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ABSTRACT: We report an experimental determination of the diamagnetic correction to the 9Be+ ground state hyperfine constant A. We measured A = −625 008 837.371(11) Hz at a magnetic field B of 4.4609 T. Comparison with previous results, obtained at lower values of B (0.68 T and 0.82 T), yields the diamagnetic shift coefficient k = 2.63(18)×10−11 T−2, where A(B)=A0(1+kB2). The zero-field hyperfine constant A0 is determined to be −625 008 837.044(12) Hz. The g-factor ratio gI′/gJ is determined to be 2.134 779 852 7(10)×10−4, which is equal to the value measured at lower B to within experimental error. Upper limits are placed on some other corrections to the Breit-Rabi formula. The measured value of k agrees with theoretical estimates.
Phys. Rev. A. 07/2011; 84(1).
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[show abstract]
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ABSTRACT: We report an experimental determination of the diamagnetic correction to the
$^9$Be$^+$ ground state hyperfine constant $A$. We measured $A$ =
$-625\,008\,837.371(11)$ Hz at a magnetic field $B$ of 4.4609 T. Comparison
with previous results, obtained at lower values of $B$ (0.68 T and 0.82 T),
yields the diamagnetic shift coefficient $k$ = $2.63(18) \times 10^{-11}$
T$^{-2}$, where $A(B)=A_0\times (1+k B^2)$. The zero-field hyperfine constant
$A_0$ is determined to be $-625\,008\,837.044(12)$ Hz. The $g$-factor ratio
${g_I}^\prime/g_J$ is determined to be $2.134\,779\,852\,7(10) \times 10^{-4}$,
which is equal to the value measured at lower $B$ to within experimental error.
Upper limits are placed on some other corrections to the Breit-Rabi formula.
The measured value of $k$ agrees with theoretical estimates.
06/2011;
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T Rosenband,
D B Hume,
P O Schmidt,
C W Chou,
A Brusch,
L Lorini,
W H Oskay,
R E Drullinger,
T M Fortier,
J E Stalnaker,
S A Diddams,
W C Swann,
N R Newbury, W M Itano,
D J Wineland,
J C Bergquist
[show abstract]
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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.
Science 04/2008; 319(5871):1808-12. · 31.20 Impact Factor
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J.E. Stalnaker,
S.A. Diddams,
T.M. Fortier,
K. Kim,
L. Hollberg,
J.C. Bergquist, W.M. Itano,
M.J. Delany,
L. Lorini,
W.H. Oskay,
T.P. Heavner,
S.R. Jefferts,
F. Levi,
T.E. Parker,
J. Shirley
[show abstract]
[hide abstract]
ABSTRACT: We report the technical aspects of the optical-to-microwave comparison for our recent measurements of the optical frequency
of the mercury single-ion frequency standard in terms of the SI second as realized by the NIST-F1 cesium fountain clock. Over
the course of six years, these measurements have resulted in a determination of the mercury single-ion frequency with a fractional
uncertainty of less than 7×10-16, making it the most accurately measured optical frequency to date. In this paper, we focus on the details of the comparison
techniques used in the experiment and discuss the uncertainties associated with the optical-to-microwave synthesis based on
a femtosecond laser frequency comb. We also present our most recent results in the context of the previous measurements of
the mercury single-ion frequency and arrive at a final determination of the mercury single-ion optical frequency: f(Hg+)=1 064 721 609 899 145.30(69) Hz.
Applied Physics B 10/2007; 89(2):167-176. · 2.19 Impact Factor
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R. J. Epstein,
S. Seidelin,
D. Leibfried,
J. H. Wesenberg,
J. J. Bollinger,
J. M. Amini,
R. B. Blakestad,
J. Britton,
J. P. Home, W. M. Itano,
J. D. Jost,
E. Knill,
C. Langer,
R. Ozeri,
N. Shiga,
D. J. Wineland
[show abstract]
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ABSTRACT: We have measured motional heating rates of trapped atomic ions, a factor that can influence multi-ion quantum logic gate fidelities. Two simplified techniques were developed for this purpose: one relies on Raman sideband detection implemented with a single laser source, while the second is even simpler and is based on time-resolved fluorescence detection during Doppler recooling. We applied these methods to determine heating rates in a microfrabricated surface-electrode trap made of gold on fused quartz, which traps ions 40 microns above its surface. Heating rates obtained from the two techniques were found to be in reasonable agreement. In addition, the trap gives rise to a heating rate of 300 plus or minus 30 per second for a motional frequency of 5.25 MHz, substantially below the trend observed in other traps.
