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SYKM: Lichtausbreitung in kohärent präparierten Medien
SYKM 1: Lichtausbreitung in kohärent präparierten Medien I
SYKM 1.1: Invited Talk
Thursday, March 5, 2009, 14:00–14:30, VMP 6 HS-D
Diffusion of Slow and Stored Light in Vapor — •N. Davidson1, O. Firstenberg2, M. Shuker2, R. Pugatch1, and A. Ron2 — 1Department of Physics of Complex Systems, Weizmann Institute of Science, Israel — 2Physics Department, Technion, Israel
Electromagnetically induced transparency (EIT) occurs when a pump field and a probe field, excite two atomic levels to a common upper level, creating a coherent superposition that reduces the absorption of the probe. Due to the narrow transparency line, the group-velocity of the probe pulse is remarkably small. Moreover, if the pump is shut off during the slow probe propagation, the probe is stored in the atomic ensemble, to be retrieved upon reopening the pump.
We present an extensive theoretical and experimental study of the effect of thermal atomic motion on EIT. Due to frequent collisions with the much denser noble buffer gas, the atomic motion is diffusive, which leads to various interesting phenomena. A direct consequence of the diffusion of atoms is the diffusion of a stored image throughout the storage duration [1]. The complex amplitude undergoes diffusion and therefore interference occurs. Specifically, high-order Gaussian transverse-modes are topologically stable and self-similar upon storage [2]. During the slow propagation of the probe in the medium, the combined light-matter excitation exhibits diffusion and diffusion-like behavior.
We also study motional broadening and narrowing mechanisms on the EIT spectra, such as Doppler broadening, Dicke narrowing, and Ramsey narrowing [3]. We present spectroscopic measurements which manifest these mechanisms. Due to its quadratic dependence on the transverse wave-numbers, the Dicke-narrowing term is also responsible for many interesting spatial effects. Most intriguing is a regime where the Dicke term dominates the dispersion, and may be utilized to cancel the paraxial optical diffraction [4], to manipulate the position of a localized probe beam, and to induce effective electric and magnetic fields that act on the probe's envelope. Finally, we present a regime where the EIT complex spectrum is universal, equals to the Laplace transform of the recurrence probability or a random walker, and depends only on the dimensionality of space [5].
[1] M. Shuker, O. Firstenberg, R. Pugatch, A. Ron, and N. Davidson, PRL 100, 223601 (2008). [2] R. Pugatch, M. Shuker, O. Firstenberg, A. Ron, and N. Davidson, PRL 98, 203601 (2007). [3] O. Firstenberg, M. Shuker, R. Pugatch, D. R. Fredkin, N. Davidson, and A. Ron, PRA 77, 043830 (2008). [4] O. Firstenberg, M. Shuker, N. Davidson, and A. Ron, PRL, in press. [5] R. Pugatch, O. Firstenberg, M. Shuker, and N. Davidson, submitted to PRL.