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Kawai H.,Kyoto University | Yokokura Y.,International Center for Theoretical science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We analyze time evolution of a spherically symmetric collapsing matter from a point of view that black holes evaporate by nature. We first consider a spherical thin shell that falls in the metric of an evaporating Schwarzschild black hole of which the radius a(t) decreases in time. The important point is that the shell can never reach a(t) but it approaches a(t)-a(t)da(t)dt. This situation holds at any radius because the motion of a shell in a spherically symmetric system is not affected by the outside. In this way, we find that the collapsing matter evaporates without forming a horizon. Nevertheless, a Hawking-like radiation is created in the metric, and the object looks the same as a conventional black hole from the outside. We then discuss how the information of the matter is recovered. We also consider a black hole that is adiabatically grown in the heat bath and obtain the interior metric. We show that it is the self-consistent solution of Gμν=8πG〈Tμν〉 and that the four-dimensional Weyl anomaly induces the radiation and a strong angular pressure. Finally, we analyze the internal structures of the charged and the slowly rotating black holes. © 2016 American Physical Society. Source

Mishra T.,International Center for Theoretical science | Pai R.V.,Goa University | Mukerjee S.,Indian Institute of Science
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We study a system of hard-core boson on a one-dimensional lattice with frustrated next-nearest-neighbor hopping and nearest-neighbor interaction. At half filling, for equal magnitude of nearest- and next-nearest-neighbor hopping, the ground state of this system exhibits a first-order phase transition from a bond-ordered solid to a charge-density-wave solid as a function of the nearest-neighbor interaction. Moving away from half filling we investigate the system at incommensurate densities, where we find a supersolid phase which has concurrent off-diagonal long-range order and density-wave order which is unusual in a system of hard-core bosons in one dimension. Using the finite-size density-matrix renormalization group method, we obtain the complete phase diagram for this model. © 2014 American Physical Society. Source

Purkayastha A.,International Center for Theoretical science | Subrahmanyam V.,Indian Institute of Technology Kanpur
Annals of Physics | Year: 2015

Entanglement spectrum of finite-size correlated electron systems are investigated using the Gutzwiller projection technique. The product of largest eigenvalue and rank of the block reduced density matrix, which is a measure of distance of the state from the maximally entangled state of the corresponding rank, is seen to characterise the insulator to metal crossover in the state. The fraction of distinct eigenvalues exhibits a 'chaotic' behaviour in the crossover region, and it shows a 'integrable' behaviour at both insulating and metallic ends. The integrated entanglement spectrum obeys conformal field theory (CFT) prediction at the metal and insulator ends, but shows a noticeable deviation from CFT prediction in the crossover regime, thus it can also track a metal-insulator crossover. A modification of the CFT result for the entanglement spectrum for finite size is proposed which holds in the crossover regime also. The adjacent level spacing distribution of unfolded non-zero eigenvalues for intermediate values of Gutzwiller projection parameter g is the same as that of an ensemble of random matrices obtained by replacing each block of reduced density matrix by a random real symmetric Toeplitz matrix. It is strongly peaked at zero, with an exponential tail proportional to e-(n/R)s, where s is the adjacent level spacing, n is number of distinct eigenvalues and R is the rank of the reduced density matrix. © 2015 Elsevier Inc. Source

Singh M.,Indian Institute of Astrophysics | Singh M.,The New School | Dhar A.,Indian Institute of Astrophysics | Mishra T.,International Center for Theoretical science | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

The Mott-insulator-superfluid transition for ultracold bosonic atoms in an optical lattice has been extensively studied in the framework of the Bose-Hubbard model with two-body on-site interactions. In this paper, we analyze the additional effect of the three-body on-site interactions on this phase transition in an optical lattice and the transitions between the various phases that arise in an optical superlattice. Using the mean-field theory and the density matrix renormalization group method, we find the phase diagrams depicting the relationships between various physical quantities in an optical lattice and superlattice. We also propose a possible experimental signature to observe the on-site three-body interactions. © 2012 American Physical Society. Source

Hegde C.,Raman Research Institute | Sabhapandit S.,Raman Research Institute | Dhar A.,International Center for Theoretical science
Physical Review Letters | Year: 2014

We consider a gas of point particles moving in a one-dimensional channel with a hard-core interparticle interaction that prevents particle crossings - this is called single-file motion. Starting from equilibrium initial conditions we observe the motion of a tagged particle. It is well known that if the individual particle dynamics is diffusive, then the tagged particle motion is subdiffusive, while for ballistic particle dynamics, the tagged particle motion is diffusive. Here we compute the exact large deviation function for the tagged particle displacement and show that this is universal, independent of the individual dynamics. © 2014 American Physical Society. Source

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