Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock

Affolderbach, C.; Du, Guanxiang; Bandi, Thejesh; Horsley, Andrew; Treutlein, Philipp; Mileti, G.

doi:10.1109/tim.2015.2444261

Cited by 35 publications

(28 citation statements)

References 33 publications

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“…The result is a compact device with approximately three times lower volume compared to a simple cylindrical geometry. 15 The field homogeneity of such cavities was previously studied experimentally 17 and theoretically, 18 where the loop-gap approach was found to perform on a par with the standard cylindrical geometry. The quality of field orientation can be evaluated by the Field Orientation Factor (FOF), 13 obtained by numerical simulations as FOF % 0.9, over the whole cell volume.…”

Section: à13mentioning

confidence: 99%

Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Affolderbach

Moreno

Иванов

et al. 2018

Applied Physics Letters

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Additive manufacturing (AM) of passive microwave components is of high interest for the costeffective and rapid prototyping or manufacture of devices with complex geometries. Here, we present an experimental study on the properties of recently demonstrated microwave resonator cavities manufactured by AM, in view of their applications to high-performance compact atomic clocks. The microwave cavities employ a loop-gap geometry using six electrodes. The critical electrode structures were manufactured monolithically using two different approaches: Stereolithography (SLA) of a polymer followed by metal coating and Selective Laser Melting (SLM) of aluminum. The tested microwave cavities show the desired TE 011 -like resonant mode at the Rb clock frequency of %6.835 GHz, with a microwave magnetic field highly parallel to the quantization axis across the vapor cell. When operated in an atomic clock setup, the measured atomic Rabi oscillations are comparable to those observed for conventionally manufactured cavities and indicate a good uniformity of the field amplitude across the vapor cell. Employing a time-domain Ramsey scheme on one of the SLA cavities, high-contrast (34%) Ramsey fringes are observed for the Rb clock transition, along with a narrow (166 Hz linewidth) central fringe. The measured clock stability of 2.2 Â 10 À13 s À1/2 up to the integration time of 30 s is comparable to the current state-of-the-art stabilities of compact vapor-cell clocks based on conventional microwave cavities and thus demonstrates the feasibil-ity of the approach.Compact microwave atomic clocks 1 based on alkali vapor cells 2,3 are widely employed as stable frequency references in numerous applications, ranging from telecommunication networks 4 to onboard clocks in satellite navigation systems. 5,6 In such atomic clocks, the frequency of a quartz local oscillator is stabilized to an inherently stable microwave transition in an alkali atom vapor held in a vapor cell. This greatly suppresses the quartz's fractional frequency instabilities to the 10 À12 to <10 À14 range (timing accuracies of 0.1 ls to <1 ns, respectively) over timescales up to one day. During the last decade, thanks to the employment of laser optical pumping, important advances were made in vapor-cell Rb atomic clocks based on the double-resonance (DR) scheme, using both the continuouswave (CW) 7 and the pulsed optical pumping (POP) interrogation (Ramsey scheme), 8,9 where the pulsed Ramsey scheme is of particular interest for highly compact and high-performance Rb cell clocks. In all types of DR atomic clocks, the microwave resonator cavity is a critical component for applying the microwave field to the atoms in a well-controlled geometry. In view of practical applications, this microwave cavity should be small and light-weight and feature simple and fast assembly. In DR atomic clocks, such cavities are generally manufactured by conventional subtractive precision machining of metals, often followed by time-consuming assembly steps requiring precise positioning or ali...

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Section: à13mentioning

confidence: 99%

Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Affolderbach

Moreno

Иванов

et al. 2018

Applied Physics Letters

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“…The latter are referred as "driving fields" and are defined as function of the standing magnetic field provided at a given point r inside the volume of the vapor cell [12]:…”

Section: ) Field Uniformitymentioning

confidence: 99%

Design of atomic clock cavity based on a loop-gap geometry and modified boundary conditions

Иванов

Affolderbach

Mileti

et al. 2017

Int. J. Microw. Wireless Technol.

