Bulletin of the American Physical Society
2006 APS March Meeting
Monday–Friday, March 13–17, 2006; Baltimore, MD
Session K1: Optical Frequency Clocks and Experimental Quantum Optics |
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Sponsoring Units: DAMOP Chair: David Weiss, Penn State University Room: Baltimore Convention Center Ballroom IV |
Tuesday, March 14, 2006 2:30PM - 3:06PM |
K1.00001: Trapped Ion Optical Clocks Invited Speaker: For the last fifty years, the international standard of time has been the caesium atomic clock, which is based on the 9.2 GHz microwave absorption in caesium-133 atoms. The recent Nobel Physics award to T W Haensch and J L Hall for their development of widespan femtosecond comb metrology has recognised the major role that femtosecond combs have made to the progress of optical frequency standards, and their use, going forward, as optical clocks. Such single trapped ion and cold atom optical clocks are now capable of challenging the best caesium fountain microwave clocks available. High accuracy frequency measurement of the single trapped ion optical frequency standards such as $^{199}$Hg$^{+}$ [1], $^{88}$Sr$^{+}$[2], and $^{171}$Yb$^{+}$ [3] by means of femtosecond combs referenced to the primary caesium fountain standard has now resulted in uncertainties at the 10$^{-15}$ level. These measurements are close to being limited by the caesium standard itself. Looking forward, it now becomes attractive to reverse the ``directionality'' of accuracy provision by referencing the comb to the optical frequency standard itself, and this concept has already been demonstrated [4]. The optical clock so formed can then deliver full accuracy of the optical standard to about a million comb modes across the visible and near infra-red, and, through the comb repetition rate frequency, to the microwave and rf regions. This presentation will review recent results and expected future capabilities of these optical clocks, particularly in respect of the single cold $^{88}$Sr$^{+}$ ion quadrupole and $^{171}$Yb$^{+}$ ion octupole clock transitions. [1] J C Bergquist et al 2005, submitted to Nature [2] H S Margolis et al. Science \textbf{306} 1355 (2004) [3] T Schneider et al Phys. Rev. Lett. \textbf{94} 230801 (2005) [4] S A Diddams et al. Science \textbf{293} 825 (2001) [Preview Abstract] |
Tuesday, March 14, 2006 3:06PM - 3:42PM |
K1.00002: Precision Spectroscopy of Hydrogen and Femtosecond Laser Frequency Combs Invited Speaker: A femtosecond frequency comb is a simple and compact tool that allows the phase coherent connection of the radio frequency domain (below ~100 GHz) with the optical domain (above 200~THz). It greatly simplified high precision optical frequency measurements and provides the long awaited clockwork mechanism for an all-optical atomic clock. We have used such a frequency comb to measure the absolute frequency of the 1S-2S two-photon transition in atomic hydrogen, i.e. comparing it with the Cs ground state hyperfine splitting. By comparing data taken in 2003 with earlier measurements in 1999 we can set an upper limit on the variation of the 1S-2S transition frequency of $(-29 \pm 57)$~Hz within 44 months. To derive limits on the drift rates of fundamental constant such as the fine structure constant, we combine these measurements with other optical frequency measurements in Hg$^+$ and in Yb$^+$ performed at NIST, Boulder/USA and at PTB, Braunschweig/Germany respectively. This combined method gives precise and separate restrictions for the fractional time variation of the fine structure constant and the Cs nuclear magnetic moment measured in Bohr magnetons. The latter is a measure of the drift rate of the strong interaction. We also report on efforts to convert the frequency comb technology to much shorter wavelength. Based on intra cavity high harmonic generation an XUV (up to 60~nm) frequency comb is generated with a repetition rate of more than 100~MHz useful for high resolution laser spectroscopy in this region. [Preview Abstract] |
Tuesday, March 14, 2006 3:42PM - 4:18PM |
K1.00003: Precision measurement meets ultrafast science Invited Speaker: Phase control of a single-frequency continuous-wave laser and the electric field of a mode-locked femtosecond laser has now reached the same level of precision, resulting in sub-optical-cycle phase coherence being preserved over macroscopic observation times exceeding seconds. The subsequent merge of CW laser-based precision optical-frequency metrology and ultra-wide-bandwidth optical frequency combs has produced remarkable and unexpected progress in precision measurement and ultrafast science. A phase-stabilized optical frequency comb spanning an entire optical octave ($>$ 300 THz) establishes millions of marks on an optical frequency ``ruler'' that are stable and accurate at the Hz level. Accurate phase connections