Marcin E. Witkowski

Absolute frequency measurement of rubidium 5S–7S two-photon transitions

We report the absolute frequency measurements of rubidium 5S-7S two-photon transitions with an optical frequency comb. The digital lock to the transition, the procedures of evaluating the accuracy budget and measurements of the frequency with the optical frequency comb are tested with a simple setup for the sake of comparison of two optical lattice strontium clocks. The narrow, two-photon transition, 5S-7S (760 nm) is insensitive to a magnetic field and promising candidate for frequency standard. The preformed tests yield the transition frequency with accuracy better than reported previously.

Free-fall expansion of finite-temperature Bose–Einstein condensed gas in the non-Thomas–Fermi regime

We report on our study of the free-fall expansion of a finite-temperature Bose–Einstein condensed cloud of 87Rb. The experiments are performed with a variable total number of atoms while keeping constant the number of atoms in the condensate. The results provide evidence that the Bose–Einstein condensate dynamics depends on the interaction with thermal fraction. In particular, they provide experimental evidence that the thermal cloud compresses the condensate.

Effect of thermal annealing in air on scintillation properties of LuAG and LuAG:Pr

Pure and Pr-activated Lu3Al5O12 (LuAG) crystals have been grown by the Czochralski method. In order to improve the scintillation properties, several samples have been annealed in air. Various annealing temperatures and periods of time have been tested to determine optimal conditions in the way of scintillation yield and energy resolution enhancement. The largest increase of yield of LuAG:Pr (17%), accompanied by a distinct decrease of resolution, has been observed after annealing at 1100°C for 48 h. On the contrary, in case of undoped LuAG no significant changes following thermal annealing have been noticed.

Dual Hg-Rb magneto-optical trap

We present a two-species laser cooling apparatus capable of simultaneously collecting Rb and Hg atomic gases into a magneto-optical trap (MOT). The atomic sources, laser system, and vacuum set-up are described. While there is a loss of Rb atoms in the MOT due to photoionization by the Hg cooling laser, we show that it does not prevent simultaneous trapping of Rb and Hg. We also demonstrate interspecies collision-induced losses in the 87Rb-202Hg system.

Optimal geometry for efficient loading of an optical dipole trap

One important factor which determines efficiency of loading cold atoms into an optical dipole trap from a magneto-optical trap is the distance between the trap centers. By studying this efficiency for various optical trap depths (2--110 mK) we find that for optimum dipole trap loading, longitudinal displacements up to 15 mm are necessary. An explanation for this observation is presented and compared with other work and a simple analytical formula is derived for the optimum distance between the trap centers.

Matter-wave interference versus spontaneous pattern formation in spinor Bose-Einstein condensates

We describe effects of matter-wave interference of spinor states in the

Experimental set-up for study of collisions of cold mercury atoms for optical frequency clocks

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Testing optical clock calibration procedures: Absolute frequency measurement of rubidium 5S-7S two-photon transitions

Rb Bose-Einstein condensate. The components of the

Studies of light yield as a function of temperature and low temperature thermoluminescence of Gd3Al2Ga3O12:Ce scintillator crystals

F=2

Effect of thermal annealing on light yield, low temperature thermoluminescence, and time profiles of LuAG:Pr scintillator crystals

manifold are populated by forced Majorana transitions and then fall freely due to gravity in an applied magnetic field. Weak inhomogeneities of the magnetic field, present in the experiment, impose relative velocities onto different