Project

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A push-pull magnetometer with an internal microwave frequency reference

English title A push-pull magnetometer with an internal microwave frequency reference
Applicant Breschi Evelina
Number 131926
Funding scheme Ambizione
Research institution Département de Physique Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Other disciplines of Physics
Start/End 01.01.2011 - 28.02.2014
Approved amount 484'746.00
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Keywords (9)

laser spectroscopy; quantum sensors; atomic clocks; Atomic physics; atomic magnetometers; alkali atoms; vapor cells; coherent population trapping; push-pull optical pumping

Lay Summary (English)

Lead
Lay summary
This project will investigate a branch of atomic magnetometry which has been poorly investigated to date. The proposed atomic magnetometer measures the magnetic field by a phase-sensitive comparison of the atomic Larmor precession frequency with the frequency of a specific electromagnetic radiation interacting with the atoms. For precise and sensitive applications the external frequency should be referenced to a frequency standard such as an atomic clock. We propose to study a variant of the coherent population trapping (CPT) effect, the so-called push-pull optical pumping, recently proposed by the Happer group of Princenton University. The enhancement of the resonance contrast in the case of push-pull excitation of hyperfine coherences (clock application) has already been proven, but its use in magnetometry has not yet been explored. We want to demonstrate that with this approach we can efficiently access both magnetic field sensitive and magnetic field insensitive resonances in order to develop a device consisting of a sensitive atomic magnetometer containing its own intrinsic time-reference. The project is organized in three phases: the realization of the experimental apparatus, the investigation of the relevant features of the light-atom interaction and finally the characterization of the self-referenced magnetometer.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
A high-sensitivity push-pull magnetometer
Evelina Breschi, Zoran D. Grujic, Paul Knowles, Antoine Weis (2014), A high-sensitivity push-pull magnetometer, in Applied physics Letters, 104, 023501.
State-state solutions for atomic multipoles moments in an arbitrarily oriented static magnetic field
Giuseppe Bevilacqua, Evelina Breschi, Antoine Weis (2014), State-state solutions for atomic multipoles moments in an arbitrarily oriented static magnetic field, in Physical Reivew A, 89, 033406.
A Bell-Bloom experiment with polarization-modulated light of arbitrary duty cycle
Ilja Fescenko, Paul Knowles, Antoine Weis, Evelina Breschi (2013), A Bell-Bloom experiment with polarization-modulated light of arbitrary duty cycle, in Optics Express, 21(13), 15121-15130.
In situ calibration of magnetic field coils using free-induction decay of atomic alignment
Breschi Evelina, Grujić Zoran D., Weis A. (2013), In situ calibration of magnetic field coils using free-induction decay of atomic alignment, in Applied Physics B: Lasers and Optics, 1-7.
Magneto-optical spectroscopy with polarization-modulated light
Breschi Evelina, Gruijć Z. D., Knowles Paul E., Weis Antoine (2013), Magneto-optical spectroscopy with polarization-modulated light, in Physical Review A - Atomic, Molecular, and Optical Physics, 88(2), 022506.
Ground state Hanle effect based on atomic alignment
Breschi Evelina, Weis Antoine (2012), Ground state Hanle effect based on atomic alignment, in Physical Review A, 86, 053427.
Push-pull optical pumping on the Cs D1-transition
Evelina Breschi, Antoine Weis (2012), Push-pull optical pumping on the Cs D1-transition, in EFTF proceedings, 300.

Collaboration

Group / person Country
Types of collaboration
FEMTO France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
INRIM Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Dipartimento di Fisica, Università di Siena Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Internal seminar (Observatoire SYRTHE) Individual talk Magneto-optical spectroscopy and magnetometry with polarization-modulated laser light, 14.11.2013 Paris, France Breschi Evelina;
Internal seminar (Université de Paris Nord) Individual talk Magneto-optical spectroscopy and magnetometry with polarization-modulated laser light, 13.11.2013 Paris , France Breschi Evelina;
6th International Symposium on modern problems of laser physics (MPLP) Talk given at a conference A push-pull magnetometer 25.08.2013 Novosibirsk, Russia Breschi Evelina;
Joint European Time and Frequency standards Talk given at a conference A push-pull magnetometer 21.07.2013 Prague, Czech Republic Breschi Evelina;
Ecole Thématique Magnétométrie 2012 Individual talk no title 22.10.2012 Branville, Normandie, FRANCE , France Breschi Evelina;
International conference of atomic physics (ICAP) Poster Magneto-optical resonances with polarization modulated light. 23.07.2012 Paris, France Breschi Evelina;
Annual meeting SPS 2012 Poster Ground state Hanle effect based on atomic alignment: theory and experiments 21.06.2012 Zürich, Switzerland Breschi Evelina;
European Time and Frequency Forum (EFTF) 2012 Poster Push-pull optical pumping on the Cs D1-transition 24.04.2012 Goteborg, Sweden Breschi Evelina;
the European Group on Atomic System (EGAS 43) Poster Laser spectroscopy of optical transitions in Rb microfabricated cells 28.07.2011 Fribourg, Switzerland Breschi Evelina;


