Bulletin of the American Physical Society
42nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 56, Number 5
Monday–Friday, June 13–17, 2011; Atlanta, Georgia
Session M2: Atomic Clocks |
Hide Abstracts |
Sponsoring Units: GPMFC Chair: Vladan Vuletic, Massachusetts Institute of Technology Room: A602 |
Thursday, June 16, 2011 8:00AM - 8:12AM |
M2.00001: Suppression of collisional shifts via strong inter-atomic interactions in a $^{87}$Sr optical lattice clock Michael Martin, Matthew Swallows, Michael Bishof, Yige Lin, Sebastian Blatt, Ana Maria Rey, Jun Ye Optical lattice clocks based on ensembles of neutral atoms have the potential to operate at the highest levels of stability due to the parallel interrogation of many atoms. However, the control of systematic shifts in these systems is correspondingly difficult due to the potential of collisional shifts. Clocks based on ultracold fermionic ensembles still exhibit these density-dependent shifts due to a loss of indistinguishability during the clock excitation process, limiting clock accuracy.\footnote{G. K. Campbell \textit{et al.,} Science, \textbf{324}(5925) pp. 360- 363, 2009.} By tightly confining samples of ultracold fermionic $^{87}$Sr atoms in a two-dimensional optical lattice, as opposed to the conventional one-dimensional geometry, we increase the collisional interaction energy to be the largest relevant energy scale, thus entering the strongly interacting regime of clock operation. We show both theoretically and experimentally that this increase in interaction energy results in a paradoxical decrease in the collisional shift, reducing this key systematic to the $10^{-17}$ level.\footnote{M~D.~Swallows \textit{et al.} Science, 10.1126/science.1196442, 2011} [Preview Abstract] |
Thursday, June 16, 2011 8:12AM - 8:24AM |
M2.00002: Toward a Portable Optical Atomic Clock in Neutral Silver (Ag) Carol Tanner The Ag metastable state 4d$^9$5s$^2$ $^2$D$_{5/2}$ has an estimated\footnote{R. H. Garstang, J. Res. Natl. Bur. Stand. Sect. A $\bf{68A}$, 61 (1964).} linewidth of 0.8 Hz. Proposed by Bender $\it{et al.}$,\footnote{P. L. Bender, J. L. Hall, R. H. Garstang, F. M. J. Pichanick, W. W. Smith, R. L. Barger, and J. B. West, Bull. Am. Phys. Soc. $\bf{21}$, 599 (1976).} the two-photon transition 4d$^{10}$5s $^2$S$_{1/2}$ $\rightarrow$ 4d$^9$5s$^{2}$ $^{2}$D$_{5/2}$ (661.2 nm=2x330.6 nm) has an oscillation frequency near 10$^{15}$ Hz and a quantum-noise instability limit of 1/10$^{18}$ with the potential to achieve femtosecond-timing resolution in one second. The velocity-dependent Doppler shift cancels out to first order, an advantage over one-photon optical clocks. No one optical clock can address all the goals of clock science, and comparisons between types operating at their expected limits can provide stringent tests of the fundamental constants. Ag is an excellent candidate for a portable optical clock and may make it possible to improve upon various real- time applications such as Global Positioning, distance ranging, and communications, as well as mapping gravity, testing general relativity, and measuring the time variation of fundamental constants. [Preview Abstract] |
Thursday, June 16, 2011 8:24AM - 8:36AM |
M2.00003: Precision calculation of blackbody radiation shifts for metrology at the 18$^{\textrm{th}}$ decimal place Marianna Safronova, Mikhail Kozlov, Charles W. Clark We developed a theoretical method within the framework of relativistic many-body theory to accurately treat correlation corrections in atoms with a few valence electrons. This method combines the all-order approach currently used in precision calculations of properties of monovalent atoms with the configuration-interaction approach that is applicable for many-electron systems. We have applied this method to accurately calculate the ground and excited state polarizabilities of divalent ions. The resulting polarizabilities are used to evaluate the blackbody radiation (BBR) shifts at 300K in the $ns^2 - nsnp~ ^3P_0$ clock transitions in Al$^+$, B$^+$, and In$^+$. Frequency-dependent corrections are also evaluated. We estimate that our calculation reduces the relative uncertainty due to BBR shift at 300K in Al$^+$ to $4\times10^{-19}$. We find the while the relative BBR shifts in B$^+$ and In$^+$ are larger than in Al$^+$, they are still anomalously small in comparison with BBR shifts in all other frequency standards. We estimate relative uncertainties due to BBR shifts in B$^+$ and In$^+$ to be at the $1\times10^{-18}$ level. [Preview Abstract] |
Thursday, June 16, 2011 8:36AM - 8:48AM |
M2.00004: Progress toward a single 229Th3+ ion nuclear optical clock Corey Campbell, Alexander Radnaev, Alex Kuzmich The extension of coherent state manipulation and precision laser spectroscopy and metrology from atomic to nuclear states would be a tremendous advance in fundamental physics research. The 7.6 eV isomeric transition in the 229Th nucleus is currently the sole candidate for such an extension. Experimental progress toward coherently exciting this transition in a laser-cooled triply charged 229Th ion is presented. [Preview Abstract] |
Thursday, June 16, 2011 8:48AM - 9:00AM |
M2.00005: Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca$^+$ U.I. Safronova, M.S. Safronova A systematic study of Ca$^+$ atomic properties is carried out using high-precision relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Energies, $E1$, $E2$, $E3$, matrix elements, transition rates, lifetimes, $A$ and $B$ hyperfine constants, $E1$, $E2$, and $E3$ ground state polarizabilities, scalar $E1$ polarizabilities of the $5s$, $6s$, $7s$, $8s$, $4p$, $5p$, $3d$, $4d$ states, and tensor polarizabilities of the $4p$, $5p$, $3d$, and $4d$ states are calculated. The uncertainties are evaluated for most of the values listed in this work. The blackbody radiation shift of the $4s - 3d_{5/2}$ clock transition in Ca$^+$ is calculated to be 0.381 (4)~Hz at room temperature, $T = 300 K$ improving its accuracy by a factor of 3. The quadratic Stark effect on hyperfine structure levels of $^{43}$Ca$^+$ ground state is investigated. These calculations provide recommended values critically evaluated for their accuracy for a number of Ca$^+$ atomic properties useful for a variety of applications. [Preview Abstract] |
