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Seminars

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  • Title:From cooperative mechanical effects to super- and sub-radiance assisted cooling
  • Start Date/Time:2017-10-18 / 14:00
  • End Date/Time :2017-10-18 / 17:00
    • Speaker:Prof. Guin Dar Lin (林俊達 助理教授) Department of Physics, National Taiwan University
    • Place:Lecture Room A of NCTS, 4F, 3rd General Building, Nat'l Tsing Hua Univ.
    • Host:Prof. Ying-Cheng Chen (IAMS, Academia Sinica)
    • Decorative image
      Abstract:Cooperativity is many-body coherence that originates from exchange interaction in quantum many-body systems. Through explicit consideration of dipole-dipole interaction between atoms in an ensemble, the cooperativity leads to enhancement (superradiance) and suppression (subradiance) of relaxation of the atomic excitation. As a consequence, atoms' mechanical response to the light must be re-examined in this context. For instance, Doppler laser cooling relies on radiation pressure and the velocity dependent absorption spectrum. Novel and interesting coupled motional behavior can be expected in super- and sub-radiant atoms. We develop a theory to analyze the steady-state distribution of atoms. We find that the population in the subradiant states outnumbers that in the superradiant states due to optical pumping. Since the subradiant decay rates are smaller compared to that of a single atom case, leading to smaller thermal fluctuations, the temperature beyond the standard Doppler limit becomes possible.
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