Quantum mechanics is an extremely successful theory that agrees with every experiment. However, the principle of linear superposition, a central tenet theory, apparently contradicts commonplace observation: macroscopic objects are never found in superposition position states. Moreover, does not really explain as to why during quantum measurement, deterministic evolution replaced by probabilistic evolution, whose random outcomes obey Born probability rule. In this article we review...

The inflationary paradigm provides a mechanism to generate the primordial perturbations needed explain observed large-scale structures in Universe. Inflation traces back all inhomogeneities quantum fluctuations although look classical today. squeezing of along with decoherence accounts for many aspects this quantum-to-classical transition, it remains matter debate as whether is sufficient issue realization single outcome (i.e. macro-objectification) from ensemble given that Universe closed...

We perform $\textit{exact}$ half-line path integral quantization of flat, homogeneous cosmological models containing a perfect fluid acting as an internal clock, in $D+1$ dimensional minisuperspace setup. also discuss certain classes operator ordering ambiguity inherent such procedures and argue that particular prescription the quantum theory can preserve two symmetries, namely arbitrary lapse rescalings general covariance, which are already present at classical level. As result this...

An atom serves as a natural probe of quantum field fluctuations and any modifications to them, fundamentally manifested in spontaneous emission. A collection excited atoms can spontaneously develop correlations seeded by the vacuum electromagnetic field. The build over finite time period, culminating an intense, directional emission photons known superradiance. For undergoing uniform linear acceleration, we identify low-acceleration conditions under which buildup occurs faster is driven...

We study gravitational lensing by a recently proposed black hole solution in Loop Quantum Gravity. highlight the fact that quantum gravity corrections to Schwarzschild metric this model evade `mass suppression' effects (that usual are susceptible to) virtue of one parameters being dimensionless, which is unlike any other motivated parameter. Gravitational strong and weak deflection regimes studied sample consistency relation presented could serve as test model. discuss though for...

Black holes, initially thought of as very interesting geometric constructions nature, over time, have learnt to (often) come up with surprises and challenges. From the era being described merely some exotic solutions \gr, they have, in modern times, really started test our confidence everything else, we know about nature. They this process, also earned a dreadsome reputation corners theoretical physics. The most serious charge on black holes is that eat information, never release...

Some of the most prominent theoretical predictions modern times, e.g., Unruh effect, Hawking radiation, and gravity-assisted particle creation, are supported by from fact that various quantum constructs like content vacuum fluctuations a field observer-dependent. Despite being fundamental in nature, these have not yet been experimentally verified because one needs extremely strong gravity (or acceleration) to bring them within existing experimental resolution. In this Letter, we demonstrate...

One of the primary reasons behind difficulty in observing Unruh effect is that for achievable acceleration scales finite temperature effects are significant only low frequency modes field. Since density field falls small frequencies free space, which relevant thermal would be less number to make an observably effect. In this Letter, we investigate response Unruh-DeWitt detector coupled a massless scalar confined long cylindrical cavity. The inside such cavity shows resonance structure, i.e.,...

Models of spontaneous wave function collapse modify the linear Schrödinger equation standard Quantum Mechanics by adding stochastic non-linear terms to it. The aim such models is describe quantum (linear) nature microsystems along with classical (violation superposition principle) macroscopic ones. addition in leads non-conservation energy system under consideration. Thus, a striking feature heat non-relativistic particles constant rate. If process physical, then it has ability perturb...

We discuss several aspects of quantum field theory a scalar in Friedmann universe, clarifying and highlighting conceptual technical issues. (A) show that one can map the dynamics (1) massless universe with power law expansion to (2) massive de Sitter spacetime, which allows us understand features either system clarifies issues related limit. (B) obtain useful integral representation for Euclidean Green's function by relating it solution hypothetical electrostatic problem five dimensions....

It is generally believed that, when matter collapses to form a black hole, the complete information about initial state of cannot be retrieved by future asymptotic observers, through local measurements. This contrary expectation from unitary evolution in quantum theory and leads (a version of) hole paradox. Classically, nothing else, apart mass, charge angular momentum expected revealed such observers after formation hole. Semi-classically, holes evaporate their Hawking radiation. The...

