802 research outputs found
: A Unique Mott Hubbard Insulator
We discuss the recently discovered system , a realization
of an exactly solvable model proposed two decades earlier. We propose its
interpretation as a Mott Hubbard insulator. The possible superconducting phase
arising from doping is explored, and its nature as well as its importance for
testing the RVB theory of superconductivity are discussed.Comment: 18 pages,7 figures, Based on Invited Talk at 16th Nishinomiya Yukawa
memorial symposium, Nov 13-14, Nishinomiya. To appear in Progress in
Theoretical Physics, Suppliment 145(2002
Anisotropic Isometric Fluctuation Relations in experiment and theory on a self-propelled rod
The Isometric Fluctuation Relation (IFR) [P.I. Hurtado et al., PNAS 108, 7704
(2011)] relates the relative probability of current fluctuations of fixed
magnitude in different spatial directions. We test its validity in an
experiment on a tapered rod, rendered motile by vertical vibration and immersed
in a sea of spherical beads. We analyse the statistics of the velocity vector
of the rod and show that they depart significantly from the IFR of Hurtado et
al. Aided by a Langevin-equation model we show that our measurements are
largely described by an anisotropic generalization of the IFR [R. Villavicencio
et al., EPL 105, 30009 (2014)], with no fitting parameters, but with a
discrepancy in the prefactor whose origin may lie in the detailed statistics of
the microscopic noise. The experimentally determined Large-Deviation Function
of the velocity vector has a kink on a curve in the plane.Comment: 6 pages, 4 figure
Active elastic dimers: self-propulsion and current reversal on a featureless track
We present a Brownian inchworm model of a self-propelled elastic dimer in the
absence of an external potential. Nonequilibrium noise together with a
stretch-dependent damping form the propulsion mechanism. Our model connects
three key nonequilibrium features -- position-velocity correlations, a nonzero
mean internal force, and a drift velocity. Our analytical results, including
striking current reversals, compare very well with numerical simulations. The
model unifies the propulsion mechanisms of DNA helicases, polar rods on a
vibrated surface, crawling keratocytes and Myosin VI. We suggest experimental
realizations and tests of the model.Comment: 4 page
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