Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session G5: Gravity and Searches for Exotic Forces |
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Chair: Stephen Eckel, NIST Room: 310 |
Wednesday, June 7, 2017 8:00AM - 8:12AM |
G5.00001: Testing the universality of free fall with atoms in different quantum states Zhong-Kun Hu, Xiao-Chun Duan, Min-Kang Zhou, Lu-Shuai Cao We present tests of the universality of free fall by comparing the gravity acceleration of the $^{\mathrm{87}}$Rb atoms in m$_{\mathrm{F}}=$1 versus those in m$_{\mathrm{F}}=-$1, of which the corresponding spin orientations are opposite. A Mach-Zehnder-type atom interferometer is exploited to alternately measure the free fall acceleration of the atoms in these two magnetic sublevels, and the resultant Eötvös ratio is $\eta =$(0.2\textpm 1.2) × 10$^{\mathrm{-7}}$. This also gives an upper limit of 5.4 × 10$^{\mathrm{-6}}$ m$^{\mathrm{-2}}$ for a possible gradient field of the spacetime torsion. The interferometer using atoms in m$_{\mathrm{F}}=$\textpm 1 is highly sensitive to the magnetic field inhomogeneity. A double differential measurement method is developed to alleviate the inhomogeneity influence, of which the effectiveness is validated by a magnetic field modulating experiment. Other quantum tests of the universality of free fall with atoms in magnetic-insensitive states by employing larger enclosed spacetime area atom interferometer are discussed. \textbf{References } [1] Xiao-Chun Duan, Xiao-Bing Deng, Min-Kang Zhou, Ke Zhang, Wen-Jie Xu, Feng Xiong, Yao-Yao Xu, Cheng-Gang Shao, Jun Luo, and Zhong-Kun Hu*\textbf{, }Physical Review Letters, 117, 023001(2016); [2] Min-Kang Zhou, Le-Le Chen, Qin Luo, Ke Zhang, Xiao-Chun Duan, and Zhong-Kun Hu*, Physical Review A, ~93, 053615(2016). [Preview Abstract] |
Wednesday, June 7, 2017 8:12AM - 8:24AM |
G5.00002: Test of the equivalence principle using dual species atom interferometry Peter Asenbaum, Chris Overstreet, Tim Kovachy, Daniel Brown, Jason Hogan, Mark Kasevich Freely falling atoms are ideal test masses to probe gravitational interactions. Light-pulse interferometry allows one to study the motion of the atoms in respect to the laser beams, which act as rulers for the atomic position. We measure the differential acceleration of two atomic species simultaneously to test the weak equivalence principle. Long interferometer times and large momentum transfer techniques [1, 2] are crucial to improve the precision of this fundamental test. [1] T. Kovachy, P. Asenbaum, C. Overstreet, C. A. Donnelly, S. M. Dickerson, A. Sugarbaker, J. M. Hogan and M. A. Kasevich, Quantum superposition at the half-metre scale, Nature 528, 530--533 (2015) [2] P. Asenbaum, C. Overstreet, T. Kovachy, D.D. Brown, J. M. Hogan, and M. A. Kasevich, Phase shift in atom interferometry due to spacetime curvature, arXiv:1610.03832 (2016) [Preview Abstract] |
Wednesday, June 7, 2017 8:24AM - 8:36AM |
G5.00003: Testing sub-gravitational forces on atoms from a miniature, in-vacuum source mass Matthew Jaffe, Philipp Haslinger, Victoria Xu, Paul Hamilton, Amol Upadhye, Benjamin Elder, Justin Khoury, Holger Mueller In this talk, I will discuss our recent measurement of the gravitational attraction between cesium atoms in free fall and a centimeter-sized source mass using atom interferometry. Placing the source mass in vacuum provides sensitivity to a wide class of ``fifth force'' type interactions whose effects would otherwise be suppressed beyond detectability in regions of high matter density. Examples include so-called chameleon and symmetron fields, proposed as dark energy candidates. Our measurement tightens constraints on such theories by over two orders of magnitude. [Preview Abstract] |
Wednesday, June 7, 2017 8:36AM - 8:48AM |
G5.00004: Phase shift in atom interferometry due to spacetime curvature Chris Overstreet, Peter Asenbaum, Tim Kovachy, Daniel Brown, Jason Hogan, Mark Kasevich In previous matter wave interferometers, the interferometer arm separation was small enough that gravitational tidal forces across the arms can be neglected. Gravitationally-induced phase shifts in such experiments arise from the acceleration of the interfering particles with respect to the interferometer beam splitters and mirrors. By increasing the interferometer arm separation, we enter a new regime in which the arms experience resolvably different gravitational forces. Using a single-source gravity gradiometer, we measure a phase shift associated with the tidal forces induced by a nearby test mass. This is the first observation of spacetime curvature across the spatial extent of a single quantum system. [Preview Abstract] |
Wednesday, June 7, 2017 8:48AM - 9:00AM |
G5.00005: Development of a force sensor using atom interferometry to constrain theories on dark matter and dark energy Chandler Schlupf, Robert Niederriter, Eliot Bohr, Sami Khamis, Youna Park, Erik Szwed, Paul Hamilton Atom interferometry has been used in many precision measurements such as Newton's gravitational constant, the fine structure constant, and tests of the equivalence principle. We will perform atom interferometry in an optical lattice to measure the force felt by an atom due to a test mass in search of new forces suggested by dark matter and dark energy theories [1]. We will be developing a new apparatus using laser-cooled ytterbium to continuously measure this force by observing their Bloch oscillations [2]. Interfering atoms in an optical lattice allows continuous measurements in a small volume over a long period of time, enabling our device to be sensitive to time-varying forces while minimizing vibrational noise. We present the details of this experiment and the progress on it thus far. [1] P. Hamilton, M. Jaffe, P. Haslinger, Q. Simmons, H. Muller, and J. Khoury, ``Atom-interferometry Constraints on Dark Energy." Science, 349, 849-851 (2015). [2] B. Prasanna Venkatesh, M. Trupke, E. A. Hinds, and D. H. J. O'Dell, ``Atomic Bloch-Zener oscillations for sensitive force measurements in a cavity" Physical Review A, 80, 063834 (2009). [Preview Abstract] |
