Optical atomic clocks

Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

doi:10.48550/arxiv.1401.2378

Cited by 9 publications

(16 citation statements)

References 220 publications

(372 reference statements)

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“…After ACES, there are plans to put an optical clock on the ISS as part of the Space Optical Clock (SOC) project. The best optical clocks on Earth have already reached accuracies of ∆f /f ∼ 10 −18 over an integration period of 25000 sec [25,26], and significant progress is being made towards building optical clocks that are mobile, more compact and more reliable.…”

Section: Measuring Ppn Parameters In Earth's Exterior Fieldmentioning

confidence: 99%

Testing scalar-tensor theories and parametrized post-Newtonian parameters in Earth orbit

et al. 2014

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We compute the PPN parameters γ and β for general scalar-tensor theories in the Einstein frame, which we compare to the existing PPN formulation in the Jordan frame for alternative theories of gravity. This computation is important for scalar-tensor theories that are expressed in the Einstein frame, such as chameleon and symmetron theories, which can incorporate hiding mechanisms that predict environment-dependent PPN parameters. We introduce a general formalism for scalar-tensor theories and constrain it using the limit on γ given by the Cassini experiment. In particular we discuss massive Brans-Dicke scalar fields for extended sources. Next, using a recently proposed Earth satellite experiment, in which atomic clocks are used for spacecraft tracking, we compute the observable perturbations in the redshift induced by PPN parameters deviating from their general relativistic values. Our estimates suggest that |γ − 1| ∼ |β − 1| ∼ 10 −6 may be detectable by a satellite that carries a clock with fractional frequency uncertainty ∆f /f ∼ 10 −16 in an eccentric orbit around the Earth. Such space experiments are within reach of existing atomic clock technology. We discuss further the requirements necessary for such a mission to detect deviations from Einstein relativity.

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Section: Measuring Ppn Parameters In Earth's Exterior Fieldmentioning

confidence: 99%

Testing scalar-tensor theories and parametrized post-Newtonian parameters in Earth orbit

et al. 2014

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“…While for 87 Sr with its mHz-linewidth, decay is no major limitation at the moment, alternative approaches with e.g. calcium atoms have already reached this limit [9].…”

Section: Introductionmentioning

confidence: 99%

Protected subspace Ramsey spectroscopy

et al. 2014

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We study a modified Ramsey spectroscopy technique employing slowly decaying states for quantum metrology applications using dense ensembles. While closely positioned atoms exhibit superradiant collective decay and dipole-dipole induced frequency shifts, recent results [Ostermann, Ritsch and Genes, Phys. Rev. Lett. \textbf{111}, 123601 (2013)] suggest the possibility to suppress such detrimental effects and achieve an even better scaling of the frequency sensitivity with interrogation time than for noninteracting particles. Here we present an in-depth analysis of this 'protected subspace Ramsey technique' using improved analytical modeling and numerical simulations including larger 3D samples. Surprisingly we find that using sub-radiant states of $N$ particles to encode the atomic coherence yields a scaling of the optimal sensitivity better than $1/\sqrt{N}$. Applied to ultracold atoms in 3D optical lattices we predict a precision beyond the single atom linewidth.Comment: 9 pages, 7 figure

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“…Ground clocks can thus be combined with existing instrumentations (GPS, InSAR, gravimeters) to track underground mass redistribution through its effects on the geopotential. Portable optical clocks have already been developed (Poli et al 2014), and could monitor changes in the geopotential of the Earth across fault lines, in areas with active volcanoes, and for surveying.…”

Section: Discussionmentioning

confidence: 99%

“…However, optical clocks have the potential for higher stability because they utilize atomic transitions with resonance line-widths typically 10 5 narrower than microwave transitions. Since the development of the femtosecond laser frequency comb, optical clocks have been improving extremely rapidly (Poli et al 2014). Today's best clocks are optical.…”

Section: Overview Of Atomic Clocksmentioning

confidence: 99%

“…where τ is the integration period (Hinkley et al 2013;Bloom et al 2014;Nicholson et al 2015), and are likely to continue to improve dramatically within the next decade (Poli et al 2014). A transportable optical clock that monitors and compensates for environmental effects (temperature, pressure, electric and magnetic fields) and fits within two cubic meters has recently been built (Poli et al 2014).…”

Section: Overview Of Atomic Clocksmentioning

confidence: 99%

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Ground-based optical atomic clocks as a tool to monitor vertical surface motion

Bondarescu

Schärer

Hetényi

et al. 2015

Geophysical Journal International

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According to general relativity, a clock experiencing a shift in the gravitational potential ∆U will measure a frequency change given by ∆f /f ≈ ∆U/c 2 . The best clocks are optical clocks. After about 7 hours of integration they reach stabilities of ∆f /f ∼ 10 −18 , and can be used to detect changes in the gravitational potential that correspond to vertical displacements of the centimetre level. At this level of performance, ground-based atomic clock networks emerge as a tool that is complementary to existing technology for monitoring a wide range of geophysical processes by directly measuring changes in the gravitational potential. Vertical changes of the clock's position due to magmatic, post-seismic or tidal deformations can result in measurable variations in the clock tick rate. We illustrate the geopotential change arising due to an inflating magma chamber using the Mogi model, and apply it to the Etna volcano. Its effect on an observer on the Earth's surface can be divided into two different terms: one purely due to uplift (free-air gradient) and one due to the redistribution of matter. Thus, with the centimetre-level precision of current clocks it is already possible to monitor volcanoes. The matter redistribution term is estimated to be 3 orders of magnitude smaller than the uplift term. Additionally, clocks can be compared over distances of thousands of kilometres over short periods of time, which improves our ability to monitor periodic effects with long-wavelength like the solid Earth tide.

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Optical atomic clocks

Cited by 9 publications

References 220 publications

Testing scalar-tensor theories and parametrized post-Newtonian parameters in Earth orbit

Testing scalar-tensor theories and parametrized post-Newtonian parameters in Earth orbit

Protected subspace Ramsey spectroscopy

Ground-based optical atomic clocks as a tool to monitor vertical surface motion

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