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Université de Fribourg

Searching for axion stars and $Q$-balls with a terrestrial magnetometer network

Kimball, D. F. Jackson ; Budker, D. ; Eby, J. ; Pospelov, M. ; Pustelny, Szymon ; Scholtes, Theo ; Stadnik, Y. V. ; Weis, Antoine ; Wickenbrock, A.

In: Physical Review D, 2018, vol. 97, no. 4, p. 043002

Light (pseudo-)scalar fields are promising candidates to be the dark matter in the Universe. Under certain initial conditions in the early Universe and/or with certain types of self-interactions, they can form compact dark-matter objects such as axion stars or Q-balls. Direct encounters with such objects can be searched for by using a global network of atomic magnetometers. It is shown that...

Université de Fribourg

An arbitrary-function light power controller

Grujić, Zoran D. ; Piller, Jari ; Weis, Antoine

In: Review of Scientific Instruments, 2018, vol. 89, no. 2, p. 025114

We describe the design, applications, and performance of a simple light power controller. The device is built on a fiber-coupled electro-optic modulator with an active electronic feedback. It can be used to actively stabilize laser power or to impress an arbitrary waveform onto the power. The bandwidth of the device is ∼70 kHz.

Université de Fribourg

Quantitative study of optical pumping in the presence of spin-exchange relaxation

Shi, Yongqi ; Scholtes, Theo ; Grujić, Zoran D. ; Lebedev, Victor ; Dolgovskiy, Vladimir ; Weis, Antoine

In: Physical Review A, 2018, vol. 97, no. 1, p. 013419

We have performed quantitative measurements of the variation of the on-resonance absorption coefficients κ0 of the four hyperfine components of the Cs D1 transition as a function of laser power P, for pumping with linearly and with circularly polarized light. Sublevel populations derived from rate equations assuming isotropic population relaxation (at a rate γ1) yield algebraic κ0(P)...

Université de Fribourg

Study of ³He Rabi nutations by optically-pumped cesium magnetometers

Koch, Hans-Christian ; Bison, Georg ; Grujiæ, Zoran Dragan ; Heil, Werner ; Kasprzak, Malgorzata ; Knowles, Paul ; Kraft, Andreas ; Pazgalev, Anatoly ; Schnabel, Allard ; Voigt, Jens ; Weis, Antoine

In: The European Physical Journal D, 2017, vol. 71, no. 10, p. 262

We describe a method for recording the Rabi nutation of nuclear spin polarized ³He by optically pumped cesium magnetometers. The measurement is performed by detecting the time-dependent magnetic field produced by the 3He magnetization. The observed signals are compared to theoretical models and the results are used to precisely trace the evolution of the magnetization. This procedure...

Université de Fribourg

Search for axionlike dark matter through nuclear spin precession in electric and magnetic fields

Abel, C. ; Ayres, N.?J. ; Ban, G. ; Bison, G. ; Bodek, K. ; Bondar, V. ; Daum, M. ; Fairbairn, M. ; Flambaum, V.?V. ; Geltenbort, P. ; Green, K. ; Griffith, W.?C. ; Grinten, M. van der ; Grujiæ, Z.?D. ; Harris, P.?G. ; Hild, N. ; Iaydjiev, P. ; Ivanov, S.?N. ; Kasprzak, M. ; Kermaidic, Y. ; Kirch, K. ; Koch, H.-C. ; Komposch, S. ; Koss, P.?A. ; Kozela, A. ; Krempel, J. ; Lauss, B. ; Lefort, T. ; Lemi?re, Y. ; Marsh, D.?J.?E. ; Mohanmurthy, P. ; Mtchedlishvili, A. ; Musgrave, M. ; Piegsa, F.?M. ; Pignol, G. ; Rawlik, M. ; Rebreyend, D. ; Ries, D. ; Roccia, S. ; Rozpêdzik, D. ; Schmidt-Wellenburg, P. ; Severijns, N. ; Shiers, D. ; Stadnik, Y.?V. ; Weis, Antoine ; Wursten, E. ; Zejma, J. ; Zsigmond, G.

In: Physical Review X, 2017, vol. 7, no. 4, p. 041034

We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of the spin-precession frequencies of stored ultracold neutrons and 199Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range 10−24≤ma≤10−17 eV. Our null result...

Université de Fribourg

Comment on: Magnetic field measurements in Rb vapor by splitting Hanle resonances under the presence of a perpendicular scanning magnetic field

Weis, Antoine ; Shi, Yongqi ; Grujić, Zoran D.

In: The European Physical Journal D, 2017, vol. 71, no. 4, p. 80

In a recent article in this journal Grewal and Pattabiraman reported on the splitting of ground state Hanle resonances (recorded with linearly polarized light) by a transverse field. They claimed a “linearly proportional” dependence on the transverse field strength and supported this observation with results from numerical simulations. In this comment we argue that the splitting occurs...

Université de Fribourg

Orientational dependence of optically detected magnetic resonance signals in laser-driven atomic magnetometers

Colombo, Simone ; Dolgovskiy, Vladimir ; Scholtes, Theo ; Grujić, Zoran D. ; Lebedev, Victor ; Weis, Antoine

In: Applied Physics B, 2017, vol. 123, no. 1, p. 35

We have investigated the dependence of lock-in-demodulated Mx-magnetometer signals on the orientation of the static magnetic field B0 of interest. Magnetic resonance spectra for 2400 discrete orientations of B0 covering a 4π solid angle have been recorded by a PC-controlled steering and data acquisition system. Off-line fits by previously derived lineshape functions allow us to extract the...

Université de Fribourg

Roadmap on quantum optical systems

Dumke, Rainer ; Lu, Zehuang ; Close, John ; Robins, Nick ; Weis, Antoine ; Mukherjee, Manas ; Birkl, Gerhard ; Hufnagel, Christoph ; Amico, Luigi ; Boshier, Malcolm G ; Dieckmann, Kai ; Li, Wenhui ; Killian, Thomas C

In: Journal of Optics, 2016, vol. 18, no. 9, p. 093001

This roadmap bundles fast developing topics in experimental optical quantum sciences, addressing current challenges as well as potential advances in future research. We have focused on three main areas: quantum assisted high precision measurements, quantum information/simulation, and quantum gases. Quantum assisted high precision measurements are discussed in the first three sections, which ...

Université de Fribourg

A magnetic source imaging camera

Dolgovskiy, Vladimir ; Fescenko, Ilja ; Sekiguchi, N. ; Colombo, Simone ; Lebedev, Victor ; Zhang, J. ; Weis, Antoine

In: Applied Physics Letters, 2016, vol. 109, no. 2, p. 023505

We describe a magnetic source imaging camera (MSIC) allowing a direct dynamic visualization of the two-dimensional spatial distribution of the individual components Bx(x,y), By(x,y) and Bz(x,y) of a magnetic field. The field patterns allow—in principle— a reconstruction of the distribution of sources that produce the field B→ by inverse problem analysis. We compare experimentally...