Wednesday, June 7, 2017 9:00AM - 9:12AM |
G5.00006: $^{3}$He-$^{129}$Xe co-magnetometer shifts from $^{87}$Rb decoupling sequences Mark Limes, Michael Romalis We are developing a $^{3}$He-$^{129}$Xe co-magnetometer for use as an NMR gyro and to search for spin-gravity interactions. Our $^{3}$He-$^{129}$Xe co-magnetometer has achieved a long-term bias drift of ~7.7 nHz at 7 h. For detection of $^{3}$He-$^{129}$Xe precession, we use a $^{87}$Rb magnetometer with fast magnetic field $\pi$ pulses and $\sigma_+/\sigma_-$ optical pumping, which results in suppression of spin-exchange relaxation. We use a Ramsey scheme that allows the noble gases to precess freely 'in-the-dark'. During this free precession we apply additional decoupling pulses to eliminate Rb-Xe back-polarization along all three axes. The presence of the decoupling magnetic fields causes additional frequency shifts which we can eliminate by rotating the decoupling fields. We are presently studying the absolute accuracy of the co-magnetometer by detecting Earth's rotation. We will describe the procedure to characterize remaining frequency shifts and our progress on mitigating them. [Preview Abstract] |
Wednesday, June 7, 2017 9:12AM - 9:24AM |
G5.00007: Search for long-range spin-mass forces Junyi Lee, Attaallah Almasi, Michael Romalis We report on the progress in the search for anomalous spin-mass interactions that can be mediated by light particles, for example axion-like particles, which are also potential candidates for dark matter. In this experiment, we measure energy shifts of spin polarized atoms in a $^3$He-K co-magnetometer as the positions of two nearby 200 kg unpolarized source masses are modulated. Bounds on possible anomalous spin-mass interactions can be extracted from correlations in these measurements. The sensitivity of the co-magnetometer should allow us to exceed for the first time the astrophysical limits on spin-dependent forces. Various systematic effects due to the motion and positions of the weights have also been studied and quantified. Supported by NSF PHY-1404325. [Preview Abstract] |
Wednesday, June 7, 2017 9:24AM - 9:36AM |
G5.00008: Synchronous Spin Exchange Comagnetometry Joshua Weber, Daniel Thrasher, Susan Sorensen, Anna Korver, Thad Walker Comagnetometry is achieved 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$\pi$n 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 as well as at a third frequency, which enables lock-in detection far from 1/f electronic noise. With this technique we approach photon-shot-noise-limited detection of longitudinal-relaxation-limited Xe linewidths of less than 10 mHz. Furthermore, the bias magnetic field is stabilized to the probe noise detection limit using the magnetic field fluctuations detected by one of the isotopes. With magnetic noise suppressed, the second isotope is used to detect non-magnetic interactions. [Preview Abstract] |
Wednesday, June 7, 2017 9:36AM - 9:48AM |
G5.00009: Searching for anomalous spin-spin interactions Attaallah Almasi, Himawan Winarto, Junyi Lee, Michael Romalis We report our progress and preliminary results of a newly designed experiment to search for anomalous spin-spin interactions using an electron spin source and a nuclear spin co-magnetometer. These interactions can be generated by pseudoscalar axion-like bosons or other light particles beyond the Standard Model. In our experiment, we look for an anomalous correlation between the signal of a Rb-Ne co-magnetometer and the orientation of a SmCo$_{5}$ magnet with an iron flux return. The spin source generates a net electron spin while cancelling most of the magnetic field, while the co-magnetometer cancels coupling to ordinary magnetic fields. Several layers of magnetic shielding provide additional suppression of ordinary magnetic field interactions. We collect the data as the direction of the spin source is rotated. We will present the data collected to date and discuss the limiting systematic effects. [Preview Abstract] |
Wednesday, June 7, 2017 9:48AM - 10:00AM |
G5.00010: Effect of atomic diffusion on spin noise spectroscopy with a tightly focused beam Vito Giovanni Lucivero, Nathaniel David McDonough, Nezih Dural, Michael Romalis Atomic diffusion can limit the sensitivity of atomic sensors and optical magnetometers. Here we introduce an analytical model for explaining the atomic diffusion component of the spin time-correlation function under different conditions of beam focusing and buffer gas pressure. For a tightly focused probe beam we find that the decay of the diffusion correlation function follows a power law rather than exponential, as it does in the collimated case. Counter-intuitively, this results in a narrowing of the spin-noise linewidth and significant increase in the noise peak amplitude. We are currently performing experimental measurements of the atomic diffusion effects in the spin noise spectra as a function of probe beams focus size down to 2 $\mu $m and as a function of the buffer gas pressure. We will present detailed comparison of theory and experiment and discuss implications of the atomic diffusion on sub-shot noise measurements in atomic sensors. [Preview Abstract] |
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