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77 - Anindya Biswas 2021
In this paper we study Joule-Thomson $(JT)$ expansion of non-linearly charged $AdS$ black holes in Einstein-power-Yang-Mills (EPYM) gravity in $D$ dimensions. Within the framework of extended phase space thermodynamics we identify the cosmological co nstant as thermodynamic pressure and the black hole mass with the enthalpy and derive the Joule-Thomson coefficient $mu$. Furthermore we have presented equations for inversion curves and the exact expression for the minimum inversion temperature. We also have calculated the ratio between the minimum of inversion $T_i^{min}$ and the critical temperature $T_c$ and obtained the analytic expression for the ratio $frac{T_i^{min}}{T_c}$ that depends explicitly on the non-linearity parameter $q$ and dimension $D$. We consider the isenthalpic curves in the $T- P$ plane for different values of the fixed black hole mass and obtain heating and cooling region. Finally we have dealt with two limiting masses which characterizes the process of Joule-Thomson expansion in the $EPYM$ black holes.
The distribution of entanglement of typical multiparty quantum states is not uniform over the range of the measure utilized for quantifying the entanglement. We intend to find the response of quenched disorder in the state parameters on this non-unif ormity for typical states. We find that the typical entanglement, quenched averaged over the disorder, is taken farther away from uniformity, as quantified by decreased standard deviation, in comparison to the clean case. The feature is seemingly generic, as we see it for Gaussian and non-Gaussian disorder distributions, for varying strengths of the disorder, and for disorder insertions in one and several state parameters. The non-Gaussian distributions considered are uniform and Cauchy-Lorentz. Two- and three-qubit pure state Haar-uniform generations are considered for the typical state productions. We also consider noi
Given a domain $Omega$ in $mathbb{C}^n$ and a collection of test functions $Psi$ on $Omega$, we consider the complex-valued $Psi$-Schur-Agler class associated to the pair $(Omega,,Psi)$. In this article, we characterize interpolating sequences for th e associated Banach algebra of which the $Psi$-Schur-Agler class is the closed unit ball. When $Omega$ is the unit disc $mathbb{D}$ in the complex plane $mathbb{C}$ and the class of test function includes only the identity function on $mathbb{D}$, the aforementioned algebra is the algebra of bounded holomorphic functions on $mathbb{D}$ and in this case, our characterization reduces to the well known result by Carleson. Furthermore, we present several other cases of the pair $(Omega,,Psi)$, where our main result could be applied to characterize interpolating sequences which also show the efficacy of our main result.
We make a connection between the structure of the bidisc and a distinguished subgroup of its automorphism group. The automorphism group of the bidisc, as we know, is of dimension six and acts transitively. We observe that it contains a subgroup that is isomorphic to the automorphism group of the open unit disc and this subgroup partitions the bidisc into a complex curve and a family of strongly pseudo-convex hypersurfaces that are non-spherical as CR-manifolds. Our work reverses this process and shows that any $2$-dimensional Kobayashi-hyperbolic manifold whose automorphism group (which is known, from the general theory, to be a Lie group) has a $3$-dimensional subgroup that is non-solvable (as a Lie group) and that acts on the manifold to produce a collection of orbits possessing essentially the characteristics of the concretely known collection of orbits mentioned above, is biholomorphic to the bidisc. The distinguished subgroup is interesting in its own right. It turns out that if we consider any subdomain of the bidisc that is a union of a proper sub-collection of the collection of orbits mentioned above, then the automorphism group of this subdomain can be expressed very simply in terms of this distinguished subgroup.
We study the action of the automorphism group of the $2$ complex dimensional manifold symmetrized bidisc $mathbb{G}$ on itself. The automorphism group is 3 real dimensional. It foliates $mathbb{G}$ into leaves all of which are 3 real dimensional hype rsurfaces except one, viz., the royal variety. This leads us to investigate Isaevs classification of all Kobayashi-hyperbolic 2 complex dimensional manifolds for which the group of holomorphic automorphisms has real dimension 3 studied by Isaev. Indeed, we produce a biholomorphism between the symmetrized bidisc and the domain [{(z_1,z_2)in mathbb{C} ^2 : 1+|z_1|^2-|z_2|^2>|1+ z_1 ^2 -z_2 ^2|, Im(z_1 (1+overline{z_2}))>0}] in Isaevs list. Isaev calls it $mathcal D_1$. The road to the biholomorphism is paved with various geometric insights about $mathbb{G}$. Several consequences of the biholomorphism follow including two new characterizations of the symmetrized bidisc and several new characterizations of $mathcal D_1$. Among the results on $mathcal D_1$, of particular interest is the fact that $mathcal D_1$ is a symmetrization. When we symmetrize (appropriately defined in the context in the last section) either $Omega_1$ or $mathcal{D}^{(2)}_1$ (Isaevs notation), we get $mathcal D_1$. These two domains $Omega_1$ and $mathcal{D}^{(2)}_1$ are in Isaevs list and he mentioned that these are biholomorphic to $mathbb{D} times mathbb{D}$. We produce explicit biholomorphisms between these domains and $mathbb{D} times mathbb{D}$.
