Abstract: A quantum medium is excited by laser light from a first electromagnetic source and is also exposed to radiation from a second electromagnetic source such that the radiation field from this second source is non-uniform in a direction transverse to the direction of passage of laser light though the quantum medium. The laser light that has passed through the quantum medium is detected by two photo detectors at two different locations transverse to the passage of laser light, with the light detected by each photo detector having passed through a substantially different region of the quantum medium than the light detected by the other photo detector, and with the radiation field from the second electromagnetic source having different intensities in these two regions. The different radiation field intensities in these two regions produce at each photo detector different intensity levels of the laser light that varies with the frequency of the second source of electromagnetic radiation.

Abstract: An extremely small and inexpensively manufactured physics package for an atomic frequency standard can be provided with a microwave cavity having non-critical dimensions that is driven in a substantially TEM mode by a lumped LC means, the cavity resonant frequency being primarily determined by the lumped LC means. The lumped LC means can be any structure or combination of elements providing, at a selected microwave reference frequency, a resonant inductance and capacitance. Examples of such lumped LC means include, preferably, a rod or wire conductively attached to a wall of the microwave cavity as a lumped inductance and extending into the cavity to form, at its other end, a gap with an opposing cavity wall as a lumped capacitance; or a pair of rods or wires conductively attached to opposing walls and extending therefrom as a lumped inductance to form a gap therebetween as a lumped capacitance.