Observation of the phase of a Raman oscillation

Pan Hu, Stanley Geschwind, Thomas M. Jedju

B. Dubetsky

It is proposed to use rectangular Raman pulses for the technique of sequential large momentum transfer. It is shown that the small parameters that make it possible to use this technology for precision atom interferometry can be 40--200 times smaller than in the case of the Bragg regime. It is predicted that in the case of a nonequidistant timing of auxiliary pulses, one can observe oscillations in time of the interference picture with a period inversely proportional to the recoil frequency. Such an observation would be confirmation that Mach-Zehnder atom interference is a phenomenon caused by the quantization of the atomic center-of-mass motion. This effect is calculated for any shape of pulses. One can observe it in the Bragg regime as well. It is proposed to use noncontinuous composite Raman pulses as auxiliary beam splitters so that the effective Rabi frequency remains unchanged for the entire process. The gravity phase of an atomic interferometer is calculated for any shape, duration, and timing of Raman pulses, including the Bragg regime. The phase corrections caused by the finite pulses' durations are also calculated for the rectangular Raman pulse shape.

Bernd Crasemann

Matt Poelker, Prem Kumar, Philip Hemmer

We report observing Raman-shifted oscillation within a ring cavity containing cesium vapor and pumped with the output of a single-frequency diode laser tuned near the D2 line. The oscillation is shifted from the diode-laser pump frequency by ≃9 GHz, the hyperfine splitting of the 6S1/2 ground state of cesium. Many different transverse modes of oscillation are observed for slight variations in the cavity alignment. In addition, the oscillation is observed to turn on and off at 60 Hz as a result of the pump-frequency fluctuations associated with the line noise on the diode-laser drive current. The pump-frequency fluctuations (≃10 MHz) are small compared with the free spectral range (175 MHz) of the ring cavity. These characteristics indicate that the Raman oscillation in cesium vapor is narrow-band, similar to the behavior observed in sodium vapor.1–3 As little as 30 mW of pump power is required for oscillation when highly reflective cavity optics are used. We have obtained 0.5 mW of Raman-shifted output with an appropriate output coupler at 65 mW of pump power.

Sung Jong Park, Hyuck Cho, Taeg Yong Kwon +1 more

The temporal evolution of coherent population trapping (CPT) was observed in rubidium atomic vapor when sudden changes were made to the detuning of a weak Raman field. The subsequent creation and destruction of CPT are caused by the temporal oscillations of optically induced Raman coherence, with their period depending on the Raman detuning. The oscillating signal was observed over a time of order of tens of milliseconds, and the dependence of the relaxation time on the cell temperature and laser power were investigated. The main features of the experimental observations were well explained by the time-dependent density-matrix equations.

Carla Buzano, Mario Rasetti, P. T. Valabrega