Communication with the public

Communication Title Media Place Year
Print (books, brochures, leaflets) EPL PosterPrize at the SPS Annual Meeting 2012 Communications de la SPS Western Switzerland German-speaking Switzerland 2012
New media (web, blogs, podcasts, news feeds etc.) http://physics.unifr.ch/fr/page/479/ Western Switzerland 2011
Talks/events/exhibitions Physics Day Western Switzerland 2011

Awards

Title Year
EPL Poster Prize at SPS 2012

Associated projects

Number Title Start Funding scheme
140421 Optical magnetometry for a new neutron EDM experiment 01.04.2012 Project funding
130480 Optical magnetometry for a new neutron EDM experiment 01.04.2010 Project funding
126499 A measurement of the hyperfine Stark shift in cesium using pump-probe CPT spectroscopy 01.10.2009 Project funding

Abstract

Although known since the 1950s, atomic magnetometry based on paramagnetic atoms polarized by resonant light has received a new boost in the past decade due to the implementation of low-cost solid state diode lasers. Atomic magnetometers, and their close relative the atomic clock, are quantum sensors whose production in terms of sensitive, small, portable, and scalable quantum devices will become a key industrial development for the near future. Besides research laboratory applications in fundamental science, such devices will have a large range of practical uses, ranging from geology, archaeology to medicine, and even to airborne and satellite applications. Benefiting from recent technological developments in microelectronics, fibre optics, and diode laser technology, atomic magnetometers can be deployed in systems, in which many (lightweight, small volume) sensor heads can be placed at a large distance (10 m and more) from the driving/readout optics and electronics. This opens the way to measure, e.g., very weak biomagnetic signals (heart and brain fields) from humans and animals in a non-invasive way, and to record spatial maps thereof.Until recently the magnetometers with highest sensitivity (about 1 fT Hz^(-1/2)) were SQUIDs (superconducting quantum interference device). Unfortunately, SQUID systems are expensive to build and only operate where cryogenic cooling to liquid helium temperatures is available. Today, the sensitivity range for atomic magnetometers becomes competitive with (or even surpasses) SQUID sensors. The promise of optical atomic sensors is in their potential to be miniaturized (the smallest sensor so far realized has a dimension of 12 mm^3). In principle, atomic magnetometers can be adapted to the requirements of many different applications, and thus extended into daily life where such technology is currently rare.In the above context, this proposal aims at investigating a newly discovered branch of atomic magnetometry which has been only poorly explored to date. The proposed atomic magnetometers measure the magnetic field by a phase-sensitive comparison of the atomic Larmor precession frequency (itself proportional to the field strength) with the frequency of specific external electromagnetic radiation interacting with the atoms. For precise and sensitive applications, the external frequency should be referenced to a frequency standard such as an atomic clock. The proposed technique will exploit the (hitherto unexplored) fact that vapour cell atomic clocks and vapour cell atomic magnetometers are based on similar interactions of atoms and electromagnetic (light, microwave/radio-frequency) radiation. Herein we will attack the (obvious) question of whether it is possible to develop a device consisting of a sensitive atomic magnetometer containing its own intrinsic time-reference in terms of an atomic clock. The goal of the project is to answer this question.The work will be based on a recent proposal originating from the Happer group at Princeton University exploiting the so-called push-pull pumping, a variant of coherent population trapping (CPT) spectroscopy. Since its discovery in 1976 the CPT effect was studied in various dilute atomic samples (vapors, beams, condensates) and was applied in a number of fundamental experiments. The CPT effect has found applications in atom cooling to reach sub-Doppler and sub-photon recoil temperatures. The anomalously steep dispersion of CPT resonances exhibit have allowed the preparation of ultra-slow light, used for probing Bose-Einstein condensates, and provide potential applications in quantum communication and optical data storage. Here we focus on the fact that the push-pull variant of CPT spectroscopy can access both magnetic field sensitive and magnetic field insensitive resonances. The enhancement of the resonance contrast in the case of push-pull excitation of hyperfine coherences (clock application) has already been proven, but its use in magnetometry has not yet been explored. Here we want to use a doubly modulated laser source to generate simultaneously both magnetically sensitive (magnetometer) and magnetically insensitive (clock) resonances in an atomic cesium vapour sample. In three phases we plan to build the necessary apparatus, to fully investigate the features of this novel light-atom interaction and finally to realize and characterize a self-referenced magnetometer. The (mainly) experimental work will be backed by theoretical model calculations for which suitable algebraic and numerical tools for quantifying the atom-light interaction will be developed.
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