Thursday, June 16, 2011 9:00AM - 9:12AM |
M2.00006: Cavity enhanced non-linear spectroscopy of ultra-narrow optical transitions Dominic Meiser, Michael J. Martin, Jun Ye, Murray J. Holland Optical atomic clocks are continuing to make rapid progress and are penetrating the 1 part in $10^{17}$ decade of fractional stability. A major bottleneck to further improvements of their stability is the linewidth of the clock lasers with which the atomic transitions are interrogated. The linewidth of these clock lasers is typically limited by thermal noise of the reference cavities which is technically challenging to overcome. Here we discuss an alternative laser stabilization scheme that is based on highly non-linear spectroscopy of ultra-narrow optical transitions in a cavity. We discuss the essential non-linear physics underlying this system and we show that laser linewidths in the 10 mHz range could be achieved with such a system using current experimental technology, an improvement of over an order of magnitude over the state-of-the-art. The fundamental limits of this approach are orders of magnitude below 1 mHz. [Preview Abstract] |
Thursday, June 16, 2011 9:12AM - 9:24AM |
M2.00007: Conditional Spin-Squeezing of a Large Ensemble via the Vacuum Rabi Splitting Zilong Chen, Justin G. Bohnet, Shannon R. Sankar, Jiayan (Phoenix) Dai, James K. Thompson We demonstrate that the collective vacuum Rabi splitting can be used to perform quantum nondemolition (QND) measurements of the psuedo-spin projection $J_z$ for the two-level clock states of nearly $10^6~^{87}$Rb atoms confined in a low finesse $F =710(10)$ optical cavity. The QND measurement is used to prepare a conditionally spin-squeezed state. We infer a 3.4(6)~dB improvement in quantum phase estimation relative to the standard quantum limit for a coherent spin state composed of uncorrelated atoms. The measurement is enhanced using a large ensemble and may lead to more precise atomic sensors and tests of fundamental physics. [Preview Abstract] |
Thursday, June 16, 2011 9:24AM - 9:36AM |
M2.00008: Optimized design of a polarization spectroscopy experiment to measure collective spin projection noise Enrique Montano, Pascal Mickelson, Poul Jessen We optimize the design of an experiment to measure the projection noise of the collective spin of an atomic ensemble. In our setup, a weak probe beam interacts with a trapped sample of cesium atoms, leading to Faraday rotation of the probe light proportional to the collective atomic magnetization. If the ensemble-light coupling is strong enough, polarimetry of the probe light provides a measurement of the magnetization with resolution better than the spin projection noise, at which point measurement back-action becomes significant and can be used for quantum control of the collective spin. Here, we discuss two aspects of the experiment: first, the ``mode matching'' between the incident probe beam and the light scattered by the atoms, and second, the trapping laser parameters required to produce suitable atom clouds. Our modeling indicates that the probe beam waist size and the aspect ratio of the atomic cloud are the most important parameters for good mode matching. [Preview Abstract] |
Thursday, June 16, 2011 9:36AM - 9:48AM |
M2.00009: Enhanced Spin Squeezing via Collective and Individual Atomic Control Leigh Norris, Collin Trail, Ivan Deutsch Spin squeezed states have generated considerable interest for their possible applications in metrology and quantum information processing. While recent years have witnessed great advances in producing spin squeezed states and understanding their properties, most spin squeezing research to date has focused on ensembles of qubit spins. We explore squeezed state production in an ensemble of spin-f alkali atoms. Collective interactions are achieved through coherent quantum feedback of a laser probe, interacting with the ensemble through the Faraday interaction. We study the enhancement of this process through further control of the atomic qudits. We control the internal atomic state both before and after the collective interaction. Initial preparation increases the collective squeezing parameter through enhancement of resolvable quantum fluctuations. Final control squeezes the individual atoms, further enhancing the total squeezing in a multiplicative manner. We show how decoherence is further suppressed in this system when compared to qubits. [Preview Abstract] |
Thursday, June 16, 2011 9:48AM - 10:00AM |
M2.00010: Quantum tomography of atomic spins via continuous measurement Carlos Riofrio, Ivan Deutsch, Aaron Smith, Brian Anderson, Poul Jessen Quantum tomography can be carried out by continuous weak measurement on an ensemble of identically prepared systems that are controlled so that an informationally complete measurement record is obtained (PRL 95, 030402 (2005)). In comparison to traditional tomography carried out by strong measurement on repeatedly prepared systems, this method has the advantage of being fast and accurate, as seen in experiments that reconstruct the density matrix of spins of ultracold atoms (PRL 95, 030402 (2005)). We show how our procedure can be extended to perform tomography on quantum states stored in the 16 dimensional ground-electronic hyperfine manifolds (F=3, F=4) of an ensemble of 133Cs atoms controlled by microwaves and radio-frequency magnetic fields and discuss our efforts, challenges, and results of the undergoing experimental implementation. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700