arXiv subjects

H. E. Camblong

Publications and source records attributed to H. E. Camblong.

11 recordsLinked to original sources

arXiv2026

Acceleration radiation and HBAR thermodynamics for atoms falling into a BTZ black hole: A CQM quantum-optics approach

Atoms falling freely into a Bañados-Teitelboim-Zanelli (BTZ) black hole in a Boulware-like vacuum are shown to emit radiation with a Planck spectrum at the Hawking temperature $T_{H}$. This leads to thermal Hawking-like radiation for a cloud of falling atoms prepared with random initial times. Moreover, the radiation is related to the relative equivalence principle, with the vacuum field modes accelerated with respect to the falling atom. The physics of the atom-field interactions is most easily described within a quantum optics approach, where each atom can be interpreted as a detector. Despite the topological nature of gravity in $(2+1)$ dimensions, the thermodynamic and radiation properties of BTZ black holes are still universally governed by the same near-horizon conformal quantum mechanics (CQM) applicable to higher-dimensional gravity. This universal conformal behavior is exhibited by all fields in the background of generic black holes, and generates an HBAR entropy $S_{\mathcal P}$ associated with the photon radiation field that mimics the Bekenstein-Hawking entropy $S_{\mathrm{BH}}=A/4$, proportional to the black-hole horizon area, and with the correct $1/4$ proportionality factor.

gr-qc↗

arXiv2026

Quantum aspects of spacetime: A quantum optics view of acceleration radiation and black holes

For the centennial of quantum mechanics, we offer an overview of the central role played by quantum information and thermalization in problems involving fundamental properties of spacetime and gravitational physics. This is an open area of research still a century after the initial development of formal quantum mechanics, highlighting the effectiveness of quantum physics in the description of all natural phenomena. These remarkable connections can be highlighted with the tools of modern quantum optics, which effectively addresses the three-fold interplay of interacting atoms, fields, and spacetime backgrounds describing gravitational fields and noninertial systems. In this review article, we select aspects of these phenomena centered on quantum features of the acceleration radiation of particles in the presence of black holes. The ensuing horizon-brightened radiation (HBAR) provides a case study of the role played by quantum physics in nontrivial spacetime behavior, and also shows a fundamental correspondence with black hole thermodynamics.

gr-qc↗

arXiv2025

Conformal quantum mechanics of causal diamonds: Quantum instability and semiclassical approximation

Causal diamonds are known to have thermal behavior that can be probed by finite-lifetime observers equipped with energy-scaled detectors. This thermality can be attributed to the time evolution of observers within the causal diamond, governed by one of the conformal quantum mechanics (CQM) symmetry generators: the noncompact hyperbolic operator $S$. In this paper, we show that the unbounded nature of $S$ endows it with a quantum instability, which is a generalization of a similar property exhibited by the inverted harmonic oscillator potential. Our analysis is semiclassical, including a detailed phase-space study of the classical dynamics of $S$ and its dual operator $R$, and a general semiclassical framework yielding basic instability and thermality properties that play a crucial role in the quantum behavior of the theory. For an observer with a finite lifetime $\mathcal{T}$, the detected temperature $T_D = 2 \hbar/(π\mathcal{T})$ is associated with a Lyapunov exponent $λ_L = πT_D/\hbar$, which is half the upper saturation bound of the information scrambling rate.

quant-ph↗

arXiv2025

Conformal quantum mechanics of causal diamonds: Time evolution, thermality, and instability via path integral functionals

An observer with a finite lifetime $\mathcal{T}$ perceives the Minkowski vacuum as a thermal state at temperature $T_D = 2 \hbar/(π\mathcal{T})$, as a result of being constrained to a double-coned-shaped region known as a causal diamond. In this paper, we explore the emergence of thermality in causal diamonds due to the role played by the symmetries of conformal quantum mechanics (CQM) as a (0+1)-dimensional conformal field theory, within the de Alfaro-Fubini-Furlan model and generalizations. In this context, the hyperbolic operator $S$ of the SO(2,1) symmetry of CQM: (i) is the generator of the time evolution of a diamond observer; (ii) its dynamical behavior leads to the predicted thermal nature; and (iii) its associated quantum instability has a Lyapunov exponent $λ_L = πT_D/\hbar$, which is half the upper saturation bound of the information scrambling rate. Our approach is based on a comprehensive framework of path-integral representations of the CQM generators in canonical and microcanonical forms, supplemented by semiclassical arguments. The properties of the operator $S$ are studied with emphasis on an operator duality with the corresponding elliptic operator $R$, using a representation in terms of an effective scale-invariant inverse square potential combined with inverted and ordinary harmonic oscillator potentials.

quant-ph↗

arXiv2024

Entanglement Degradation in Causal Diamonds

Entanglement degradation appears to be a generic prediction in relativistic quantum information whenever horizons restrict access to a region of spacetime. This property has been previously explored in connection with the Unruh effect, where a bipartite entangled system composed of an inertial observer (Alice) and a uniformly accelerated observer (Rob) was studied, with entanglement degradation caused by the relative acceleration -- and with equivalent results for the case when Alice is freely falling into a black hole and Rob experiences a constant proper acceleration as a stationary near-horizon observer. In this work, we show that a similar degradation also occurs in the case of an entangled system composed of an inertial observer (Alice) and a "diamond observer" (Dave) with a finite lifetime. The condition of a finite lifetime is equivalent to the restriction of Dave's access within a causal diamond. Specifically, if the system starts in a maximally entangled state, prepared from Alice's perspective, entanglement degradation is enforced by the presence of the diamond's causal horizons.