We compute concurrence, a measure of bipartite entanglement, of the first excited state of the $1$-D Heisenberg frustrated $J_1$-$J_2$ spin-chain and observe a sudden change in the entanglement of the eigen state near the coupling strength $alpha=J_2 /J_1approx0.241$, where a quantum phase transition from spin-fluid phase to dimer phase has been previously reported. We numerically observe this phenomena for spin-chain with $8$ sites to $16$ sites, and the value of $alpha$ at which the change in entanglement is observed asymptotically tends to a value $alpha_capprox0.24116$. We have calculated the finite-size scaling exponents for spin chains with even and odd spins. It may be noted that bipartite as well as multipartite entanglement measures applied on the ground state of the system, fail to detect any quantum phase transition from the gapless to the gapped phase in the $1$-D Heisenberg frustrated $J_1$-$J_2$ spin-chain. Furthermore, we measure bipartite entanglement of first excited states for other spin models like $2$-D Heisenberg $J_1$-$J_2$ model and Shastry-Sutherland model and find similar indications of quantum phase transitions.
Given a domain $Omega$ in $mathbb{C}^m$, and a finite set of points $z_1,z_2,ldots, z_nin Omega$ and $w_1,w_2,ldots, w_nin mathbb{D}$ (the open unit disc in the complex plane), the textit{Pick interpolation problem} asks when there is a holomorphic f unction $f:Omega rightarrow overline{mathbb{D}}$ such that $f(z_i)=w_i,1leq ileq n$. Pick gave a condition on the data ${z_i, w_i:1leq ileq n}$ for such an $interpolant$ to exist if $Omega=mathbb{D}$. Nevanlinna characterized all possible functions $f$ that textit{interpolate} the data. We generalize Nevanlinnas result to a domain $Omega$ in $mathbb{C}^m$ admitting holomorphic test functions when the function $f$ comes from the Schur-Agler class and is affiliated with a certain completely positive kernel. The Schur class is a naturally associated Banach algebra of functions with a domain. The success of the theory lies in characterizing the Schur class interpolating functions for three domains - the bidisc, the symmetrized bidisc and the annulus - which are affiliated to given kernels.
Given a domain $Omega$ in $mathbb{C}^m$, and a finite set of points $z_1,ldots, z_nin Omega$ and $w_1,ldots, w_nin mathbb{D}$ (the open unit disc in the complex plane), the $Pick, interpolation, problem$ asks when there is a holomorphic function $f:O mega rightarrow overline{mathbb{D}}$ such that $f(z_i)=w_i,1leq ileq n$. Pick gave a condition on the data ${z_i, w_i:1leq ileq n}$ for such an $interpolant$ to exist if $Omega=mathbb{D}$. Nevanlinna characterized all possible functions $f$ that $interpolate$ the data. We generalize Nevanlinnas result to an arbitrary set $Omega$. In this case, the function $f$ comes from the Schur-Agler class. The abstract result is then applied to three examples - the bidisc, the symmetrized bidisc and the annulus. In these examples, the Schur-Agler class is the same as the Schur class.
151 - Anindya Biswas 2017
In this paper, we have studied the Hawking radiation of massive spin-$1$ particles from the black holes in $(2+1)$ dimensions with non- trivial dilaton fields. We consider two special varities of these black holes one is static charged and other is s pinning electrically neutral. By applying the standard method of $WKB$ approximation and Hamilton- Jacobi ansatz we have shown the tunneling probability and Hawking temperature of massive bosons accordingly. In the certain limit of the dilaton coupling for spinning neutral case we have recovered the Hawking temperature of the $BTZ$ black holes as well.
Fidelity plays an important role in measuring distances between pairs of quantum states, of single as well as multiparty systems. Based on the concept of fidelity, we introduce a physical quantity, shared purity, for arbitrary pure or mixed quantum s tates of shared systems of an arbitrary number of parties in arbitrary dimensions. We find that it is different from quantum correlations. However, we prove that a maximal shared purity between two parties excludes any shared purity of these parties with a third party, thus ensuring its quantum nature. Moreover, we show that all generalized GHZ states are monogamous, while all generalized W states are non-monogamous with respect to this measure. We apply the quantity to investigate the quantum XY spin models, and observe that it can faithfully detect the quantum phase transition present in these models. We perform a finite-size scaling analysis and find the scaling exponent for this quantity.
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