08/2007;
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J. H. Wesenberg,
R. J. Epstein,
D. Leibfried,
R. B. Blakestad,
J. Britton,
J. P. Home, W. M. Itano,
J. D. Jost,
E. Knill,
C. Langer,
R. Ozeri,
S. Seidelin,
D. J. Wineland
[show abstract]
[hide abstract]
ABSTRACT: We investigate the temporal dynamics of Doppler cooling of an initially hot single trapped atom in the weak binding regime using a semiclassical approach. We develop an analytical model for the simplest case of a single vibrational mode for a harmonic trap, and show how this model allows us to estimate the initial energy of the trapped particle by observing the fluorescence rate during the cooling process. The experimental implementation of this temperature measurement provides a way to measure atom heating rates by observing the temperature rise in the absence of cooling. This method is technically relatively simple compared to conventional sideband detection methods, and the two methods are in reasonable agreement. We also discuss the effects of RF micromotion, relevant for a trapped atomic ion, and the effect of coupling between the vibrational modes on the cooling dynamics.
08/2007;
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T.M. Fortier,
N. Ashby,
J.C. Bergquist,
M.J. Delaney,
S.A. Diddams,
T.P. Heavner,
L. Hollberg, W.M. Itano,
S.R. Jefferts,
K. Kim,
W.H. Oskay,
T.E. Parker,
J. Shirley,
J.E. Stalnaker,
F. Levi,
L. Lorini
[show abstract]
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ABSTRACT: We report tests of local position invariance (LPI) and constancy of fundamental constants from measurements of the frequency ratio of the 282-nm <sup>199</sup>Hg<sup>+</sup> optical clock transition to the ground-state hyperfine splitting in <sup>133</sup>Cs. Analysis of the frequency ratio, extending over six years at NIST, is used to place a limit on the fractional variation of the two clocks of less than 5.8times10<sup>-6</sup> per change in normalized solar gravitational potential, and a limit on fractional variation of the fine structure constant at alpha dot/alpha < 1.3x10<sup>-16</sup> yr<sup>-1</sup>, assuming invariance of other fundamental constants. Comparison of our results with those previously reported for the absolute optical frequency measurements of coupled <sup>171</sup>Yb<sup>+</sup> versus other constraint <sup>133</sup>Cs standard yields a coupled constraint of -0.04times10<sup>-15</sup> < alpha dot/alpha < 0.46times10<sup>-15</sup> yr<sup>-1</sup> and <sup>-</sup>2.39times10<sup>-15</sup> < d/dt In mu<sub>Cs</sub>/mu<sub>B</sub> < 0.47times10<sup>-15</sup> yr<sup>-1</sup>.
Frequency Control Symposium, 2007 Joint with the 21st European Frequency and Time Forum. IEEE International; 07/2007
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T Rosenband,
P O Schmidt,
D B Hume, W M Itano,
T M Fortier,
J E Stalnaker,
K Kim,
S A Diddams,
J C J Koelemeij,
J C Bergquist,
D J Wineland
[show abstract]
[hide abstract]
ABSTRACT: We report, for the first time, laser spectroscopy of the 1S0-->3P0 clock transition in 27Al+. A single aluminum ion and a single beryllium ion are simultaneously confined in a linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling allows the beryllium ion to sympathetically cool the aluminum ion and also enables transfer of the aluminum's electronic state to the beryllium's hyperfine state, which can be measured with high fidelity. These techniques are applied to measure the clock transition frequency nu=1,121,015,393,207,851(6) Hz. They are also used to measure the lifetime of the metastable clock state tau=20.6+/-1.4 s, the ground state 1S0 g factor gS=-0.000,792,48(14), and the excited state 3P0 g factor gP=-0.001,976,86(21), in units of the Bohr magneton.
Physical Review Letters 06/2007; 98(22):220801. · 7.37 Impact Factor
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T M Fortier,
N Ashby,
J C Bergquist,
M J Delaney,
S A Diddams,
T P Heavner,
L Hollberg, W M Itano,
S R Jefferts,
K Kim,
F Levi,
L Lorini,
W H Oskay,
T E Parker,
J Shirley,
J E Stalnaker
[show abstract]
[hide abstract]
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.
Physical Review Letters 02/2007; 98(7):070801. · 7.37 Impact Factor
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[show abstract]
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ABSTRACT: Quantum mechanical effects which are manifested in measurements on trapped atomic ions are reviewed. Observation of these effects is facilitated by the long storage times of a fixed number of laser-cooled ions and by high detection sensitivities, primarily through the observation of scattered laser light. We discuss the observation of quantum jumps and the application of quantum jumps to measurement of atomic ion lifetimes and spectra, detection of antibunching of light, the quantum Zeno effect and quantum projection noise. Experiments which detect nonclassical features of fluorescent light from single or a few trapped ions are briefly reviewed. Finally, we discuss experiments which reveal quantum effects in the motion of trapped ions. We briefly describe possible future extensions for each of these topics.
