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Rosenband T, Hume DB, Schmidt PO, Chou CW, Brusch A, Lorini L, Oskay WH, Drullinger RE, Fortier TM, Stalnaker JE, Diddams SA, Swann WC, Newbury NR, Itano WM, Wineland DJ, Bergquist JC. Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place. Science 2008; 319:1808-12. [PMID: 18323415 DOI: 10.1126/science.1154622] [Citation(s) in RCA: 1070] [Impact Index Per Article: 66.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Time has always had a special status in physics because of its fundamental role in specifying the regularities of nature and because of the extraordinary precision with which it can be measured. This precision enables tests of fundamental physics and cosmology, as well as practical applications such as satellite navigation. Recently, a regime of operation for atomic clocks based on optical transitions has become possible, promising even higher performance. We report the frequency ratio of two optical atomic clocks with a fractional uncertainty of 5.2 x 10(-17). The ratio of aluminum and mercury single-ion optical clock frequencies nuAl+/nuHg+ is 1.052871833148990438(55), where the uncertainty comprises a statistical measurement uncertainty of 4.3 x 10(-17), and systematic uncertainties of 1.9 x 10(-17) and 2.3 x 10(-17) in the mercury and aluminum frequency standards, respectively. Repeated measurements during the past year yield a preliminary constraint on the temporal variation of the fine-structure constant alpha of alpha/alpha = (-1.6+/-2.3) x 10(-17)/year.
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Affiliation(s)
- T Rosenband
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA.
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Fortier TM, Ashby N, Bergquist JC, Delaney MJ, Diddams SA, Heavner TP, Hollberg L, Itano WM, Jefferts SR, Kim K, Levi F, Lorini L, Oskay WH, Parker TE, Shirley J, Stalnaker JE. Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance. Phys Rev Lett 2007; 98:070801. [PMID: 17359009 DOI: 10.1103/physrevlett.98.070801] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Indexed: 05/14/2023]
Abstract
We report tests of local position invariance and the variation of fundamental constants from measurements of the frequency ratio of the 282-nm 199Hg+ optical clock transition to the ground state hyperfine splitting in 133Cs. Analysis of the frequency ratio of the two clocks, extending over 6 yr at NIST, is used to place a limit on its fractional variation of <5.8x10(-6) per change in normalized solar gravitational potential. The same frequency ratio is also used to obtain 20-fold improvement over previous limits on the fractional variation of the fine structure constant of |alpha/alpha|<1.3x10(-16) yr-1, assuming invariance of other fundamental constants. Comparisons of our results with those previously reported for the absolute optical frequency measurements in H and 171Yb+ vs other 133Cs standards yield a coupled constraint of -1.5x10(-15)<alpha/alpha<0.4x10(-15) yr-1 and -2.7x10(-15)<d/dtlnmicroCs/microB<8.6x10(-15) yr-1.
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Affiliation(s)
- T M Fortier
- P-23 Physics Division MS H803, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Oskay WH, Diddams SA, Donley EA, Fortier TM, Heavner TP, Hollberg L, Itano WM, Jefferts SR, Delaney MJ, Kim K, Levi F, Parker TE, Bergquist JC. Single-atom optical clock with high accuracy. Phys Rev Lett 2006; 97:020801. [PMID: 16907426 DOI: 10.1103/physrevlett.97.020801] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Indexed: 05/11/2023]
Abstract
For the past 50 years, atomic standards based on the frequency of the cesium ground-state hyperfine transition have been the most accurate time pieces in the world. We now report a comparison between the cesium fountain standard NIST-F1, which has been evaluated with an inaccuracy of about 4 x 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 x 10(-17). The absolute frequency of the transition was measured versus cesium to be 1,064,721,609,899,144.94 (97) Hz, with a statistically limited total fractional uncertainty of 9.1 x 10(-16) the most accurate absolute measurement of an optical frequency to date.
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Affiliation(s)
- W H Oskay
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
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Oskay WH, Itano WM, Bergquist JC. Measurement of the (199)Hg+ 5d9 6s2 (2)D(5/2) electric quadrupole moment and a constraint on the quadrupole shift. Phys Rev Lett 2005; 94:163001. [PMID: 15904220 DOI: 10.1103/physrevlett.94.163001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Indexed: 05/02/2023]
Abstract
The electric-quadrupole moment of the (199)Hg+ 5d9 6s2 (2)D(5/2) state is measured to be theta(D,5/2) = -2.29(8) x 10(-40) C m2. This value was determined by measuring the frequency of the (199)Hg+ 5d10 6s (2)S(1/2) --> 5d9 6s2 (2)D(5/2) optical clock transition for different applied electric-field gradients. An isolated, mechanically stable optical cavity provides a frequency reference for the measurement. We compare the results with theoretical calculations and discuss the implications for the accuracy of an atomic clock based upon this transition. We now expect that the frequency shift caused by the interaction of the quadrupole moment with stray electric-field gradients will not limit the accuracy of the Hg+ optical clock at the 10(-18) level.
