6,235 research outputs found
Towards a Fisher-information description of complexity in de Sitter universe
Recent developments on holography and quantum information physics suggest
that quantum information theory come to play a fundamental role in
understanding quantum gravity. Cosmology, on the other hand, plays a
significant role in testing quantum gravity effects. How to apply this idea to
a realistic universe is still missing. Here we show some concepts in quantum
information theory have their cosmological descriptions. Particularly, we show
complexity of a tensor network can be regarded as a Fisher information
measure(FIM) of a dS universe, followed by several observations: (i) the
holographic entanglement entropy has a tensor-network description and admits a
information-theoretical interpretation, (ii) on-shell action of dS spacetime
has a same description of FIM, (iii) complexity/action(CA) duality holds for dS
spacetime. Our result is also valid for gravity, whose FIM exhibits the
same features of a recent proposed norm complexity.Comment: 18 pages, 3 figures. v2: improvements to presentation, fixes typos
and matches published versio
Transition from Tonks-Girardeau gas to super-Tonks-Girardeau gas as an exact many-body dynamics problem
We investigate transition of a one-dimensional interacting Bose gas from a
strongly repulsive regime to a strongly attractive regime, where a stable
highly excited state known as the super Tonks-Girardeau gas was experimentally
realized very recently. By solving exact dynamics of the integrable
Lieb-Liniger Bose gas, we demonstrate that such an excited gas state can be a
very stable dynamic state. Furthermore we calculate the breathing mode of the
super Tonks-Girardeau gas which is found to be in good agreement with
experimental observation. Our results show that the highly excited super
Tonks-Girardeau gas phase can be well understood from the fundamental theory of
the solvable Bose gas.Comment: 4 pages, 4 figures, version to appear in Phys. Rev. A as a Rapid
Communicatio
Realization of effective super Tonks-Girardeau gases via strongly attractive one-dimensional Fermi gases
A significant feature of the one-dimensional super Tonks-Girardeau gas is its
metastable gas-like state with a stronger Fermi-like pressure than for free
fermions which prevents a collapse of atoms. This naturally suggests a way to
search for such strongly correlated behaviour in systems of interacting
fermions in one dimension. We thus show that the strongly attractive Fermi gas
without polarization can be effectively described by a super Tonks-Girardeau
gas composed of bosonic Fermi pairs with attractive pair-pair interaction. A
natural description of such super Tonks-Girardeau gases is provided by Haldane
generalized exclusion statistics. In particular, we find that they are
equivalent to ideal particles obeying more exclusive statistics than
Fermi-Dirac statistics.Comment: 4 pages, 2 figure
Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions
Dijet, dihadron, hadron-jet angular correlations have been reckoned as
important probes of the transverse momentum broadening effects in relativistic
nuclear collisions. When a pair of high-energy jets created in hard collisions
traverse the quark-gluon plasma produced in heavy-ion collisions, they become
de-correlated due to the vacuum soft gluon radiation associated with the
Sudakov logarithms and the medium-induced transverse momentum broadening. For
the first time, we employ the systematical resummation formalism and establish
a baseline calculation to describe the dihadron and hadron-jet angular
correlation data in and peripheral collisions where the medium effect
is negligible. We demonstrate that the medium-induced broadening and the so-called jet quenching parameter can be
extracted from the angular de-correlations observed in collisions. A
global analysis of dihadron and hadron-jet angular correlation data
renders the best fit for a
quark jet at RHIC top energy. Further experimental and theoretical efforts
along the direction of this work shall significantly advance the quantitative
understanding of transverse momentum broadening and help us acquire
unprecedented knowledge of jet quenching parameter in relativistic heavy-ion
collisions.Comment: 6 pages, 3 figure
Geometric phase and quantum phase transition in an inhomogeneous periodic XY spin-1/2 model
The notion of geometric phase has been recently introduced to analyze the
quantum phase transitions of many-body systems from the geometrical
perspective. In this work, we study the geometric phase of the ground state for
an inhomogeneous period-two anisotropic XY model in a transverse field. This
model encompasses a group of familiar spin models as its special cases and
shows a richer critical behavior. The exact solution is obtained by mapping on
a fermionic system through the Jordan-Wigner transformation and constructing
the relevant canonical transformation to realize the diagonalization of the
Hamiltonian coupled in the -space. The results show that there may exist
more than one quantum phase transition point at some parameter regions and
these transition points correspond to the divergence or extremum properties of
the Berry curvature.Comment: 6 pages, 3 figures. As a backup of a previous work and some typos in
the published version are fixe
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