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Efficient Debanding Filtering for Inverse Tone Mapped High Dynamic Range Videos
FFLO correlation and free fluids in the one-dimensional attractive Hubbard model
In this Rapid Communication we show that low energy macroscopic properties of
the one-dimensional (1D) attractive Hubbard model exhibit two fluids of bound
pairs and of unpaired fermions. Using the thermodynamic Bethe ansatz equations
of the model, we first determine the low temperature phase diagram and
analytically calculate the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing
correlation function for the partially-polarized phase. We then show that for
such a FFLO-like state in the low density regime the effective chemical
potentials of bound pairs and unpaired fermions behave like two free fluids.
Consequently, the susceptibility, compressibility and specific heat obey simple
additivity rules, indicating the `free' particle nature of interacting fermions
on a 1D lattice. In contrast to the continuum Fermi gases, the correlation
critical exponents and thermodynamics of the attractive Hubbard model
essentially depend on two lattice interacting parameters. Finally, we study
scaling functions, the Wilson ratio and susceptibility which provide universal
macroscopic properties/dimensionless constants of interacting fermions at low
energy.Comment: In this Letter we analytically study FFLO pairing correlation and the
universal nature of the FFLO-like state. More detailed studies of this model
will be presented in arXiv:1710.08742 and arXiv:1708.0778
Rate-Distortion-Based Physical Layer Secrecy with Applications to Multimode Fiber
Optical networks are vulnerable to physical layer attacks; wiretappers can
improperly receive messages intended for legitimate recipients. Our work
considers an aspect of this security problem within the domain of multimode
fiber (MMF) transmission. MMF transmission can be modeled via a broadcast
channel in which both the legitimate receiver's and wiretapper's channels are
multiple-input-multiple-output complex Gaussian channels. Source-channel coding
analyses based on the use of distortion as the metric for secrecy are
developed. Alice has a source sequence to be encoded and transmitted over this
broadcast channel so that the legitimate user Bob can reliably decode while
forcing the distortion of wiretapper, or eavesdropper, Eve's estimate as high
as possible. Tradeoffs between transmission rate and distortion under two
extreme scenarios are examined: the best case where Eve has only her channel
output and the worst case where she also knows the past realization of the
source. It is shown that under the best case, an operationally separate
source-channel coding scheme guarantees maximum distortion at the same rate as
needed for reliable transmission. Theoretical bounds are given, and
particularized for MMF. Numerical results showing the rate distortion tradeoff
are presented and compared with corresponding results for the perfect secrecy
case.Comment: 30 pages, 5 figures, accepted to IEEE Transactions on Communication
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