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Affiliation(s)
- W H Oskay
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
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Bartels A, Diddams SA, Oates CW, Wilpers G, Bergquist JC, Oskay WH, Hollberg L. Femtosecond-laser-based synthesis of ultrastable microwave signals from optical frequency references. Opt Lett 2005; 30:667-669. [PMID: 15792011 DOI: 10.1364/ol.30.000667] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We use femtosecond laser frequency combs to convert optical frequency references to the microwave domain, where we demonstrate the synthesis of 10-GHz signals having a fractional frequency instability of < or =3.5 x 10(-15) at a 1-s averaging time, limited by the optical reference. The residual instability and phase noise of the femtosecond-laser-based frequency synthesizers are 6.5 x 10(-16) at 1 s and -98 dBc/Hz at a 1-Hz offset from the 10-GHz carrier, respectively. The timing jitter of the microwave signals is 3.3 fs.
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Affiliation(s)
- A Bartels
- Time and Frequency Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
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Bize S, Diddams SA, Tanaka U, Tanner CE, Oskay WH, Drullinger RE, Parker TE, Heavner TP, Jefferts SR, Hollberg L, Itano WM, Bergquist JC. Testing the stability of fundamental constants with the 199Hg+ single-ion optical clock. Phys Rev Lett 2003; 90:150802. [PMID: 12732024 DOI: 10.1103/physrevlett.90.150802] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2002] [Revised: 02/27/2003] [Indexed: 05/24/2023]
Abstract
Over a two-year duration, we have compared the frequency of the 199Hg+ 5d(10)6s (2)S(1/2)(F=0)<-->5d(9)6s(2) (2)D(5/2)(F=2) electric-quadrupole transition at 282 nm with the frequency of the ground-state hyperfine splitting in neutral 133Cs. These measurements show that any fractional time variation of the ratio nu(Cs)/nu(Hg) between the two frequencies is smaller than +/-7 x 10(-15) yr(-1) (1sigma uncertainty). According to recent atomic structure calculations, this sets an upper limit to a possible fractional time variation of g(Cs)(m(e)/m(p))alpha(6.0) at the same level.
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Affiliation(s)
- S Bize
- Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA.
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Abstract
We report the direct observation of quantum dynamical tunneling of atoms between separated momentum regions in phase space. We study how the tunneling oscillations are affected as a quantum symmetry is broken and as the initial atomic state is changed. We also provide evidence that the tunneling rate is greatly enhanced by the presence of chaos in the classical dynamics. This tunneling phenomenon represents a dramatic manifestation of underlying classical chaos in a quantum system.
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Affiliation(s)
- D A Steck
- Department of Physics, The University of Texas at Austin, Austin, TX 78712-1081, USA
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Zhong J, Diener RB, Steck DA, Oskay WH, Raizen MG, Plummer EW, Zhang Z, Niu Q. Shape of the quantum diffusion front. Phys Rev Lett 2001; 86:2485-2489. [PMID: 11289963 DOI: 10.1103/physrevlett.86.2485] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2000] [Indexed: 05/23/2023]
Abstract
We show that quantum diffusion has well-defined front shape. After an initial transient, the wave packet front (tails) is described by a stretched exponential P(x,t) = A(t)exp(-absolute value of [x/w](gamma)), with 1 < gamma < infinity, where w(t) is the spreading width which scales as w(t) approximately t(beta), with 0 < beta < or = 1. The two exponents satisfy the universal relation gamma = 1/(1-beta). We demonstrate these results through numerical work on one-dimensional quasiperiodic systems and the three-dimensional Anderson model of disorder. We provide an analytical derivation of these relations by using the memory function formalism of quantum dynamics. Furthermore, we present an application to experimental results for the quantum kicked rotor.
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Affiliation(s)
- J Zhong
- Department of Physics, University of Texas, Austin 78712, USA
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Steck DA, Milner V, Oskay WH, Raizen MG. Quantitative study of amplitude noise effects on dynamical localization. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:3461-3475. [PMID: 11088847 DOI: 10.1103/physreve.62.3461] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/1999] [Indexed: 05/23/2023]
Abstract
We study the motion of cold atoms in a pulsed standing wave of light, which constitutes an experimental realization of the quantum kicked rotor. This system exhibits dynamical localization, where quantum effects suppress classical momentum diffusion. As we introduce amplitude noise, the coherences that lead to localization are destroyed, resulting in restored diffusion. For high levels of noise, we find that the experiment is well described by a classical model, suggesting that classical behavior has been restored. We present a detailed experimental study of this noise-induced transition from quantum to classical behavior.
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Affiliation(s)
- DA Steck
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1081, USA
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Milner V, Steck DA, Oskay WH, Raizen MG. Recovery of classically chaotic behavior in a noise-driven quantum system. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:7223-7226. [PMID: 11088425 DOI: 10.1103/physreve.61.7223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/1999] [Indexed: 05/23/2023]
Abstract
The quantum kicked rotor is studied in a regime of high amplitude noise. A transition to diffusive behavior is observed as dynamical localization, characterized by suppressed diffusion and exponential momentum distributions, is completely destroyed by noise. With increasing noise amplitude, further transition to classical behavior is shown through an accurate quantitative analysis, which demonstrates that both the energy growth and the momentum distributions are reaching their classical limits. The importance of short-time correlations in the recovery of classically chaotic behavior is discussed.
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Affiliation(s)
- V Milner
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1081, USA
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