Test of Relativistic Gravitation with a Space-Borne Hydrogen Maser

Vessot, R. F. C.; Levine, M. W.; Mattison, E. M.; Blomberg, E.; Hoffman, T.; Nystrom, G.; Farrel, B. F.; Decher, R.; Eby, P. B.; Baugher, Charles R.; Watts, J. W.; Teuber, D.; Wills, F. D.

doi:10.1103/physrevlett.45.2081

Cited by 612 publications

(406 citation statements)

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“…This effect, known as the gravitational redshift, is the original test of the Einstein equivalence principle (EEP) [1] that underlies all of general relativity; its experimental verification [2][3][4][5][6] is fundamental to our confidence in the theory. Atom interferometer (AI) tests of the gravitational redshift [4,6] have a precision 10 000 times better than tests based on traditional clocks [3], but their status as redshift tests has been controversial [7]. Here, we show that the phase accumulated between two atomic wave packets in any interferometer equals the phase between any two clocks running at the atom's Compton frequency following the same paths, proving that atoms are clocks.…”

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confidence: 99%

Equivalence Principle and Gravitational Redshift

et al. 2011

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We investigate leading order deviations from general relativity that violate the Einstein equivalence principle in the gravitational standard model extension. We show that redshift experiments based on matter waves and clock comparisons are equivalent to one another. Consideration of torsion balance tests, along with matter wave, microwave, optical, and Mössbauer clock tests, yields comprehensive limits on spin-independent Einstein equivalence principle-violating standard model extension terms at the 10 −6 level.Gravity makes time flow differently in different places. This effect, known as the gravitational redshift, is the original test of the Einstein equivalence principle (EEP) [1] that underlies all of general relativity; its experimental verification [2-6] is fundamental to our confidence in the theory. Atom interferometer (AI) tests of the gravitational redshift [4,6] have a precision 10 000 times better than tests based on traditional clocks [3], but their status as redshift tests has been controversial [7]. Here, we show that the phase accumulated between two atomic wave packets in any interferometer equals the phase between any two clocks running at the atom's Compton frequency following the same paths, proving that atoms are clocks. For a quantitative comparison between different redshift tests, we use the standard model extension (SME) [8][9][10][11], which provides the most general way to describe potential low energy Lorentz symmetry-violating (thus EEP-violating) signatures of new physics at high energy scales. We show that all EEP tests are sensitive to the same five terms in the minimal gravitational SME [9][10][11] and, for the first time, comprehensively rule out EEP violation in redshift tests greater than a few parts per million for neutral matter.If two clocks are located at different points in spacetime, they can appear to tick at different frequencies, despite having the same proper frequency ω 0 in their local Lorentz frames. For clocks moving with nonrelativistic velocities v 1 and v 2 in a weak gravitational potentialThe first term is the gravitational redshift, originally measured [2] by Pound and Rebka in 1960, while the second term is the time dilation due to the clocks' relative motion. The redshift term can be isolated from the time dilation if the clocks' trajectories are known.The state of each clock can be described by a timevarying phase. If two clocks 1 and 2 are synchronized to have identical phase ϕ 0 = 0 at time t = 0, then theirMach-Zehnder clock or atom interferometer. Two otherwise freely falling clocks (or halves of an atomic wavepacket) receive momentum impulses that change their velocity by ±vr. The dashed lines indicate trajectories without gravity.specializing to a homogenous gravitational field so that φ 1 −φ 2 = g· r 12 , with r 12 being the clocks' distance vector and g the local acceleration of free fall. If the clocks are freely falling, then their motion is an extremum of their respective actions [12]Thus δϕ f is proportional to the difference S 1 − S 2 in the...

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confidence: 99%

Equivalence Principle and Gravitational Redshift

et al. 2011

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“…2) allows a relative uncertainty on the redshift determination given by the 10 −17 clock bias divided by the maximum value of (w G − w S ) / c 2 . For a distance of 50 AU this corresponds to a test with a relative uncertainty of 1.0 × 10 −9 , an improvement by about five orders of magnitude on the uncertainty obtained by the most sensitive experiment at present [4]. Additionally, the mission also provides the possibility of testing the velocity term in Eq.…”

Section: Test Of the Gravitational Redshift And Of Lorentz Invariancementioning

confidence: 99%

Quantum physics exploring gravity in the outer solar system: the SAGAS project

et al. 2008

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We summarise the scientific and technological aspects of the Search for Anomalous Gravitation using Atomic Sensors (SAGAS) project, submitted to ESA in June 2007 in response to the Cosmic Vision 2015-2025 call for proposals. The proposed mission aims at flying highly sensitive atomic sensors (optical clock, cold atom accelerometer, optical link) on a Solar System escape trajectory in the 2020 to 2030 time-frame. SAGAS has numerous science objectives in fundamental physics and Solar System science, for example numerous tests of general relativity and the exploration of the Kuiper belt. The combination of highly sensitive atomic sensors and of the laser link well adapted for large distances will allow measurements with unprecedented accuracy and on scales never reached before. We present the proposed mission in some detail, with particular emphasis on the science goals and associated measurements and technologies.

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“…The internal structure of the H maser is simpler than that of the Cesium atomic clock. Taking the values of the parameter |β H | of reference [19] as values of our parameter b, we can calculate the time difference using equation (53). It turns out that there is a difference of 0.007% with respect to Mashhoon's result.…”

Section: Estimative Of the Empirical Parametermentioning

confidence: 99%