among different parts of electromagnetic spectrum, including optical to radio frequency, are implemented. These capabilities have profoundly changed the optical frequency metrology, resulting in recent demonstrations of absolute optical frequency measurement, optical atomic clocks, and optical frequency synthesis. Combined with the use of ultracold atoms, optical spectroscopy and frequency metrology at the highest level of precision and resolution are being accomplished at this time. The parallel developments in the time domain applications have been equally revolutionary, with precise control of the pulse repetition rate and the carrier-envelope phase offset both reaching the sub-femtosecond regime. These developments have led to recent demonstrations of coherent synthesis of optical pulses from independent lasers, coherent control in nonlinear spectroscopy, coherent pulse addition without any optical gain, and coherent generation of frequency combs in the VUV and XUV spectral regions. Indeed, we now have the ability to perform completely arbitrary, optical, waveform synthesis, complement and rival the similar technologies developed in the radio frequency domain. With this unified approach on time and frequency domain controls, it is now possible to pursue simultaneously coherent control of quantum dynamics in the time domain and high precision measurements of global atomic and molecular structure in the frequency domain. These coherent light-based precision measurement capabilities may be extended to the XUV spectral region, where new possibilities and challenges lie for precise tests of fundamental physical principles. [Preview Abstract] |
Tuesday, March 14, 2006 4:18PM - 4:54PM |
K1.00004: The Hg/Al single-atom, optical clocks: on the path to inaccuracies below 10$^{-17}$ Invited Speaker: For the past fifty years, atomic standards based on the frequency of the cesium ground-state hyperfine transition have been the most accurate timepieces in the world. Recently, we reported a comparison between the cesium fountain standard NIST-F1, which has been evaluated with an inaccuracy of about 4 $\times $ 10$^{-16}$, and an optical frequency standard based on an ultraviolet transition in a single, laser-cooled mercury ion for which the fractional systematic frequency uncertainty was below 7.2 $\times $ 10$^{-17}$ [1]. We have also compared the frequency of the mercury ion optical clock to that of an optical standard based on the $^{1}$S$_{0} \quad \leftrightarrow \quad ^{3}$P$_{0}$ transition of $^{27}$Al$^{+}$ at 267 nm, which offers several attractive features as a single-ion optical clock. Its sharp natural linewidth, small electric quadrupole moment, and low quadratic Zeeman coefficient (0.7 Hz/B$^{2})$ allow for high stability and accuracy, but until recently, precision spectroscopy of Al$^{+}$ had not been possible, because it lacked an accessible, laser-cooling transition. However, with the development of quantum logic based spectroscopy [2, 3] a single aluminum ion can be efficiently probed. In our realization of this scheme, a single $^{9}$Be$^{+}$ ion is trapped together with the single Al ion in a linear Paul trap and is used to sympathetically cool the Al ion and to detect its internal state after the clock radiation is applied. We will report the latest results of the frequency comparison of the two optical standards and the implication these comparisons might have toward improved tests of the stability of Fundamental Constants. [1] W. H. Oskay \textit{et al.}, submitted for publication. [2] D. J. Wineland \textit{et al}., Proc. 6th Symp. on Freq. Standards and Metrology, 361 (2002). [3] P. O. Schmidt \textit{et al}., Science 309, 749 (2005). [Preview Abstract] |
Tuesday, March 14, 2006 4:54PM - 5:30PM |
K1.00005: Exploring the states of light: from photon counting to quantum information Invited Speaker: Forty years ago, the seminal papers of Roy Glauber have given a complete analysis of photon counting and light coherence, combining in a single theoretical framework a description of the granular and wave-like features of radiation. Glauber's theory has since then explained countless landmark experiments in quantum optics and has become an essential tool to understand the role played by photons in the physics of quantum information. We will describe a few experiments which illustrate the importance of Glauber's work in modern quantum optics. In addition, we will stress that complementary wave and particle behaviors are not restricted to light. They are also exhibited by atomic matter in Bose Einstein condensates. As we will see, Glauber's formalism of coherent states and particle counting has also found a remarkable testing ground in this new domain of research at the boundary between atomic and condensed matter physics. [Preview Abstract] |
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