Optical Atomic Clocks

Ludlow, Andrew D.; Boyd, Martin M.; Ye, Jun; Peik, Ekkehard; Schmidt, Piet O.

doi:10.48550/arxiv.1407.3493

Cited by 18 publications

(17 citation statements)

References 421 publications

(787 reference statements)

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“…Trapped single ions can be exploited to investigate the interaction between light and matter, and to construct optical clocks [1]. For these applications based on high precision spectroscopy a good understanding of the optical line shapes involved is indispensable.…”

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confidence: 99%

Determination of transition frequencies in a singleBa+138ion

et al. 2015

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Transition frequencies between low-lying energy levels in a single trapped 138 Ba + ion have been measured with laser spectroscopy referenced to an optical frequency comb. By extracting the frequencies of one-photon and two-photon components of the line shape using an eight-level optical Bloch model, we achieved 0.1 MHz accuracy for the 5d 2 D 3/2 -6p 2 P 1/2 and 6s 2 S 1/2 -5d 2 D 3/2 transition frequencies, and 0.2 MHz for the 6s 2 S 1/2 -6p 2 P 1/2 transition frequency.Trapped single ions can be exploited to investigate the interaction between light and matter, and to construct optical clocks [1]. For these applications based on high precision spectroscopy a good understanding of the optical line shapes involved is indispensable. We have employed an optical frequency comb [2] to measure transition frequencies in Ba + and a model based on optical Bloch equations to extract atomic parameters from fluorescence spectra. These are essential ingredients for high precision experiments, in particular for atomic parity violation measurements in single Ba + [3,4] and Ra + ions [5,6] in the search for new physics [7]. In this work the frequencies of transitions between three of the lowest fine structure levels in the 138 Ba + ion are addressed. These levels form a Λ-configuration as shown in Fig. 1. The level 6p 2 P 1/2 decays to the levels 6s 2 S 1/2 and 5d 2 D 3/2 with a branching ratio of about 3:1 [8]. We have measured the transition frequencies in a single 138 Ba + ion by driving the transitions 6s 2 S 1/2 -6p 2 P 1/2 and 5d 2 D 3/2 -6p 2 P 1/2 , employing an optical frequency comb as frequency reference. The dynamics of the population of the 2 P 1/2 level can be described by optical Bloch equations [9][10][11]. Coherent coupling between the 2 S 1/2 and 2 D 3/2 levels is observed when the two laser fields are detuned by the same amount from the respective atomic resonances. In this condition a two-photon process causes coherent population trapping, reducing the population of the 2 P 1/2 level [12]. For the measurements reported here a single Ba + ion is confined in a hyperbolic Paul trap (see Fig. 2). The trap is operated at frequency ω rf /2π = 5.44 MHz with a peak-to-peak rf voltage of typically V rf = 600 V. Additional electrodes provide a dc potential to compensate the effect of mechanical imperfections and stray fields, minimizing the micromotion of the ion in the trap. The trap is loaded by photoionization of 138 Ba atoms with laser light at wavelength 413.6 nm. The trap is mounted in a UHV chamber with residual gas pressure below 10 −10 mbar. Doppler cooling and detection of the Ba + ions is achieved with laser light at wavelengths λ 1 and λ 2 (see Fig 1). Laser light to drive the 6s 2 S 1/2 -6p 2 P 1/2 tran- * e.a.dijck@rug.nl † Present address: Department of Physics, Columbia University, New York, NY 10027 FIG. 1. Low-lying energy levels of the Ba+ ion. The wavelengths of the investigated transitions are given. FIG. 2. Schematic diagram of the hyperbolic Paul trap used for trapping Ba+ ions, consisting of ...

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Determination of transition frequencies in a singleBa+138ion

et al. 2015

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“…Here, as the reference value for the Allan deviation, we took σ y (1 s) ≈ 10 −16 characteristic of modern optical lattice clocks [95].…”

Section: Atomic Clocks and Cavitiesmentioning

confidence: 99%

Quantum sensor networks as exotic field telescopes for multi-messenger astronomy

Dailey,

Bradley,

Kimball

et al. 2020

Preprint

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Multi-messenger astronomy, the coordinated observation of different classes of signals originating from the same astrophysical event, provides a wealth of information about astrophysical processes with far-reaching implications [1][2][3][4]. So far, the focus of multi-messenger astronomy has been the search for conventional signals from known fundamental forces and standard model particles, like gravitational waves (GW). In addition to these known effects, quantum sensor networks [5] could be used to search for astrophysical signals predicted by beyond-standardmodel (BSM) theories [6]. Exotic bosonic fields are ubiquitous features of BSM theories and appear while seeking to understand the nature of dark matter and dark energy and solve the hierarchy and strong CP problems. We consider the case where high-energy astrophysical events could produce intense bursts of exotic low-mass fields (ELFs). We propose to expand the toolbox of multi-messenger astronomy to include networks of precision quantum sensors that by design are shielded from or insensitive to conventional standard-model physics signals. We estimate ELF signal amplitudes, delays, rates, and distances of GW sources to which global networks of atomic magnetometers [7,8] and atomic clocks [9, 10] could be sensitive. We find that, indeed, such precision quantum sensor networks can function as ELF telescopes to detect signals from sources generating ELF bursts of sufficient intensity. Thus ELFs, if they exist, could act as additional messengers for astrophysical events.

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“…To obtain a good time keeping device we need to ensure that the relative frequency error y(t) = (ω LO (t) − ω ref )/ω ref remains small. To this end an estimation of this error ŷ is ascertained at consecutive time intervals of a length T , and the local oscillator frequency is then adjusted by ( Optical atomic clocks are today's most precise measurement devices with an instability of 10 −18 after 7 hours of averaging [36]. Atomic clock accuracy reached a point where the main source of error contributing to σ(t) originates in the short time stability of the local oscillator [28].…”

Section: Theoretical Challenges Related To Atomic Clocksmentioning

confidence: 99%

An Analysis of the Stationary Operation of Atomic Clocks

Fraas

2016

Commun. Math. Phys.

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We develop an abstract model of atomic clocks that fully describes the dynamics of repeated synchronization between a classical oscillator and a quantum reference. We prove existence of a stationary state of the model and study its dependence on the control scheme, the interrogation time and the stability of the oscillator. For unbiased atomic clocks, we derive a fundamental bound on atomic clocks long time stability for a given local oscillator noise. In particular, we show that for a local oscillator noise with integrated frequency variance scaling as T α for short times T , the optimal clock time variance scales as F −(α+1)/(α+2) with respect to the quantum Fisher information, F , associated to the quantum reference.In an attempt to prove the bounds without the unbiasedness assumption, we derive a new Cramer-Rao type inequality.

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Optical Atomic Clocks

Cited by 18 publications

References 421 publications

Determination of transition frequencies in a singleBa+138ion

Determination of transition frequencies in a singleBa+138ion

Quantum sensor networks as exotic field telescopes for multi-messenger astronomy

An Analysis of the Stationary Operation of Atomic Clocks

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