quant-ph↗

arXiv2023

Spectral Properties of the Symmetry Generators of Conformal Quantum Mechanics: A Path-Integral Approach

A path-integral approach is used to study the spectral properties of the generators of the SO(2,1) symmetry of conformal quantum mechanics (CQM). In particular, we consider the CQM version that corresponds to the weak-coupling regime of the inverse square potential. We develop a general framework to characterize a generic symmetry generator $G$ (linear combinations of the Hamiltonian $H$, special conformal operator $K$, and dilation operator $D$), from which the path-integral propagators follow, leading to a complete spectral decomposition. This is done for the three classes of operators: elliptic, parabolic, and hyperbolic. We also highlight novel results for the hyperbolic operators, with a continuous spectrum, and their quantum-mechanical interpretation. The spectral technique developed for the eigensystem of continuous-spectrum operators can be generalized to other operator problems.

quant-ph↗

arXiv2021

Quantum optics meets black hole thermodynamics via conformal quantum mechanics: II. Thermodynamics of acceleration radiation

The thermodynamics of ``horizon brightened acceleration radiation'' (HBAR), due to a random atomic cloud freely falling into a black hole in a Boulware-like vacuum, is shown to mimic the thermodynamics of the black hole itself. The thermodynamic framework is developed in its most general form via a quantum optics master equation, including rotating (Kerr) black holes and for any set of initial conditions of the atomic cloud. The HBAR field exhibits thermal behavior at the Hawking temperature and an area-entropy-flux relation that resembles the Bekenstein-Hawking entropy. In addition, this general approach reveals:(i) the existence of an HBAR-black-hole thermodynamic correspondence that explains the HBAR area-entropy-flux relation;(ii) the origin of the field entropy from the near-horizon behavior, via conformal quantum mechanics (CQM).

gr-qc↗

arXiv2021

Quantum optics meets black hole thermodynamics via conformal quantum mechanics: I. Master equation for acceleration radiation

A quantum-optics approach is used to study the nature of the acceleration radiation due to a random atomic cloud falling freely into a generalized Schwarzschild black hole through a Boulware vacuum. The properties of this horizon brightened acceleration radiation (HBAR) are analyzed with a master equation that is fully developed in a multimode format. A scheme for the coarse-graining average for an atomic cloud is considered, with emphasis on the random injection scenario, which is shown to generate a thermal state. The role played by conformal quantum mechanics (CQM) is shown to be critical for detailed balance via a Boltzmann factor governed by the near-horizon physics, with the unique selection of the Hawking temperature. The HBAR thermal state is the basis for a thermodynamic framework that parallels black hole thermodynamics.

gr-qc↗

arXiv2021

Acceleration radiation of an atom freely falling into a Kerr black hole and near-horizon conformal quantum mechanics

An atom falling freely into a Kerr black hole in a Boulware-like vacuum is shown to emit radiation with a Planck spectrum at the Hawking temperature. For a cloud of falling atoms with random initial times, the radiation is thermal. The existence of this radiation is due to the acceleration of the vacuum field modes with respect to the falling atom. Its properties can be traced to the dominant role of conformal quantum mechanics (CQM) in the neighborhood of the event horizon. We display this effect for a scalar field, though the acceleration radiation has a universal conformal behavior that is exhibited by all fields in the background of generic black holes.

gr-qc↗

arXiv2020

Near-horizon aspects of acceleration radiation by free fall of an atom into a black hole

A two-level atom freely falling towards a Schwarzschild black hole was recently shown to detect radiation in the Boulware vacuum in an insightful paper [M. O. Scully et al., Proc. Natl. Acad. Sci. U.S.A. 115, 8131 (2018)]. The two-state atom acts as a dipole detector and its interaction with the field can be modeled using a quantum optics approach. The relative acceleration between the scalar field and the detector causes the atom to detect the radiation. In this paper, we show that this acceleration radiation is driven by the near-horizon physics of the black hole. This insight reinforces the relevance of near-horizon conformal quantum mechanics for all the physics associated with the thermodynamic properties of the black hole. We additionally highlight the conformal aspects of the radiation that is given by a Planck distribution with the Hawking temperature.

gr-qc↗

arXiv2019

Spectral density, Levinson's theorem, and the extra term in the second virial coefficient for 1D delta-function potential

In contrast with the 3D result, the Beth-Uhlenbeck (BU) formula in 1D contains an extra -1/2 term. The origin of this -1/2 term is explained using a spectral density approach. To be explicit, a delta-function potential is used to show that the correction term arises from a pole of the density of states at zero energy. The spectral density method shows that this term is actually an artifact of the non-normalizability of the scattering states and an infrared cutoff regularization scheme has to be used to get the correct result in 1D. The formal derivation of the BU formula would miss this term since it ignores the effects of the boundary terms. While the result is shown for the delta-function potential, the method and result are valid for more general potentials. Additionally, the 1D Levinson's theorem can be extracted from the spectral density method using the asymptotic form of general potentials. The importance of the result lies in the fact that all these correction terms in 1D have a universal source: a pole at zero energy. Similar calculations using quantum field theoretical approaches (without explicit infrared cutoff regularization schemes) also show the same subtleties with the correction term originating from the zero energy scattering states (appendix A).

cond-mat.quant-gas↗