Atomic-state diagnostics and optimization in cold-atom experiments

Abstract

We report on the creation, observation and optimization of superposition states of cold atoms. In our experiments, rubidium atoms are prepared in a magneto-optical trap and later, after switching off the trapping fields, Faraday rotation of a weak probe beam is used to characterize atomic states prepared by application of appropriate light pulses and external magnetic fields. We discuss the signatures of polarization and alignment of atomic spin states and identify main factors responsible for deterioration of the atomic number and their coherence and present means for their optimization, like relaxation in the dark with the strobed probing. These results may be used for controlled preparation of cold atom samples and in situ magnetometry of static and transient fields.

Tailored optical properties of an atomic medium by a narrow-bandwidth frequency comb

“…The change in the polarization state of the light field is a sensitive means of extracting the material properties and has a crucial role in high sensitive magnetometry to cosmology [1][2][3][4]. It has been engineered by controlling the optical activity in the vicinity of atomic resonances with the parameters of the input light field and impinging magnetic field.…”

“…It has been engineered by controlling the optical activity in the vicinity of atomic resonances with the parameters of the input light field and impinging magnetic field. The light amplitude and its polarization gets further altered over a narrow span of frequency around a two-photon Raman resonance [3][4][5]. It improves the sensitivity, precision, and flexibility at the application end.…”

Limitations of rotating-wave approximation in magnetic resonance: characterization and elimination of the Bloch–Siegert shift in magneto-optics

“…Despite growing importance of BBS, to our knowledge, the effect has not been taken into consideration in studies of nonlinear magneto-optical effects in alkali metal vapors [19,20] (although some estimates were given in [21]). Since these phenomena are widely used in modern quantum metrology, we find that thorough analysis of BSS is crucial to avoid systematic errors in precision magnetometry and spectroscopic measurements with warm and cold atoms [22,23].…”

“…NMOR is based on optical detection of medium's anisotropy (birefringence and/or dichroism) caused by magnetic perturbations of optically polarized medium. The perturbation may change populations and coherences of the atomic system, so the method is useful for sensitive monitoring of atomic states and their superpositions [23,26]. Important features of our system are: a possibility of application of either rotating or oscillating magnetic field under otherwise the same experimental conditions, generation of narrow (≈1 Hz) RF NMOR resonances, and measurements at ultra-low alternating-(RF-) field frequencies (ω/2π=1-100 Hz).…”

Production of large Bose-Einstein condensates in a magnetic-shield-compatible hybrid trap

“…Compressed magnetic traps exerting gradients of hundreds G/cm on the atoms can cause saturation issues [44][45][46], if we exclude atom chips. On the other hand, the smaller gradients that are typically used for magneto-optical trap (MOT) operation demonstrated full compatibility with properly designed shields [47,48], but are insufficient to provide the necessary elastic collisions rate to reach quantum degeneracy in magnetic traps via RF evaporative cooling.…”