We report the selective population of Rb or Cs
np 2P23 (
n=5, 6;
F=4, 5) hyperfine states by the photodissociation of a transient, alkali-rare gas diatomic molecule. Circularly polarized (${\ensuremath{\sigma}}^{\ensuremath{-}}$), amplified spontaneous emission (ASE) on the
D2 line of Rb or Cs (780.0 and 852.1 nm, respectively) is generated when Rb-Xe or Cs-Xe ground state collision pairs are photoexcited by a ${\ensuremath{\sigma}}^{+}$-polarized optical field having a wavelength within the
D2 blue satellite continuum, associated with the $B{^{2}\mathrm{\ensuremath{\Sigma}}}_{\frac{1}{2}}^{+}\ensuremath{\leftarrow}X{^{2}\mathrm{\ensuremath{\Sigma}}}_{\frac{1}{2}}^{+}$ ($\text{free}\ensuremath{\leftarrow}\text{free}$) transition of the diatomic molecule. The degree of spin polarization of Cs (
6p 2P23), specifically, is found to be dependent on the interatomic distance (
R) at which the excited complex is born, a result attributed to the structure of the $B{^{2}\mathrm{\ensuremath{\Sigma}}}_{\frac{1}{2}}^{+}$ state. For Cs-Xe atomic pairs, tuning the wavelength of the optical field from 843 to 848 nm varies the degree of circular polarization of the ASE from 63% to almost unity because of the perturbation, in the $5\ensuremath{\le}R\ensuremath{\le}6\text{ }\text{ }\AA{}$ interval, of the ${^{2}\mathrm{\ensuremath{\Sigma}}}_{\frac{1}{2}}^{+}$ potential by a $d\ensuremath{\sigma}$ molecular orbital associated with a higher $^{2}\mathrm{\ensuremath{\Lambda}}$ electronic state. Monitoring only the Cs
6p 2P23 spin polarization reveals a previously unobserved interaction of CsXe ($B{^{2}\mathrm{\ensuremath{\Sigma}}}_{\frac{1}{2}}^{+}$) with the lowest vibrational levels of a $^{2}\mathrm{\ensuremath{\Lambda}}$ state derived from Cs
(5d)+Xe. By inserting a molecular intermediate into the alkali atom excitation mechanism, these experiments realize electronic spin polarization through populating no more than two
np 2P23 hyperfine states, and demonstrate a sensitive spectroscopic probe of
R-dependent state-state interactions and their impact on interatomic potentials.
Nuclear-spin states of gaseous-state Cs atoms in the ground state are optically manipulated using a Ti:sapphire laser in a magnetic field of 1.516 T, in which optical coupling of the nuclear-spin states is achieved through hyperfine interactions between electrons and nuclei. The steady-state population distribution in the hyperfine Zeeman sublevels of the ground state is detected by using a tunable diode laser. Furthermore, the state population transfer among the hyperfine Zeeman sublevels, which results from the collision-induced modification δ a ( S · I ) of the hyperfine interaction of Cs in the ground state due to stochastic collisions between Cs atoms and buffer-gas molecules, is studied at different buffer-gas pressures. The experimental results show that high-field optical pumping and the small change δ a ( S · I ) of the hyperfine interaction can strongly cause the state population transfer and spin-state interchange among the hyperfine Zeeman sublevels. The calculated results maybe explain the steady-state population in hyperfine Zeeman sublevels in terms of rates of optical-pumping, electron-spin flip, nuclear spin flip, and electron-nuclear spin flip-flop transitions among the hyperfine Zeeman sublevels of the ground state of Cs atoms. This method may be applied to the nuclear-spin-based solid-state quantum computation.
Spin‐exchange collisions between optically pumped alkali atoms and rare gas atoms can polarize the nuclei of rare gas atoms. We present calculations which indicate that the process should be readily modified by relatively weak (<1 KW/cm2) CW laser radiation tuned in the vicinity of the Rb‐rare gas 5sΣ−6sΣ free‐bound molecular transition. Full coupling of the spin‐polarized Rb electronic spin to the rare gas nuclear spin in the excited state lifetime leads to an estimate for Rb–Xe of a cross section σ≂10−22 Pcm2, where P is the laser power in KW/cm2.
The quantum electrodynamic description of circularly and linearly polarized, single mode radiation exciting atomic transitions in a hyperfine manifold is extended to the more general case of elliptic polarization. Calculations for the sodium D2 line are tested by observing the line polarization of the resonance flourescence scattered perpendicular to the plane containing laser and atomic beams as a function of the laser polarization. Very good agreement between the calculations and the measurements is achieved. It is demonstrated that predetermined populations and substate coherences can be engineered by optically pumping the transition with the appropriately polarized radiation.
The evolution of the hyperfine structure magnetic sublevel populations of 87 Rb and 133 Cs atoms in resonant linearly polarized laser fields is theoretically analyzed. Analytical expressions are obtained for stationary populations of the magnetic sublevels of the ground state 5 2 S 1/2 F g = 1, F f = 2 in 87 Rb and 6 2 S 1/2 F g = 3, F f = 4 in 133 Cs under optical pumping at the F g ↔ F e = F g and F f ↔ F e = F f transitions of the D 2 lines ( n 2 S 1/2 n 2 P 3/2 ) versus the initial populations. The characteristic population stabilization time are obtained by numerical solution for the density matrix equations, depending on the intensity of the laser fields and the detuning of the optical resonance. It is shown that the alternation of the polarization direction of the laser field at the transition F f ↔ F e = F f almost completely transfers atoms to the lower sublevel of the "clock" M1 transition F g M = 0 ↔ F f M = 0 in rubidium and cesium frequency standards, which proportionally increases the signal of the recording system.