A5055492542- Atomic and Subatomic Physics Research
- Quantum optics and atomic interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Dark Matter and Cosmic Phenomena
- Advanced MRI Techniques and Applications
- Magnetic Field Sensors Techniques
- Mechanical and Optical Resonators
- Magneto-Optical Properties and Applications
- Electrical and Bioimpedance Tomography
- Seismic Waves and Analysis
- Characterization and Applications of Magnetic Nanoparticles
- Cosmology and Gravitation Theories
- Earthquake Detection and Analysis
- Quantum, superfluid, helium dynamics
- Geophysics and Sensor Technology
- Geophysics and Gravity Measurements
- Inertial Sensor and Navigation
Leibniz Institute of Photonic Technology
2013-2025
University of Fribourg
2016-2023
Abstract Ultralight bosons such as axion-like particles are viable candidates for dark matter. They can form stable, macroscopic field configurations in the of topological defects that could concentrate matter density into many distinct, compact spatial regions small compared with Galaxy but much larger than Earth. Here we report results search transient signals from domain walls by using global network optical magnetometers exotic (GNOME) physics searches. We data, consisting correlated...
We present a portable optically pumped magnetometer instrument for ultrasensitive measurements within the Earth's magnetic field. The central part of system is sensor head operating MEMS-based Cs vapor cell in light-shift dispersed ${M}_{z}$ mode. It connected to compact, battery-driven electronics module by flexible cable. briefly review working principles device and detail realization both electronics. show shielded unshielded static field amplitude...
We demonstrate a way of operating an optically pumped magnetometer with miniaturized cesium cell using the light-narrowing effect. The setup shows improvement shot-noise-limited sensitivity ($42\phantom{\rule{0.16em}{0ex}}\mathrm{fT}/\sqrt{\mathrm{Hz}}$ in only $9.3\phantom{\rule{0.16em}{0ex}}{\mathrm{mm}}^{3}$ volume) due to suppression spin-exchange relaxation large extent and use strikingly increased fraction alkali-metal atoms for signal generation, working even...
We present an optically pumped magnetometer working in a new operational mode-the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use small alkali metal vapor cells identical properties integrated array structures, two such by circularly polarized opposite helicity; (4) subtraction the signals these...
Light (pseudo-)scalar fields are promising candidates to be the dark matter in Universe. Under certain initial conditions early Universe and/or with types of self-interactions, they can form compact dark-matter objects such as axion stars or $Q$-balls. Direct encounters searched for by using a global network atomic magnetometers. It is shown that range masses and radii not ruled out existing observations, terrestrial encounter rate $Q$-balls sufficiently high (at least once per year)...
We present an approach allowing optically pumped magnetometer (OPM) to be operated within the Earth’s magnetic field as a vector magnetometer, sensitive axis of which can freely defined. This enables measurement any component with same sensitivity. The OPM is realized by microfabricated cesium-vapor cell nitrogen buffer gas, immersed in constant homogeneous bias approximately <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:mn>730</a:mn><a:mspace...
We compare the performance of two methods for synchronization atomic spins in optically pumped magnetometers: intensity modulation pump light and classical M(x) method using B(1) field modulation. Both techniques use same set-up measure resulting features after passing a micro-fabricated Cs cell. The intensity-modulated pumping shows several advantages: better noise-limited magnetic sensitivity, misalignment between spin is excluded, magnetometer arrays without any cross-talk can be easily set up.
The Global Network of Optical Magnetometers to search for Exotic physics (GNOME) is a network geographically separated, time-synchronized, optically pumped atomic magnetometers that being used correlated transient signals heralding exotic physics. GNOME sensitive nuclear- and electron-spin couplings fields from astrophysical sources such as compact dark-matter objects (for example, axion stars domain walls). Properties the sensors sensitivity, bandwidth, noise characteristics are studied in...
We present a detailed experimental and theoretical study on the relaxation of spin coherence due to spin-exchange mechanism arising in electronic ground states alkali-metal vapor atoms. As opposed well-explored formation stretched state longitudinal geometry (magnetic field parallel laser propagation direction) we employ adapted hyperfine-selective optical pumping order suppress relaxation. By comparing measurements intrinsic rate cesium atoms with density-matrix simulations show that...
