A novel approach to quantitative spectroscopy of atoms in a magnetic field and applications based on an atomic vapor cell with L=λ

Abstract

We describe the so-called "λ-Zeeman method" to investigate individual hyperfine transitions between Zeeman sublevels of atoms in an external magnetic field of 0.1 mT ÷ 0.25 T. Atoms are confined in a nanocell with thickness L = λ, where λ is the resonant wavelength (794 nm or 780 nm for D1 or D2 line of Rb). Narrow resonances in the transmission spectrum of the nanocell are split into several components in a magnetic field; their frequency positions and probabilities depend on the B -field. Possible applications are described, such as magnetometers with nanometric spatial resolution and tunable atomic frequency references.

SELECTIVE AMPLIFICATION OF NARROW RESONANCE FORMED IN TRANSMISSION SPECTRUM OF Rb NANO-CELL IN MAGNETIC FIELD

“…Since the laser beam diameter is about 1 mm and the distance between the walls of the NTC equals to 794 nm, the time of flight of an atom through the beam diameter (which determines the interaction time t for the atoms flying perpendicularly to the laser beam) differs by, in average, three orders of magnitude from the time of flight between the walls, which determines the interaction time t for the atoms flying along the beam. Since for atoms flying perpendicularly to the laser beam the Doppler effect is strongly reduced the VSOP peaks are exactly on the atomic transition frequencies [5][6][7] . Eq.…”

“…λ is either 794 nm or 780 nm). For L = λ, spectrally-narrow velocity selective optical pumping (VSOP) resonances appear at laser intensities ~10 mW/cm 2 in the transmission spectrum of the NTC [5][6][7] . In the case where NTC is placed in external magnetic field these VSOPs are split into several new components, the number of which depends on the quantum numbers F of the lower and upper levels, while the amplitudes of the components and their frequency positions depend on B-field, which is convenient to study separately each individual atomic transition behavior (called "λ-Zeeman technique"), see Refs.…”

Active narrowband filtering, line narrowing and gain using ladder electromagnetically induced transparency in an optically thick atomic vapour

“…This is 4 orders of magnitude higher than used in other high resolution experiments on ladder EIT in Rb [21]. The cell windows are fabricated from polished sapphire windows with parallel faces, which are cut perpendicular to the C-axis to minimise birefringence as discussed in refs [27,28]. However, there is still some small residual birefringence.…”

Efficient technique for measuring laser frequency stability

“…The magnetic field strength (measured by a calibrated Hall probe) is controlled by a longitudinal motion of the ring magnet through a micrometer translation stage. The ring magnet produces a strongly inhomogeneous field, which varies, however, only by a few μT inside of the atomic vapor column because of its small thickness (780 nm) [21]. The possibility to substitute Helmholtz coils by a permanent magnet is an additional asset of the error signal formation in nanocells.…”