109 research outputs found
Universal Thermometry for Quantum Simulation
Quantum simulation is a highly ambitious program in cold atom research
currently being pursued in laboratories worldwide. The goal is to use cold
atoms in optical lattice to simulate models for unsolved strongly correlated
systems, so as to deduce their properties directly from experimental data. An
important step in this effort is to determine the temperature of the system,
which is essential for deducing all thermodynamic functions. This step,
however, remains difficult for lattice systems at the moment. Here, we propose
a method based on a generalized fluctuation-dissipation theorem. It does not
reply on numerical simulations and is a universal thermometry for all quantum
gases systems including mixtures and spinor gases. It is also unaffected by
photon shot noise.Comment: 4 pages, 3 figures, title, abstract and introduction modifie
Critical Rotational Frequency for Superfluid Fermionic Gases across a Feshbach Resonance
We present a method to determine the critical rotational frequencies for
superfluidity of both uniform and trapped Fermi gases across wide Feshbach
resonance. It is found that as one approaches the resonance from the BCS side,
beyond a critical scattering length, pairing is so robust that superfluidity
cannot be destroyed by rotation. Moreover, the critical frequency has a
sequence of jumps revealing the appearance of Landau levels, which are
particularly prominent for systems up to a few thousand particles. For
rotational frequency below an "ultimate" critical frequency, defined to be the
lowest frequency at which the center of the cloud goes normal, a trapped gas
has a superfluid core surrounded by a normal gas, as seen in recent
experiments.Comment: 4 pages, 2 figures, published versio
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