Enhancement of Xe-129 polarization by off-resonant spin exchange optical pumping

A high power narrow line width (38 W, 0.09 nm full width at half maximum) external cavity diode laser is investigated for rubidium spin exchange optical pumping of Xe-129. This tunable photon source has a constant line width, independent of operating power or wavelength within a 1 nm tuning range. When using this laser, an increase in the Xe-129 nuclear polarization is observed when optically pumping at a lower wavelength than the measured Rb electron D-1 absorption. The exact detuning from D1 for the highest polarization is dependent upon the gas density. Furthermore, at high power and/or high Rb density, a reduction in the polarization occurs at the optimum wavelength as previously reported in spin exchange optical pumping studies of He-3 which is consistent with high absorption close to the cell front face. These results are encouraging for moderate high throughput polarization of Xe-129 in the midpressure range of (0.5-2.0 amagat). (C) 2010 American Institute of Physics. [doi: 10.1063/1.3478707

Enhancement of Xe-129 polarization by off-resonant spin exchange optical pumping

A high power narrow line width (38 W, 0.09 nm full width at half maximum) external cavity diode laser is investigated for rubidium spin exchange optical pumping of Xe-129. This tunable photon source has a constant line width, independent of operating power or wavelength within a 1 nm tuning range. When using this laser, an increase in the Xe-129 nuclear polarization is observed when optically pumping at a lower wavelength than the measured Rb electron D-1 absorption. The exact detuning from D1 for the highest polarization is dependent upon the gas density. Furthermore, at high power and/or high Rb density, a reduction in the polarization occurs at the optimum wavelength as previously reported in spin exchange optical pumping studies of He-3 which is consistent with high absorption close to the cell front face. These results are encouraging for moderate high throughput polarization of Xe-129 in the midpressure range of (0.5-2.0 amagat). (C) 2010 American Institute of Physics. [doi: 10.1063/1.3478707

Scanning a photonic crystal slab nanocavity by condensation of xenon

Allowing xenon or nitrogen gas to condense onto a photonic crystal slab nanocavity maintained at 10–20 K results in shifts of the nanocavity mode wavelength by as much as 5 nm (~=4 meV). This occurs in spite of the fact that the mode defect is achieved by omitting three holes to form the spacer. This technique should be useful in changing the detuning between a single quantum dot transition and the nanocavity mode for cavity quantum electrodynamics experiments, such as mapping out a strong coupling anticrossing curve. Compared with temperature scanning, it has a much larger scan range and avoids phonon broadening

Huge First-Order Metamagnetic Transition in the Paramagnetic Heavy-Fermion System CeTiGe

We report on the observation of large, step-like anomalies in the magnetization ($\Delta M = 0.74$\,$\mu_{\rm B}$/Ce), in the magnetostriction ($\Delta l/l_{0} = 2.0 \cdot 10^{-3}$), and in the magnetoresistance in polycrystals of the paramagnetic heavy-fermion system CeTiGe at a critical magnetic field $\mu_0 H_c \approx$ 12.5\,T at low temperatures. The size of these anomalies is much larger than those reported for the prototypical heavy-fermion metamagnet CeRu$_2$Si$_2$. Furthermore, hysteresis between increasing and decreasing field data indicate a real thermodynamic, first-order type of phase transition, in contrast to the crossover reported for CeRu$_2$Si$_2$. Analysis of the resistivity data shows a pronounced decrease of the electronic quasiparticle mass across $H_c$. These results establish CeTiGe as a new metamagnetic Kondo-lattice system, with an exceptionally large, metamagnetic transition of first-order type at a moderate field.Comment: 5 pages, 4 figure