A high-performance magnetic shield with large length-to-diameter ratio

Dickerson, Susannah; Hogan, Jason; Johnson, David M.; Kovachy, Timothy; Sugarbaker, Alex; Chiow, Sheng‐wey; Kasevich, Mark A.

doi:10.1063/1.4720943

Cited by 32 publications

(25 citation statements)

References 20 publications

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“…Unlike alkalis, the bosonic isotopes of Yb have no magnetic moment in the ground state. Eliminating the need for magnetic shielding makes Yb a promising atom for precision measurements [8]. The large number of stable isotopes, both fermionic and bosonic [9], allow a variety of properties to be modified between experiments, further enhancing the appeal of Yb for precision interferometry.…”

Section: Introductionmentioning

confidence: 99%

Advances in precision contrast interferometry with Yb Bose-Einstein condensates

2014

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Using a three-path contrast interferometer (CI) geometry and laser-pulse diffraction gratings, we create the first matter-wave interferometer with ytterbium (Yb) atoms. We present advances in contrast interferometry relevant to high-precision measurements. By comparing to a traditional atom interferometer, we demonstrate the immunity of the CI to vibrations for long interaction times (> 20 ms). We characterize and demonstrate control over the two largest systematic effects for a high-precision measurement of the fine structure constant via photon recoil with our interferometer: diffraction phases and atomic interactions. Diffraction phases are an important systematic for most interferometers using large-momentum transfer beam splitters; atomic interactions are a key concern for any BEC interferometer. Finally, we consider the prospects for a future sub-part per billion photon recoil measurement using a Yb CI.

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Section: Introductionmentioning

confidence: 99%

Advances in precision contrast interferometry with Yb Bose-Einstein condensates

2014

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“…They are then coherently launched with an optical lattice [13], which transfers 2386 photon momenta with a peak acceleration of 75 g. They enter the interferometer region, a 10 cm diameter, 8.7 m long aluminum vacuum tube. A solenoid wound around the tube provides a bias magnetic field, and three layers of magnetic shielding suppress the environmental field to < 1 mG [14].…”

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confidence: 99%

Multiaxis Inertial Sensing with Long-Time Point Source Atom Interferometry

et al. 2013

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We show that light-pulse atom interferometry with atomic point sources and spatially resolved detection enables multi-axis (two rotation, one acceleration) precision inertial sensing at long interrogation times. Using this method, we demonstrate a light-pulse atom interferometer for 87 Rb with 1.4 cm peak wavepacket separation and a duration of 2 T = 2.3 s. The inferred acceleration sensitivity of each shot is 6.7 × 10 −12 g, which improves on previous limits by more than two orders of magnitude. We also measure the Earth's rotation rate with a precision of 200 nrad/s.PACS numbers: 03.75. Dg, 37.25.+k, 06.30.Gv Light-pulse atom interferometry enables precision tests of gravity [1][2][3] and electrodynamics [4] as well as practical applications in inertial navigation, geodesy, and timekeeping. Phase shifts for light-pulse atom interferometers demonstrate sensitivity to the initial velocity distribution of the atom source, often resulting in inhomogeneous dephasing that washes out fringe contrast [5]. In this Letter, we show that use of spatially resolved imaging in combination with an initially spatially localized atomic source allows direct characterization of these phase shifts. We refer to this technique as point source interferometry (PSI).The contrast loss associated with such inhomogeneous dephasing is not fundamental, but is a consequence of atom detection protocols that average over velocitydependent phase shifts. With PSI we establish a correlation between velocity and position and use spatiallyresolved detection to form an image of the ensemble that reveals its velocity-dependent phase structure. A simple way to realize this correlation is through ballistic expansion of the ensemble. In the limit that the ensemble size at detection is much larger than its initial size, each atom's position is approximately proportional to its initial velocity. Consequently, any initial velocitydependent phase shift results in a spatial variation of the interferometer phase, yielding a position-dependent population difference between the two output ports of the interferometer.An important example of velocity sensitivity is due to rotation of the interferometer laser beams [3,6]. Rotation at a rate Ω leads to a phase shift (Table I, term 2) that depends on (v x , v y ), the initial transverse velocity of the atom. In a rotating frame, this effect may be interpreted as a Coriolis acceleration. PSI also allows observation of longitudinal velocity-dependent phase shifts in asymmetric atom interferometers [7] (e.g., Table I, term 3).To demonstrate PSI, we induce a velocity-dependent phase shift in a 87 Rb Raman light-pulse atom interferometer. We launch cold atoms from the bottom of a 10-meter tall vacuum enclosure (Fig. 1a) and apply a threepulse accelerometer sequence (π/2−π−π/2) [8]. The first pulse serves as an atom beamsplitter, coherently driving the atoms into a superposition of states |F = 1; p and |F = 2; p + k eff with momentum difference k eff = 2 k. Over the subsequent T = 1.15 s interrogation interval, the two...

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“…13 The corresponding longitudinal damping is more than 100 times lower, as expected from the large length-todiameter ratio. 12 Owing to the cancellation of the field's divergence in vacuum, the longitudinal field must be homogeneous if the transverse gradients are nulled and it can therefore be adjusted by a simple solenoid. Finally, we note that the change of slope observed in all directions around 1 Hz is characteristic of the crossover between effective shielding by the permalloy sheets at low frequencies and by the aluminum pipe above this threshold.…”

Section: A Dynamical Shielding Factormentioning

confidence: 99%

A scalable high-performance magnetic shield for very long baseline atom interferometry

Wodey

Tell

Rasel

et al. 2020

Review of Scientific Instruments

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We report on the design, construction, and characterization of a 10 m-long high-performance magnetic shield for Very Long Baseline Atom Interferometry (VLBAI). We achieve residual fields below 4 nT and longitudinal inhomogeneities below 2.5 nT/m over 8 m along the longitudinal direction. Our modular design can be extended to longer baselines without compromising the shielding performance. Such a setup constrains biases associated with magnetic field gradients to the sub-pm/s 2 level in atomic matterwave accelerometry with rubidium atoms and paves the way towards tests of the universality of free fall with atomic test masses beyond the 10 −13 level.

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A high-performance magnetic shield with large length-to-diameter ratio

Cited by 32 publications

References 20 publications

Advances in precision contrast interferometry with Yb Bose-Einstein condensates

Advances in precision contrast interferometry with Yb Bose-Einstein condensates

Multiaxis Inertial Sensing with Long-Time Point Source Atom Interferometry

A scalable high-performance magnetic shield for very long baseline atom interferometry

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