 transition forms a "V" configuration where two laser sidebands interact with two 3P1 Zeeman sublevels simultaneously. The dark resonance occurs when the Zeeman splitting matches the frequency difference between the sidebands. We estimate the magnetic field sensitivity to be ≈1 mG with a large dynamic range from mG to kG. The contrast of the lines is readily observable by eye or camera, allowing direct imaging of the local magnetic field in 2D with a short response time of ≈10 μs. The magnetic vector orientation can be inferred from measurements with different laser polarizations. We are developing a numerical model to compute the spectra and the dark-line contrast by solving Optical Bloch Equations for a 4-level atom and multiple optical fields. The model includes the effects of Doppler broadening from the atoms’ velocity distribution, which will allow direct comparison to the experimental results and computation of a magnetic field map from the data. |
Tuesday, May 31, 2022 11:48AM - 12:00PM |
C11.00005: New Pulsed Dual-axis Alkali-metal-noble-gas Comagnetometer Jingyao Wang, Junyi Lee, Hudson Loughlin, Morgan Hedges, Michael Romalis Alkali-metal-noble-gas comagnetometers demonstrated high sensitivity to non-magnetic couplings from being in the spin-exchange relaxation free(SERF) regime, and suppressed sensitivity to magnetic field drifts. This prompted their employment as gyroscopes, and in probing axion dark matter, anomalous spin-mass and spin-spin interactions, and violations of CPT and Lorentz invariance. We report on the development of a new 87Rb-21Ne comagnetometer with pulsed optical pumping. After each circularly polarized pump laser pulse, an off-resonance linearly polarized probe beam measures the projection of 87Rb-spins along its axis in the dark. This transient signal is fitted to an exponentially damped sinusoid on top of an exponential decay to extract parameters of interest. With similar sensitivity and suppression of magnetic field compared to previous single-axis continuously pumped(CW) implementations, the pulsed comagnetometer exhibits additional advantages including dual-axis sensitivity, suppression of response to pump and probe beams' relative misalignment, and easy separation of various systematic effects. Thus it has the potential to reduce high 1/f noise that limited CW comagnetometers' performance. We discuss current limitations on the pulsed case and possible future improvements. |
Tuesday, May 31, 2022 12:00PM - 12:12PM |
C11.00006: Developments in Synchronous Spin-Exchange Optically Pumped NMR Gyroscopes Zaynab Yardim, Susan Sorensen, Thad G Walker In this study, we present a spin-exchange pumped NMR comagnetometer with 131Xe, 129 Xe, and Rb atoms that is continuously polarized transverse to a pulsed bias field. Previously, we showed that both Xe species can be simultaneously excited using Rb polarization modulation (PM) or bias pulse repetition rate modulation (PDM). Here, we present developments in our modulation scheme, using a hybrid PM-PDM modulation which is combination of two modulations introduced before. This scheme achieves µHz-scale rotation sensitivity and suppresses sub-Hz magnetic field fluctuations by a factor of 1500. We will describe systematic error studies with this system. |
Tuesday, May 31, 2022 12:12PM - 12:24PM |
C11.00007: Molecular sensing with single NV centers in diamond Erika W Janitz, John M Abendroth, Konstantin Herb, Tianqi Zhu, Laura Völker, Christian L Degen The field of nano-NMR aims to elucidate the composition and structure of matter using drastically reduced sensing volumes, ideally reaching the single- to few-molecule regime. One modality leverages the long-lived electronic spin of the nitrogen-vacancy (NV) center in diamond to detect the minute dipolar fields generated by nuclear spins in external molecules. In this talk, I will discuss diamond fabrication and surface treatments developed in our group to improve detection sensitivity while enabling highly generalizable molecular surface functionalization. Finally, I will discuss progress in using our NV-NMR platform to detect conformational changes in DNA molecules attached to the diamond interface. |
Tuesday, May 31, 2022 12:24PM - 12:36PM |
C11.00008: Long-Term Characterizations of an Absolute Magnetometer Based on EIT Isaac Fan, Yang Li, Daniel Rodriguez Castillo, Mario A Maldonado, Alex Toyryla, Irina Novikova, Eugeniy Mikhailov, Jamie McKelvy, Andrey B Matsko, John E Kitching Accurate magnetometers, such as proton magnetometers and Mz atomic magnetometers, play an important role in fields like navigation without GPS, ordnance detection, geomagnetic surveying, and fundamental physics. Such sensors lack the capability to yield vector information without external coil systems and calibration. Here, we present the development of a vector magnetometer based on electromagnetically induced transparency in a three-level system. This EIT magnetometer can produce scalar and vector information of a magnetic field simultaneously. We have measured the stability of such a magnetometer and find that the photon-shot noise limit is better than 20 pT/√Hz. Common systematics that affect the long-term stability and accuracy of the EIT magnetometer, like light shifts and pressure shifts, will be discussed. |
Tuesday, May 31, 2022 12:36PM - 12:48PM |
C11.00009: Determination of alkali-vapour–inert-gas diffusion coefficients using coherent transient emission from a density grating Alexander Pouliot, Gehrig M Carlse, Thomas Vacheresse, Hermina C Beica, A Kumarakrishnan We demonstrate a technique for the accurate measurement of diffusion coefficients for alkali vapor in an inert buffer gas. The measurement was performed by establishing a spatially periodic density grating in isotopically pure 87Rb vapor and observing the decaying coherent emission from the grating due to the diffusive motion of the vapor through N2 buffer gas. We obtain a diffusion coefficient of 0.245 ± 0.002 cm2/s at 50 ◦C and 564 Torr. Scaling to atmospheric pressure, we obtain D0 = 0.1819 ± 0.0024 cm2/s*. To the best of our knowledge, this represents the most accurate determination of the Rb-N2 diffusion coefficient to date. We review progress in extending these measurements to other buffer gases used for magnetometry. These measurements can be used to test calculations of inter-atomic potentials in these systems. |
Tuesday, May 31, 2022 12:48PM - 1:00PM |
C11.00010: Atom Arrangement with the Quantum Orchestration Platform Ramon Szmuk, Yoav Romach, Yonatan Cohen, Niv Drucker, Theo Laudat Neutral atoms arrays are a promising platform for quantum computation and simulation. While this platform has the potential to support a large number of high-quality qubits, there exist several roadblocks towards neutral atoms quantum devices that can lead to quantum advantage. One of the biggest challenges to realizing a scalable physical system with well-characterized qubits is the precise rearrangement of atoms on a 2D array, which requires unique control capabilities. |
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