Physica Scripta 01/2007; 1995(T59):286. · 1.20 Impact Factor
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D. Leibfried,
D. J. Wineland,
R. B. Blakestad,
J. J. Bollinger,
J. Britton,
J. Chiaverini,
R. J. Epstein, W. M. Itano,
J. D. Jost,
E. Knill,
C. Langer,
R. Ozeri,
R. Reichle,
S. Seidelin,
N. Shiga,
J. H. Wesenberg
[show abstract]
[hide abstract]
ABSTRACT: Recent theoretical advances have identified several computational algorithms that can be implemented utilizing quantum information
processing (QIP), which gives an exponential speedup over the corresponding (known) algorithms on conventional computers.
QIP makes use of the counter-intuitive properties of quantum mechanics, such as entanglement and the superposition principle.
Unfortunately it has so far been impossible to build a practical QIP system that outperforms conventional computers. Atomic
ions confined in an array of interconnected traps represent a potentially scalable approach to QIP. All basic requirements
have been experimentally demonstrated in one and two qubit experiments. The remaining task is to scale the system to many
qubits while minimizing and correcting errors in the system. While this requires extremely challenging technological improvements,
no fundamental roadblocks are currently foreseen.
Hyperfine Interactions 12/2006; 174(1):1-7. · 0.21 Impact Factor
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[show abstract]
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ABSTRACT: The differential polarizability, due to near-infrared light at 1126 nm, of the 27Al+ 1S0 -> 3P0 clock transition is measured to be 4\pi\epsilon_0 x (1.6 +/- 0.5) x 10^{-31} m^3. This measurement is combined with experimental oscillator strengths to extrapolate the differential static polarizability of the clock transition as 4\pi\epsilon_0 x (1.5 +/- 0.5) x 10^{-31} m^3. The resulting room temperature blackbody fractional frequency shift of -8(3) x 10^{-18} is the lowest known shift of all atomic transitions under consideration for optical frequency standards. A method is presented to estimate the differential static polarizability of an optical transition, from a differential light shift measurement.
12/2006;
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R. Ozeri, W. M. Itano,
R. B. Blakestad,
J. Britton,
J Chiaverini,
J. D. Jost,
C. Langer,
D. Leibfried,
R. Reichle,
S. Seidelin,
J. H. Wesenberg,
D. J. Wineland
[show abstract]
[hide abstract]
ABSTRACT: We analyze the error in trapped-ion, hyperfine qubit, quantum gates due to spontaneous scattering of photons from the gate laser beams. We investigate single-qubit rotations that are based on stimulated Raman transitions and two-qubit entangling phase-gates that are based on spin-dependent optical dipole forces. This error is compared between different ion species currently being investigated as possible quantum information carriers. For both gate types we show that with realistic laser powers the scattering error can be reduced to below current estimates of the fault-tolerance error threshold. Comment: 15 pages and 6 figures, updated, fixed typos
11/2006;
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[show abstract]
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ABSTRACT: The electrostatic modes of a cloud of ions confined in a Penning trap are discussed in the limit that the Debye length is small compared to the cloud dimensions and the cloud dimensions are small compared to the trap dimensions. Experimental measurements of some of these mode frequencies on plasmas of laser-cooled Be+ ions agree well with calculations. Observation of the modes provides a nondestructive method for obtaining information on the ion density and cloud shape. In addition, excitation of the modes by static field asymmetries may provide a practical limit to the density and number of charged particles that can be stored in a Penning trap.
Physica Scripta 08/2006; 46(3):282. · 1.20 Impact Factor
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W H Oskay,
S A Diddams,
E A Donley,
T M Fortier,
T P Heavner,
L Hollberg, W M Itano,
S R Jefferts,
M J Delaney,
K Kim,
F Levi,
T E Parker,
J C Bergquist
[show abstract]
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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.
