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For cold samples of laser-cooled atoms to be useful in emerging technologies such as compact atomic clocks and sensors, it is necessary to achieve small sample sizes while retaining a large number of cold atoms. Achieving large atom numbers in a small system is a major challenge for producing miniaturized laser-cooled atomic clocks, since the number of captured atoms in a vapor-cell magneto-optical trap (MOT) scales as the fourth power of the laser beam diameter [1]. This strong dependence on size is fundamentally set by the maximum spontaneous light force ħkγ/2, where ħk is the photon momentum and γ/2 is the maximum spontaneous photon scatter rate of a saturated transition of linewidth γ. We are attempting to surmount the limit imposed by spontaneous emission by using bichromatic cooling [2] — a technique that uses stimulated emission to slow the atoms. We have built a table-top experiment that uses stimulated-emission bichromatic cooling to pre-cool rubidium atoms and dramatically enhance the trappable atom number in a small MOT. The apparatus lets us test how bichromatic cooling scales with miniaturization. Here we report on our first experimental results of cooling a thermal beam of rubidium atoms down to MOT capture velocities.

Atomic magnetometers based on absorption or polarization rotation of light in an alkali vapor have recently demonstrated sensitivities rivaling those of superconducting quantum interference devices (SQUIDs) [1]. Miniaturization of such devices containing vapor cells fabricated with micro—electro—mechanical (MEMS) technology has been the focus of development for the better part of the last decade. In this paper, we describe a portable magnetometry system with a sensitivity below 50 fT/√Hz at 100 Hz. The atomic magnetometer consists of a microfabricated sensor head that is fiber coupled to a control module consisting of a laser and electronics. We describe the construction of this system and present the results of sensitivity measurements with an emphasis on identifying and characterizing the source of 1/f (flicker) noise. This portable magnetometer system was developed to measure magnetocardiograms (MCG) of human subjects inside a shielded environment [2].

We describe the main features of a cold atom frequency standard based on coherent population trapping (CPT). We explain our particular CPT configuration and our experimental setup, and present simulations of the expected performance (stability and major systematics).