arXiv subjects

D. R. Fredkin

Publications and source records attributed to D. R. Fredkin.

3 recordsLinked to original sources

arXiv2008

Theory of Thermal Motion in Electromagnetically Induced Transparency: Diffusion, Doppler, Dicke and Ramsey

We present a theoretical model for electromagnetically induced transparency (EIT) in vapor, that incorporates atomic motion and velocity-changing collisions into the dynamics of the density-matrix distribution. Within a unified formalism we demonstrate various motional effects, known for EIT in vapor: Doppler-broadening of the absorption spectrum; Dicke-narrowing and time-of-flight broadening of the transmission window for a finite-sized probe; Diffusion of atomic coherence during storage of light and diffusion of the light-matter excitation during slow-light propagation; and Ramsey-narrowing of the spectrum for a probe and pump beams of finite-size.

quant-ph↗

arXiv2007

Slowing the Decay of an Excited Atom by the Presence of a Detector

The decay of an excited is shown to slow down in the presence of a photo detector. This is similar to the behavior of an atom in a mistuned cavity, and under the conditions of the quantum Zeno effect. No external perturbing field is applied to measure the survival probability of the unstable state.

quant-ph↗

arXiv2007

Theory of Dicke narrowing in coherent population trapping

The Doppler effect is one of the dominant broadening mechanisms in thermal vapor spectroscopy. For two-photon transitions one would naively expect the Doppler effect to cause a residual broadening, proportional to the wave-vector difference. In coherent population trapping (CPT), which is a narrow-band phenomenon, such broadening was not observed experimentally. This has been commonly attributed to frequent velocity-changing collisions, known to narrow Doppler-broadened one-photon absorption lines (Dicke narrowing). Here we show theoretically that such a narrowing mechanism indeed exists for CPT resonances. The narrowing factor is the ratio between the atom's mean free path and the wavelength associated with the wave-vector difference of the two radiation fields. A possible experiment to verify the theory is suggested.

quant-ph↗