Physical Review Letters 08/2006; 97(2):020801. · 7.37 Impact Factor
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J.E. Stalnaker,
S.A. Diddams,
K. Kim,
L. Hollberg,
E.A. Donley,
T.P. Heavner,
S.R. Jefferts,
F. Levi,
T.E. Parker,
J.C. Bergquist, W.M. Itano,
M.J. Jensen,
L. Lorini,
W.H. Oskay,
T.M. Fortier
[show abstract]
[hide abstract]
ABSTRACT: We report the technical details specific to our recent measurements of the optical frequency of the mercury single-ion frequency standard in terms of the SI second as realized by the NIST-F1 cesium fountain clock. In these measurements the total fractional uncertainty is ap 10<sup>-15</sup>, limited by the statistical measurement uncertainty. In this paper we will address the techniques employed for the optical-to-microwave comparison itself, which had an estimated fractional uncertainty of ap 3 times 10<sup>-16</sup>, limited by the stability of the electronics used for the comparison
International Frequency Control Symposium and Exposition, 2006 IEEE; 07/2006
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S Seidelin,
J Chiaverini,
R Reichle,
J J Bollinger,
D Leibfried,
J Britton,
J H Wesenberg,
R B Blakestad,
R J Epstein,
D B Hume, W M Itano,
J D Jost,
C Langer,
R Ozeri,
N Shiga,
D J Wineland
[show abstract]
[hide abstract]
ABSTRACT: Individual laser-cooled 24Mg+ ions are confined in a linear Paul trap with a novel geometry where gold electrodes are located in a single plane and the ions are trapped 40 microm above this plane. The relatively simple trap design and fabrication procedure are important for large-scale quantum information processing (QIP) using ions. Measured ion motional frequencies are compared to simulations. Measurements of ion recooling after cooling is temporarily suspended yield a heating rate of approximately 5 motional quanta per millisecond for a trap frequency of 2.83 MHz, sufficiently low to be useful for QIP.
Physical Review Letters 07/2006; 96(25):253003. · 7.37 Impact Factor
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D Leibfried,
E Knill,
S Seidelin,
J Britton,
R B Blakestad,
J Chiaverini,
D B Hume, W M Itano,
J D Jost,
C Langer,
R Ozeri,
R Reichle,
D J Wineland
[show abstract]
[hide abstract]
ABSTRACT: Among the classes of highly entangled states of multiple quantum systems, the so-called 'Schrödinger cat' states are particularly useful. Cat states are equal superpositions of two maximally different quantum states. They are a fundamental resource in fault-tolerant quantum computing and quantum communication, where they can enable protocols such as open-destination teleportation and secret sharing. They play a role in fundamental tests of quantum mechanics and enable improved signal-to-noise ratios in interferometry. Cat states are very sensitive to decoherence, and as a result their preparation is challenging and can serve as a demonstration of good quantum control. Here we report the creation of cat states of up to six atomic qubits. Each qubit's state space is defined by two hyperfine ground states of a beryllium ion; the cat state corresponds to an entangled equal superposition of all the atoms in one hyperfine state and all atoms in the other hyperfine state. In our experiments, the cat states are prepared in a three-step process, irrespective of the number of entangled atoms. Together with entangled states of a different class created in Innsbruck, this work represents the current state-of-the-art for large entangled states in any qubit system.
Nature 01/2006; 438(7068):639-42. · 36.28 Impact Factor
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D. J. Wineland,
D. Leibfried,
M D Barrett,
A. Ben-Kish,
J.C. Bergquist,
R. B. Blakestad,
J. J. Bollinger,
J. Britton,
J Chiaverini,
B DeMarco, [......],
E. Knill,
J. Koelemeij,
C. Langer,
W. Oskay,
R. Ozeri,
R. Reichle,
T. Rosenband,
T Schaetz,
P O Schmidt,
S. Seidelin
[show abstract]
[hide abstract]
ABSTRACT: We briefly discuss recent experiments on quantum information processing using trapped ions at NIST. A central theme of this work has been to increase our capabilities in terms of quantum computing protocols, but we have also applied the same concepts to improved metrology, particularly in the area of frequency standards and atomic clocks. Such work may eventually shed light on more fundamental issues, such as the quantum measurement problem.
09/2005;
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C Langer,
R Ozeri,
J D Jost,
J Chiaverini,
B Demarco,
A Ben-Kish,
R B Blakestad,
J Britton,
D B Hume, W M Itano,
D Leibfried,
R Reichle,
T Rosenband,
T Schaetz,
P O Schmidt,
D J Wineland
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate experimentally a robust quantum memory using a magnetic-field-independent hyperfine transition in 9Be+ atomic ion qubits at a magnetic field B approximately = 0.01194 T. We observe that the single physical qubit memory coherence time is greater than 10 s, an improvement of approximately 5 orders of magnitude from previous experiments with 9Be+. We also observe long coherence times of decoherence-free subspace logical qubits comprising two entangled physical qubits and discuss the merits of each type of qubit.
Physical Review Letters 09/2005; 95(6):060502. · 7.37 Impact Factor
