Saturated-absorption spectroscopy revisited: atomic transitions in strong magnetic fields (>20 mT) with a micrometer-thin cell

The existence of crossover resonances makes saturated-absorption (SA) spectra very complicated when external magnetic field B is applied. It is demonstrated for the first time, to the best of our knowledge, that the use of micrometric-thin cells (MTCs, L≈40  μm) allows application of SA for quantitative studies of frequency splitting and shifts of the Rb atomic transitions in a wide range of external magnetic fields, from 0.2 up to 6 kG (20-600 mT). We compare the SA spectra obtained with the MTC with those obtained with other techniques and present applications for optical magnetometry with micrometer spatial resolution and a broadly tunable optical frequency lock.

Detecting domain walls of axionlike models using terrestrial experiments

Stable topological defects of light (pseudo)scalar fields can contribute to the Universe's dark energy and dark matter. Currently, the combination of gravitational and cosmological constraints provides the best limits on such a possibility. We take an example of domain walls generated by an axionlike field with a coupling to the spins of standard-model particles and show that, if the galactic environment contains a network of such walls, terrestrial experiments aimed at the detection of wall-crossing events are realistic. In particular, a geographically separated but time-synchronized network of sensitive atomic magnetometers can detect a wall crossing and probe a range of model parameters currently unconstrained by astrophysical observations and gravitational experiments.

Application of continuous wavelet transform for determination of fiber birefringence

Measurements of the group-birefringence dispersion of a microstructured optical fiber using the wavelength-scanning technique are reported. Resulting interferograms are processed using the continuous wavelet transform. We discuss application of this approach for determination of birefringence of few-mode fibers and show that with careful analysis it is possible to determine birefringence dispersion of the higher-order modes in optical fibers.

Analysis and calibration of absorptive images of Bose-Einstein condensate at nonzero temperatures

We describe the method allowing quantitative interpretation of absorptive images of mixtures of Bose-Einstein condensate and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction and eliminates arbitrariness of most of the previous approaches. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group.

Production and detection of atomic hexadecapole at Earth's magnetic field

Optical magnetometers measure magnetic fields with extremely high precision and without cryogenics. However, at geomagnetic fields, important for applications from landmine removal to archaeology, they suffer from nonlinear Zeeman splitting, leading to systematic dependence on sensor orientation. We present experimental results on a method of eliminating this systematic error, using the hexadecapole atomic polarization moment. In particular, we demonstrate selective production of the atomic hexadecapole moment at Earth's magnetic field and verify its immunity to nonlinear Zeeman splitting. This technique promises to eliminate directional errors in all-optical atomic magnetometers, potentially improving their measurement accuracy by several orders of magnitude.

Selective addressing of high-rank atomic polarization moments

We describe a method of selective generation and study of polarization moments of up to the highest-rank kappa=2F possible for a quantum state with total angular momentum F. The technique is based on nonlinear magneto-optical rotation with frequency-modulated light. Various polarization moments are distinguished by the periodicity of light-polarization rotation induced by the atoms during Larmor precession and exhibit distinct light-intensity and frequency dependences. We apply the method to study polarization moments of 87Rb atoms contained in a vapor cell with antirelaxation coating. Distinct ultranarrow (1-Hz wide) resonances, corresponding to different multipoles, appear in the magnetic-field dependence of the optical rotation. The use of the highest-multipole resonances supported by a given system has important applications in quantum and nonlinear optics and in magnetometry.