arXiv subjects

A. Moradpouri

Publications and source records attributed to A. Moradpouri.

4 recordsLinked to original sources

arXiv2025

Quantum Regular Black Holes and Complete Monotonicity

We examine the conjecture for the complete monotonicity of certain curvature invariants for quantum black holes. In this note, we study a class of quantum regular black holes that are static, spherically symmetric, and characterized only by their mass. Additionally, this class of black holes reduces to the Schwarzschild solution in the classical limit $\hbar\to 0$. We provide evidence supporting the non-perturbativity conjecture that perturbative corrections cannot falsify complete monotonicity. We demonstrate that these quantum black holes cannot be generated by perturbative quantum corrections to the Einstein equations. We then investigate the thermodynamics of these black holes and derive a bound on their entropy, showing that the entropy is always greater than the horizon area divided by 4G. We Also demonstrate that these black holes exhibit a bounded temperature, with a maximum temperature scaling as $T\sim\frac{1}{L_p}$ and a critical mass scale where the temperature vanishes

hep-th↗

arXiv2023

Kinetic theory of {\it tilted} Dirac cone materials

We formulate the Boltzmann kinetic equations for interacting tilted Dirac fermions in two space dimensions characterized by a tilt parameter $0\leζ<1$. Solving the linearized Boltzmann equation, we find that the broadening of the Drude pole is enhanced by $κ(ζ)\times(1-ζ^2)^{-1/2}$, where the $κ$ is interaction-induced enhancement factor. The intensity of the Drude pole is also anisotropically enhanced by $(1-ζ^2)^{-1}$. The ubiquitous "redshift" factors $(1-ζ^2)^{1/2}$ can be regarded as a manifestation of an underlying spacetime structure in such solids. The additional broadening $κ$ indicates that interaction effects are more pronounced for electrons in a $ζ$-deformed Minkowski spacetime of tilted Dirac fermions.

cond-mat.str-el↗

arXiv2022

Holographic Hydrodynamics of {\it Tilted} Dirac Materials

We present a gravity dual to a quantum material with tilted Dirac cone in 2+1 dimensional spacetime. In this many-body system the electronics degrees of freedom are strongly-coupled, constitute a Dirac fluid and admit an effective hydrodynamic description. The holographic techniques are applied to compute the thermodynamic variables and hydrodynamic transports of a fluid on the boundary of an asymptotically anti de Sitter spacetime with a boosted black hole in the bulk. We find that these materials exhibit deviations from the normal Dirac fluid which rely on the tilt of the Dirac cone. In particular, the shear viscosity to entropy density ratio is reduced and the KSS bound is violated in this system. This prediction can be experimentally verified in two-dimensional quantum materials ({\it e.g.} organic $α$-({BEDT}-{TTF})$_2$I$_3$ and $8Pmmn$ borophene) with tilted Dirac cone.

hep-th↗

arXiv2022

Electron Currents from Gradual Heating in Tilted Dirac Cone Materials

Materials hosting tilted Dirac/Weyl fermions provide an emergent spacetime structure for the solid state physics. They admit a geometric description in terms of an effective spacetime metric. Using this metric that is rooted in the long-distance behavior of the underlying lattice, we formulate the hydrodynamic theory for tilted Dirac/Weyl materials in $2+1$ spacetime dimensions. We find that the mingling of space and time through the off-diagonal components of the metric gives rise to: (i) heat and electric currents in response to the $temporal$ gradient of temperature, $\partial_t T$ and (ii) a non-zero symmetric Hall-like conductance $σ^{ij}\propto ζ^iζ^j$ where $ζ^j$ parameterize the tilt in $j$'th space direction. The finding (i) above that can be demonstrated in the laboratory in state of the art cooling/heating rate settings, implies that the non-trivial emergent spacetime geometry in these materials empowers them with a fascinating capability to harvest the naturally available sources of $\partial_t T$ of hot deserts to produce electric energy. We further find a tilt-induced contribution to the conductivity which is an offspring of Drude pole and can be experimentally disentangled from the Drude pole itself.

cond-mat.mes-hall↗