arXiv subjects

V. Avramov

Publications and source records attributed to V. Avramov.

4 recordsLinked to original sources

arXiv2024

Complexity of Quantum Harmonic Oscillator in External Magnetic Field

In this paper, we investigate the circuit complexity of a quantum harmonic oscillator subjected to an external magnetic field. Utilizing the Nielsen approach within the thermofield dynamics (TFD) framework, we determine the complexity of thermofield double states as functions of time, temperature, and the external magnetic field. Our subsequent analysis reveals various features of this complexity. For instance, as temperature increases, the amplitude of complexity oscillations also rises, while at low temperatures, complexity stabilizes at a constant positive value. Furthermore, the magnetic field creates two distinct sectors: strong magnetic fields exhibit periodic complexity oscillations, whereas weak magnetic fields induce a beating effect. Finally, we confirm that the rate of complexity obeys the Lloyd bound.

quant-ph↗

arXiv2024

On Thermodynamic Stability of Black Holes. Part II: AdS Family of Solutions

This study is aimed at providing a thorough analysis of the classical thermodynamic stability of black holes within the Anti-de Sitter (AdS) family. We utilize the Nambu bracket formalism to calculate local heat capacities and employ Sylvester's criterion in the mass-energy ensemble to determine both local and global thermodynamic stability regions. Emphasizing the crucial role of the cosmological constant, we establish the conditions necessary for the existence of thermodynamically stable black hole configurations. Our work highlights the applicability of classical thermodynamics in understanding black hole physics, while acknowledging the potential deviations that may impact the observables of the system beyond the classical level.

gr-qc↗

arXiv2023

On Thermodynamic Stability of Black Holes. Part I: Classical Stability

We revisit the classical thermodynamic stability of the standard black hole solutions by implementing the intrinsic necessary and sufficient conditions for stable global and local thermodynamic equilibrium. The criteria for such equilibria are quite generic and well-established in classical thermodynamics, but they have not been fully utilized in black hole physics. We show how weaker or incomplete conditions could lead to misleading or incorrect results for the thermodynamic stability of the system. We also stress the importance of finding all possible local heat capacities in order to fully describe the classical equilibrium picture of black holes. Finally, we thoroughly investigate the critical and phase transition curves and the limits of the classical analysis. This paper is the first in the line of intended works on thermodynamic stability of black holes in modified theories of gravity and holography.

gr-qc↗

arXiv2023

From Heun to Painlevé on Sasaki-Einstein Spaces and Their Confluent Limits

The aim of this paper is to study the effect of isomonodromic deformations of the evolution of scalar fields in Sasaki-Einstein spaces in the context of holography. Here we analyze the monodromy data of the general Heun equation, resulting from a scalar on Y$^{p,q}$, thus obtaining the corresponding Painlevé VI equation. Furthermore we have considered limits leading to a coalescence of singularities, which in turn transform the original Painlevé VI equation, to one of lower rank. The confluent limits we have considered are Y$^{p,p}$, T$^{1,1} / \mathbb{Z}_2$ and Y$^{\infty, q}$.

hep-th↗