Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session T8: Atomic Quantum Sensors |
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Sponsoring Units: GPMFC Chair: Ibrahim Sulai, University of Wisconsin Room: Franklin CD |
Friday, June 12, 2015 8:00AM - 8:12AM |
T8.00001: High-resolution imaging of a single atom for direct detection of atomic motion Jaime Wong-Campos, Kale Johnson, Brian Neyenhuis, Jonathan Mizrahi, Christopher Monroe We present the high-resolution detection of the motion of a single trapped 171Yb$+$ ion using high quality imaging optical elements. Light scattered from a trapped ion is collected in a lens system with 0.6 input numerical aperture and working distance of 11.5 mm.~ Near diffraction-limited performance from the imaging system is verified through the use of a Zernike expansion over the point spread function, giving a minimum spot size (FWHM) of 375nm.~ By means of a position sensitive detector, we measure a photon shot-noise limited sensitivity on the position of the trapped ion to be $\sim$ 5 nm/sqrt(Hz), bottoming out to an minimum absolute sensitivity of $\sim$ 1nm. We use this technique perform to directly measure the rf-induced micromotion of the trapped ion, and this technique can also be used to directly sense the thermal or driven secular motion of the trapped ion. [Preview Abstract] |
Friday, June 12, 2015 8:12AM - 8:24AM |
T8.00002: Atom-chip based quantum gravimetry with Bose-Einstein condensates Sven Abend, Matthias Gersemann, Holger Ahlers, Ernst M. Rasel, Martina Gebbe, Hauke Muentinga, Claus Laemmerzahl Today's generation of inertial sensitive atom interferometers typically operate with sources of laser cooled atoms and thus their performance is limited by velocity spread and finite-size effects that impose systematic uncertainties. Ultra-cold sources such as a BEC or even delta-kick cooled atomic ensembles with extremely narrow velocity dispersion are able to overcome these limitations and are crucial for obtaining high-fidelity beam splitters. Atom-chip technologies offer the possibility to generate a BEC and perform delta-kick cooling in a fast and reliable away. We show a combination of such an ensemble generated in a miniaturized atom-chip setup with the application of low-loss Bragg beam splitting to perform inertial sensitive measurements. A specialty of this setup is the retro-reflection of the beam splitting light field from the atom-chip itself, serving as inertial reference in vacuum. This allows for a compact realization of a quantum gravimeter determining the local gravitational acceleration to the scale of local variations limited by seismic noise. [Preview Abstract] |
Friday, June 12, 2015 8:24AM - 8:36AM |
T8.00003: Excess optical quantum noise in atomic sensors Irina Novikova, Eugeniy Mikhailov, Yanhong Xiao Enhanced nonlinear optical response of a coherent atomic medium is the basis for many atomic sensors, and their performance is ultimately limited by the quantum fluctuations of the optical read-out. Here we demonstrate that off-resonant interactions can significantly modify the quantum noise of the optical field, even when their effect on the mean signal is negligible. We illustrate this concept by using an atomic magnetometer based on the nonlinear Faraday effect: the rotation of the light polarization is mainly determined by the resonant light-induced spin alignment, which alone does not change the photon statistics of the optical probe. Yet, we found that the minimum noise of output polarization rotation measurements is above the expected shot noise limit. This excess quantum noise is due to off-resonant coupling and grows with atomic density. We also show that the detection scheme can be modified to reduce the measured quantum noise (even below the shot-noise limit) but only at the expense of the reduced rotational sensitivity. These results show the existence of previously unnoticed factors in fundamental limitations in atomic magnetometry and could have impacts in many other atom-light based precision measurements. [Preview Abstract] |
Friday, June 12, 2015 8:36AM - 8:48AM |
T8.00004: Spin-exchange narrowing in a nuclear magnetic transverse oscillator Anna Korver, Daniel Thrasher, Michael Bulatowicz, Thad Walker We demonstrate spin exchange narrowing in synchronously pumped Xe NMR. The Xe NMR is driven by spin exchange with Rb atoms whose polarization is square-wave modulated at the Xe NMR frequency. On resonance, the nuclei precess in phase with the Rb polarization. Off resonance, however, the spin-exchange fields from the Rb cause the Xe to develop a static orthogonal spin component. This induces broadening in the NMR line while also dramatically suppressing the phase shift between the precessing Rb and Xe polarizations. We can compensate for this effect by adding an oscillating magnetic field oriented along the optical pumping axis and 180 degrees out of phase with the Rb polarization. This narrows the NMR line width to approximately the T1 limit, and nearly restores the usual relationship between detuning and phase shift. These results suggest the possibility of using the alkali field with appropriate magnetic field feedback along the bias field direction to narrow the NMR linewidth below the usual T1 limit. [Preview Abstract] |
Friday, June 12, 2015 8:48AM - 9:00AM |
T8.00005: Sensitive force detection with a single trapped ion probe Ravid Shaniv, Roee Ozeri Trapped ions can be used as sensitive force probes. The ion motion in the trap is highly sensitive to forces acting on it. Thus by measuring the shift in the ion position or velocity it is possible to estimate the force acting on the ion. We used a quantum lock-in detection scheme on a narrow optical quadrupole transition to detect a force which oscillates at much lower frequency than the ion's trapping frequency. Our quantum lock-in detection measures the phase that is accumulated by the periodic Doppler shift due to the ion's motion. We achieve force detection sensitivity of the order of $10^{-21}N$. [Preview Abstract] |
