Publication Date:
2009-12-08
Description:
Classical ratchet potentials, which alternate a driving potential with periodic random dissipative motion, can account for the operation of biological motors. We demonstrate the operation of a quantum ratchet, which differs from classical ratchets in that dissipative processes are absent within the observation time of the system (Hamiltonian regime). An atomic rubidium Bose-Einstein condensate is exposed to a sawtooth-like optical lattice potential, whose amplitude is periodically modulated in time. The ratchet transport arises from broken spatiotemporal symmetries of the driven potential, resulting in a desymmetrization of transporting eigenstates (Floquet states). The full quantum character of the ratchet transport was demonstrated by the measured atomic current oscillating around a nonzero stationary value at longer observation times, resonances occurring at positions determined by the photon recoil, and dependence of the transport current on the initial phase of the driving potential.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Salger, Tobias -- Kling, Sebastian -- Hecking, Tim -- Geckeler, Carsten -- Morales-Molina, Luis -- Weitz, Martin -- New York, N.Y. -- Science. 2009 Nov 27;326(5957):1241-3. doi: 10.1126/science.1179546.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Angewandte Physik, Wegelerstrasse 8, 53115 Bonn, Germany. salger@iap.uni-bonn.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19965469" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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