Self-ordering and cavity cooling using a train of ultrashort pulses (CROSBI ID 283447)
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Podaci o odgovornosti
Torggler, Valentin ; Krešić, Ivor ; Ban, Ticijana ; Ritsch, Helmut
engleski
Self-ordering and cavity cooling using a train of ultrashort pulses
A dilute atomic gas in an optical resonator exhibits a phase transition from a homogeneous density to crystalline order when laser illuminated orthogonal to the resonator axis. We study this well-known self-organization phenomenon for a generalized pumping scheme using a femtosecond pulse train with a frequency spectrum spanning a large bandwidth covering many cavity modes. We show that due to simultaneous scattering into adjacent longitudinal cavity modes the induced light forces and the atomic dynamics becomes nearly translation-invariant along the cavity axis. In addition the laser bandwidth introduces a new correlation length scale within which clustering of the atoms is energetically favorable. Numerical simulations allow us to determine the self-consistent ordering threshold power as function of bandwidth and atomic cloud size. We find strong evidence for a change from a second order to a first order self-ordering phase transition with growing laser bandwidth when the size of the atomic cloud gets bigger than the clustering length. An analysis of the cavity output reveals a corresponding transition from a single to a double pulse traveling within the cavity. This doubles the output pulse repetition rate and creates extra substructures in close analogy to a time crystal formation in the cavity output. Simulations also show that multi-mode operation significantly improves cavity cooling generating lower kinetic temperatures at a much faster cooling rate.
femtosecond-laser, cold-atoms
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Podaci o izdanju
22 (6)
2020.
063003-1-063003-15
objavljeno
1367-2630
10.1088/1367-2630/ab85a8