Friday, June 12, 2015 9:00AM - 9:12AM |
T8.00006: Tunable atom chip potentials for confined atomic sensors James Stickney, Brian Kasch, Spencer Olson, Bethany Kroese, Jonathon Crow, Eric Imhof, Matthew Squires Devices that employ 1D potentials now have a tool with which precise potentials may be generated from a double layer atom chip. Based on this multi-wire method, we have designed, fabricated, and tested an atom chip capable of controlling the 1D potential using optimal and reduced power wire configurations. We have also shown the initial operation of a tunable atom chip by trapping atoms as cold as 2 $\mu$K in various potential configurations. We will present our current results on precision tuned atom chip potentials and its potential for precision measurements using atom interferometry. [Preview Abstract] |
Friday, June 12, 2015 9:12AM - 9:24AM |
T8.00007: Pulse Recycling and Weak Value Amplification for Precision Metrology Trent Graham, Courtney Byard, Paul Kwiat, Andrew Jordan Weak-value measurements have been shown to be useful for making precision optical measurements, owing to the huge amplification of tiny effects which is achievable with the technique (Hosten 2008, Dixon 2009, Egan 2012, Viza 2013). This amplification is especially helpful in the case where technical noise limits the resolution. However, if the intrinsic shot noise limits the resolution, weak-value measurements offer no advantage because the amplification is achieved via a postselection which discards most of the photons input into the measuring system. The reduction in photon number cancels the increase in signal from the amplification, and the resolution is not increased. To overcome this, we implement a method for recycling the discarded photons. We show that, for a given number of photons input to the system, recycling gives an improvement over the resolution of a conventional measurement. Our work with a simple double-pass recycling system demonstrated a 1.4x improvement over the standard shot-noise limit. We also present our work toward achieving a many-pass recycling system, for which we expect a five-fold improvement over the shot-noise limit. Such a weak-measurement recycling system could be combined with quantum states to further enhance the achievable resolution. [Preview Abstract] |
Friday, June 12, 2015 9:24AM - 9:36AM |
T8.00008: All optical absorptive pump-probe magnetometer Rui Zhang, Nobuko Fujikawa, Rahul Mhaskar We demonstrate the functioning of an all-optical pump-probe atomic magnetometer. Different from previous all-optical atomic magnetometers, in the new scheme, circularly polarized pump and probe beams resonantly address the two hyperfine ground states of the cesium D1 line. Amplitude modulated pump beam optically pumps atomic population into a dark state of the probe beam. The presence of a magnetic field (not parallel with light) mixes the dark state with the bright states through Larmor precession. Synchronization of the optical pumping frequency with the Larmor frequency generates a magnetic resonance, which can be detected through the probe light absorption. This variation of the Bell-Bloom [1] magnetometry scheme greatly reduces the side effects of the optical pumping on the magnetic resonance, such as the power broadening and the light-shift. The new scheme also provides free re-pumping from the probe light, thus enhancing the resonance. The magnetometer can reach close to photon shot-noise limited sensitivity using simply the absorption signal, which significantly simplifies the signal detection setup. Inside a less than 0.06 cm$^{3}$ Cs vapor cell, a sensitivity of 210 fT/rt-Hz is achieved. \\[4pt] [1] W. E. Bell and H. L. Bloom, Phys. Rev. Lett. \textbf{6}, 280 (1961) [Preview Abstract] |
Friday, June 12, 2015 9:36AM - 9:48AM |
T8.00009: Effect of One Axis Twist and Two Axes Twist Spin Squeezing on Collective State Atomic Interferometer and Clock Resham Sarkar, Renpeng Fang, May Kim, Selim Shahriar An ensemble of N independent, noninteracting 2-level atoms with states $|1\rangle$ and $|2\rangle$, interacting with a laser, can be represented as a Coherent State of spin, depicting a superposition of N+1 symmetric collective states. This model is also valid for 3-level atoms where the ground states $|1\rangle$ and $|2\rangle$ are mutually coupled via off-resonant Raman interaction through an intermediate excited state $|3\rangle$, upon adiabatic elimination thereof. We recently proposed a Collective State Atomic Interferometer (COSAIN) that splits, redirects and recombines such an ensemble to yield a signal that is a measurement of the ensemble state where all the atoms are simultaneously in state $|1\rangle$. The width of the COSAIN signal fringe scales as $1/\sqrt{N}$. This narrowing occurs due to the simultaneous interference of the N+1 arms of the COSAIN. A similar narrowing is also predicted for a Collective State Atomic Clock (COSAC) proposed by us. We will describe the effect of one-axis twist and two-axes twist spin squeezing on the behavior of the COSAIN and the COSAC in order to approach Heisenberg limited sensitivity. We will also discuss the prospect of implementing spin squeezed versions of these devices via the use of Rydberg assisted interaction among the atoms. [Preview Abstract] |
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