In flat spacetime, the vacuum neutrino flavor oscillations are known to be sensitive only difference between squared masses, and not individual of neutrinos. this work, we show that lensing neutrinos induced by a gravitational source substantially modifies standard picture it gives rise novel contribution through which oscillation probabilities also depend on masses. A gravitating mass located detector deflects in their journey, at detection point, arriving different paths can lead...

The crux of the black hole information paradox is related to fact that complete about initial state a quantum field in collapsing spacetime not available future asymptotic observers, belying expectations from unitary theory. We study imprints contained specific class distortions radiation and identify classes states can be partially or fully reconstructed within. Even for general state, we uncover some information. These results suggest classical collapse scenario ignores this richness...

The state of a quantum system acquires phase factor, called the geometric phase, when taken around closed trajectory in parameter space, which depends only on geometry space. Because its sensitive nature, is instrumental capturing weak effects such as acceleration-induced noninertial field theoretic effects. In this paper, we study response circularly rotating detector inside an electromagnetic cavity. Using cavity, contribution to can be isolated from or strengthened relative inertial...

Abstract We use the Jordan frame–Einstein frame correspondence to explore dual universes with contrasting cosmological evolutions. study mapping between Einstein and frames where universe describes late-time evolution of physical universe, which is driven by dark energy non-relativistic matter. The Brans–Dicke theory gravity considered be scalar–tensor in frame. show that an $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM model,...

Despite numerous proposals investigating various properties of accelerated detectors in different settings, detecting the Unruh effect remains challenging due to typically weak signal at achievable accelerations. For an atom with frequency gap <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>ω</a:mi><a:mn>0</a:mn></a:msub></a:math>, free space, significant acceleration-induced modification like transition rates and radiative energy shifts requires...

Abstract The Bogoliubov transformation connecting the standard inertial frame mode functions to &amp;#xD; defined in Rindler $R_0$, leads result that vacuum appears as a thermal state with temperature $T_0=a_0/2\pi$ where $a_0$ is acceleration parameter of $R_0$. We construct an infinite family nested Rindler-like coordinate systems $R_1, R_2, ...$ within right wedge, time coordinates $\tau_1, \tau_2, ...,$ and parameters $a_1, a_2, by shifting origin along $x$-axis amounts $\ell_1,...

The appearance of the inertial vacuum state in Rindler frame has been extensively studied literature, both from point view QFT developed using foliation and response an Unruh-Dewitt Detector (UDD). In comparison, less attention devoted to study non-vacuum states when viewed frame. We provide a comprehensive this issue paper. first present general formalism describing characterization arbitrary described (i) (ii) UDD moving along trajectory. use explicitly compute results for uniformly...

The quantum genesis of Hawking radiation is a long-standing puzzle in black hole physics. Semi-classically one can argue that the spectrum emitted by look very much sparse unlike what expected from thermal object. It was demonstrated through simple model will retain discrete profile, at least weak energy regime. However, it suggested this discreteness might be an artifact simplicity eigen-spectrum considered. Different theories can, principle, give rise to different complicated spectra and...

We attempt to calculate the point separated Noise Kernel for self similar Tolman Bondi metric, using a method that developed by Eftekharzadeh et. al ultra-static spacetimes referring work Page. In case of formation naked singularity, thus obtained is found be regular except on Cauchy horizon, where it diverges. The behavior noise in covered singularity regular. This result seemingly renders back reaction non-negligible which questions stability results from semiclassical treatment metric.

We study a dynamic version of the Unruh effect in two dimensional collapse model forming black hole. In this two-dimensional scalar field coupled to dilaton gravity, moving leftwards, collapses form There are sets asymptotic ($t\to\infty$) observers, around $x\to\infty$ and $x\to-\infty$. The observers at right null infinity witness thermal flux radiation associated with time dependent geometry leading hole formation its subsequent Hawking evaporation, an expected manner. show that even left...