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In this study, we investigate a concept that can be used to improve the magnetic field homogeneity in a microwave cavity applied in a novel, high-performance atomic frequency standard. We show that by modifying the boundary conditions in the case of a loop-gap geometry, a good improvement of the field homogeneity can be obtained. Such a design demonstrates high potential to improve the frequency stability; it is compact and hence suitable for a future generation of compact, highprecision frequency standards based on vapor cells and a pulsed optical pumping (POP) regime (POP atomic clocks).Keywords: Passive components and circuits, RFID and sensors I . I N T R O D U C T I O NSynchronization and time keeping have a crucial role in the modern world with ever-increasing number of applications, which require frequency stabilities that are beyond the limits of currently employed quartz oscillators: telecommunication applications, smart grid power networks, global positioning systems, high-frequency trading to name a few. Traditionally, frequency standards based on vapor cells and double resonance are recognized as excellent solutions when highfrequency stability needs to be combined with compactness [1]. Their performance is roughly between the large-scale laboratory clocks [2] or commercial Cs clocks [3] and the quartz oscillators widely employed in end-user products [4]. This type of clocks have been steadily improved in the last decades resulting in commercial products that today reach fractional frequency instability of few 10 215 (in terms of Allan deviation), over time scales (integration time) t ≥ 10 4 s [5]. Recently, a new generation of vapor-cell clocks based on pulsed optical pumping (POP) achieved state-of-the-art long-term stability [5] in laboratory conditions. Generally, the microwave cavity has an important role in the operation of vapor-cell clocks and has been in the focus of serious study. For the case of the pulsed clock, the magnetic field homogeneity plays a central role in limiting the performance [6], and hence the cavity needs to be engineered accordingly. In the following study, we address this challenge and investigate a possible solution based on a combination of a loop-gap structure and modified boundary conditions (BCs). Such a cavity design is found to be capable of improving the magnetic field homogeneity while still being very compact.The organization of the paper is the following: In Section II, we include a brief description of the main principle behind the operation of the clock in the context of POP. In Section III, we discuss how the cavity design is linked to the performance of the clock. Next we introduce figures of merit related to the efficiency and the homogeneity and discuss general design guidelines assuming the canonical case of a cylindrical cavity. The loop-gap geometry is introduced in Section IV. In Section V, the modified BCs are discussed in relation to cavity applications. In Section VI, we take into account the whole complexity of the problem and propose a suitable...

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“…was measured in an Rb clock cavity via adiabatic rapid passage [46], a MW magnetic field distribution was imaged with Rabi oscillations inside a microfabricated Rb vapour cell [38,39]. The technique here provides an alternate, direct means for accurate measurement of magnetic field strength inside a cell in gas-type atomic clocks, where traditional measurements are unavailable because of the presence of the vapour cell [33,41].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, atom-based microwave (MW) measurement has also inspired great interest because of its potential ability to link the MW quantities with SI units. As a result, relying on various physical principles, many atom-based MW sensors have been developed [1], such as the MW power standard [16][17][18][19], MW electrometry [20][21][22][23][24][25][26][27][28][29][30][31][32], MW electric/magnetic field imaging [22,[33][34][35][36][37][38][39][40], and MW magnetometers [41,42]. As compared to traditional measurement, atom-based measurement is intrinsically calibrated where field strength is translated into Rabi frequency W via well-known atomic constants.…”

Section: Introductionmentioning

confidence: 99%

“…The agreement of the experimental results and theoretical calculations proves our technique is simple and effective. We note that the measurement of MW magnetic fields inside the cavity-cell physical system plays an important role in the development of high-performance, vapour cell-based atomic clocks [38,39,46]. There have already been different approaches to this application.…”

Section: Introductionmentioning

confidence: 99%

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Rabi resonance in Cs atoms and its application to microwave magnetic field measurement

et al. 2018

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We have recently presented a technique for measuring unknown microwave (MW) fields based on Rabi resonances induced by the interaction of atoms with a phase-modulated MW field. The singlepeak feature of the measurement model makes the technique a valuable tool for simple and fast field measurement. Here we demonstrated a detailed investigation of Rabi resonance of Cs atoms inside a vapour cell. For illustration, we used the Rabi resonance-based field detection technique to determine the field strength inside an X-band cavity for applied power in the range of −21 to 20 dBm. The difference between the practical measurement and the simulation was approximately about 3% for an applied power of 20 dBm, and a higher accuracy could be expected for a larger power input.

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Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock

Cited by 35 publications

References 33 publications

Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Design of atomic clock cavity based on a loop-gap geometry and modified boundary conditions

Rabi resonance in Cs atoms and its application to microwave magnetic field measurement

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