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Université de Fribourg

Observation of gravitationally induced vertical striation of polarized ultracold neutrons by spin-echo spectroscopy

Afach, S. ; Ayres, N. J. ; Ban, G. ; Bison, Georg ; Bodek, K. ; Chowdhuri, Z. ; Daum, M. ; Fertl, M. ; Franke, B. ; Griffith, W. C. ; Grujić, Z. D. ; Harris, P. G. ; Heil, W. ; Hélaine, V. ; Kasprzak, Malgorzata ; Kermaidic, Y. ; Kirch, K. ; Knowles, Paul E. ; Koch, H.-C. ; Komposch, S. ; Kozela, A. ; Krempel, J. ; Lauss, B. ; Lefort, T. ; Lemière, Y. ; Mtchedlishvili, A. ; Musgrave, M. ; Naviliat-Cuncic, O. ; Pendlebury, J. M. ; Piegsa, F. M. ; Pignol, G. ; Plonka-Spehr, C. ; Prashanth, P. N. ; Quéméner, G. ; Rawlik, M. ; Rebreyend, D. ; Ries, D. ; Roccia, S. ; Rozpedzik, D. ; Schmidt-Wellenburg, P. ; Severijns, N. ; Thorne, J. A. ; Weis, Antoine ; Wursten, E. ; Wyszynski, G. ; Zejma, J. ; Zenner, J. ; Zsigmond, G.

In: Physical Review Letters, 2015, vol. 115, no. 16, p. 162502

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method...

Université de Fribourg

In situ calibration of magnetic field coils using free-induction decay of atomic alignment

Breschi, Evelina ; Grujić, Zoran D. ; Knowles, Paul E. ; Weis, Antoine

In: Applied Physics B, 2014, vol. 115, no. 1, p. 85–91

We propose a precision method for the in situ calibration of a three-axis coil system based on the free-induction decay of spin-aligned atoms. In addition, we present a simple and efficient method for measuring the three-vector components of a residual magnetic field.

Université de Fribourg

A high-sensitivity push-pull magnetometer

Breschi, Evelina ; Grujić, Zoran D. ; Knowles, Paul E. ; Weis, Antoine

In: Applied Physics Letters, 2014, vol. 104, no. 2, p. 023501

Université de Fribourg

Magneto-optical spectroscopy with polarization-modulated light

Breschi, Evelina ; Gruijć, Zoran D. ; Knowles, Paul E. ; Weis, Antoine

In: Physical Review A, 2013, vol. 88, no. 2, p. 022506

We present a combined theoretical and experimental study of magnetic resonance transitions induced by polarization-modulated light in cesium vapor exposed to a transverse magnetic field. Signals are obtained by phase-sensitive analysis of the light power traversing the vapor cell at six harmonics of the polarization modulation frequency. Resonances appear whenever the Larmor frequency matches an...

Université de Fribourg

A Bell-Bloom experiment with polarization-modulated light of arbitrary duty cycle

Fescenko, Ilja ; Knowles, Paul E. ; Weis, Antoine ; Breschi, Evelina

In: Optics Express, 2013, vol. 21, no. 13, p. 15121–15130

We report on a study of polarization-modulation experiments on the 4 → 3 hyperfine component of the D₁ transition in Cs vapor contained in a paraffin-coated cell. The laser beam’s polarization was switched between left- and right-circular polarization at a rate of 200 Hz. Variations of the transmitted light power were recorded while varying the amplitude of a transverse magnetic...

Université de Fribourg

CPT-pump-probe measurement of the Cs clock transition DC Stark shift

Robyr, Jean-Luc ; Knowles, Paul E. ; Weis, Antoine

In: Proceedings of the Annual IEEE International Frequency Control Symposium, 2011, p. 1-4

We report progress in measuring the third order electric polarizability of the Cs ground states using a Ramsey pump-probe experiment on coherent population trapped (CPT) atoms in a thermal atomic beam. We give a short description of the apparatus as well as the Fourier transform method used to monitor the phase and frequency of the Ramsey signal. Analysis of a typical data set is shown, proving...