We have performed quantitative measurements of the variation on-resonance absorption coefficients ${\ensuremath{\kappa}}_{0}$ four hyperfine components Cs ${D}_{1}$ transition as a function laser power $P$, for pumping with linearly and circularly polarized light. Sublevel populations derived from rate equations assuming isotropic population relaxation (at ${\ensuremath{\gamma}}_{1}$) yield algebraic ${\ensuremath{\kappa}}_{0}(P)$ dependences that do not reproduce experimental findings vapor...
A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale cells is presented. This offers similar stability as achievable with conventional DAVLL using bulk cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. be controlled either by changing temperature of or application buffer gas under an appropriate pressure. particular, we...
The performance of an optically pumped Mx magnetometer with miniaturized Cs cell at earth's magnetic field strength (50 μT) is investigated. Operation using detuned high intensity laser light shown to be superior the conventional resonant operation in terms projected shot-noise-limited ( 50 fT/√Hz) and actual noise-limited sensitivity a noise compensation method. Zeeman shift effect, emerging due off-resonant circularly polarized radiation leading strong orientational dependence measurement,...
Most optically pumped magnetometers based on alkali atom vapor cells and by a single narrow-band laser suffer from loss of signal since atoms become trapped in the ground hyperfine states that are not coupled to beam. This can be counteracted additional optical repumping these ground-state levels. We study using cesium with partly overlapped splitting due their nitrogen buffer-gas filling. implement two methods compare them conventional case F=4 pumping: F=3 an repumper combined...
Abstract Numerous observations suggest that there exist undiscovered beyond‐the‐standard‐model particles and fields. Because of their unknown nature, these exotic fields could interact with standard model in many different ways assume a variety possible configurations. Here, an overview the global network optical magnetometers for physics searches (GNOME), ongoing experimental program designed to test wide range scenarios, is presented. The GNOME experiment utilizes worldwide shielded atomic...
We have investigated the dependence of lock-in-demodulated $$M_x$$ -magnetometer signals on orientation static magnetic field $$\mathbf {B}_{0}$$ interest. Magnetic resonance spectra for 2400 discrete orientations covering a $$4\pi$$ solid angle been recorded by PC-controlled steering and data acquisition system. Off-line fits previously derived lineshape functions allow us to extract relevant parameters (shape, amplitude, width, phase) represent their with respect laser beam propagation...
Numerous observations suggest that there exist undiscovered beyond-the-Standard-Model particles and fields. Because of their unknown nature, these exotic fields could interact with Standard Model in many different ways assume a variety possible configurations. Here we present an overview the Global Network Optical Magnetometers for Exotic physics searches (GNOME), our ongoing experimental program designed to test wide range scenarios. The GNOME experiment utilizes worldwide network shielded...
Abstract Spatial quantitative information about magnetic nanoparticle (MNP) distributions is a prerequisite for biomedical applications like hyperthermia and drug targeting. This can be gathered by means of magnetorelaxometry (MRX) imaging, where the relaxation previously aligned MNP’s moments measured sensitive magnetometers an inverse problem solved. To remove or minimize shielding in which MRX imaging carried out today, knowledge influence background fields on prerequisite. We show...
We show the operation of an optically pumped magnetometer array in a 50 μT magnetic field. The various components for fully optical and non-magnetic detector unit were constructed evaluated, from which prototype was assembled with fiber coupled electronics. In this magnetometers operated using intensity modulated method heated off-resonant laser. Calculations on temperature distribution used to design array. Different such characterized showed identical performance. Without applying noise...
Abstract Results are reported from the first full-scale search for transient signals exotic fields of astrophysical origin using data a newly constructed Earth-scale detector: Global Network Optical Magnetometers Exotic physics searches (GNOME). Data collected by GNOME consist correlated measurements optical atomic magnetometers located in laboratories all over world. searched patterns propagating through network consistent with composed ultralight bosons such as axion-like particles (ALPs)....
In mobile applications such as geomagnetic surveying, two major effects hamper the use of optically pumped magnetometers: dead zones, sensor orientations where sensors signal amplitude drops; and heading errors, a dependence measured magnetic field value on orientation. We present concept for an omnidirectional magnetometer to overcome both these effects. The uses cesium vapor cells, interrogated by circularly-polarized amplitude-modulated laser light split into beams running perpendicular...