489 research outputs found
The Efimov effect in lithium 6
We analyse the recent experiments investigating the low-energy physics of
three lithium 6 atoms in different internal states with resonant two-body
scattering lengths. All observed features are qualitatively consistent with the
expected Efimov effect, i.e. the effective universal three-body attraction that
arises for large values of the scattering lengths. However, we find that a
quantitative description at negative energy requires non-universal two- and
three-body corrections due to presently unknown behaviour at short distance. An
attempt to implement these corrections is made through energy-dependent
parameters fitted to the experimental data.Comment: 12 pages, 8 figures. Same as published version. Contains additions
detailing the derivation of some formulae;
http://dx.doi.org/10.1016/j.crhy.2010.12.00
Determining the Continuous Family of Quantum Fisher Information from Linear Response Theory
The quantum Fisher information represents the continuous family of metrics on
the space of quantum states and places the fundamental limit on the accuracy of
quantum state estimation. We show that the entire family of the quantum Fisher
information can be determined from linear response theory through generalized
covariances. We derive the generalized fluctuation-dissipation theorem that
relates the linear response function to generalized covariances and hence
allows us to determine the quantum Fisher information from linear response
functions, which is experimentally measurable quantities. As an application, we
examine the skew information, which is one of the quantum Fisher information,
of a harmonic oscillator in thermal equilibrium, and show that the equality of
the skew information-based uncertainty relation holds.Comment: 8 pages, 1 figur
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