arXiv subjects

Pradeep Kumar Kumawat

Publications and source records attributed to Pradeep Kumar Kumawat.

3 recordsLinked to original sources

arXiv2026

Detector's response to coherent Rindler and Minkowski photons

We observe that the transition probability in a static two-level quantum detector interacting with a coherent Rindler field mode differs from that of the Rindler detector interacting with a coherent Minkowski field mode. The situation does not change in the quantum detector's response in the semiclassical limit of the field state. This we investigate in $(1+1)$ and $(3+1)$-spacetime dimensions. Interestingly, in $(1+1)$-dimensions, the transition probabilities of the ``classical'' detector in the semiclassical limit of the field state for these two scenarios appear to be identical when the field mode and detector frequencies are taken to be the same. However, in $(3+1)$ dimensions, the detector transition probabilities calculated under the large-acceleration condition do not exhibit such a signature. The implications of these observations are also discussed.

quant-ph↗

arXiv2025

Timelike transitions in an atom by a mirror in light cone and Kruskal-Szekeres regions: a status of quantum equivalence

We investigate the timelike transitions in a two-level atom in the presence of an infinite reflecting mirror in the future-past light cone regions of a Minkowski spacetime, as well as in the region interior of a $(1+1)$ dimensional Schwarzschild black hole. In particular, when considering the light cone regions, two specific scenarios are dealt with -- $(i)$ a mirror is static in Minkowski spacetime while the atom is attached to a frame confined inside the future light cone region, $(ii)$ an atom is static in Minkowski spacetime, and the mirror is confined inside the future light cone region. For both situations, the atom is interacting with field modes defined in the mirror's frame. Analogous configurations are considered in the black hole spacetime: in one case, the mirror carries field modes represented by the Kruskal time, while the atom follows the Schwarzschild time defined inside the black hole; in the other case, the situations are reversed. The analyses, depending on the frame of the atom, are respectively done within the light cone, Minkowski, Schwarzschild, and Kruskal time-interaction pictures. In all of these scenarios, we observe that the excitation probabilities contain a thermal factor and depend periodically on the separation between the atom and the mirror. At the level of transition probabilities, the aforesaid two scenarios in $(1+1)$ dimensional Minkowski-light cone regions appear to be the same for the equal field and atomic frequencies. However, the same is not true when we consider the $(3+1)$ dimensional Minkowski-light cone or the Schwarzschild interior regions. We also estimate the de-excitation probabilities and encounter similar situations. However, we observe that the excitation to de-excitation ratios (EDRs) corresponding to analogous scenarios are equal for equal atomic and field frequencies.

gr-qc↗

arXiv2025

Equivalence in virtual transitions between uniformly accelerated and static atoms: from a bird's eye

We study the prospect of the equivalence principle at the quantum regime by investigating the transition probabilities of a two-level atomic detector in different scenarios. In particular, two specific set-ups are considered. ($i$) $Without~a~boundary$: In one scenario the atom is in uniform acceleration and interacting with Minkowski field modes. While in the other the atom is static and in interaction with Rindler field modes. ($ii$) $With~a~reflecting~boundary$: In one scenario, the atom is uniformly accelerated, and the mirror is static, and in the other scenario, the atom is static, and the mirror is in uniform acceleration. In these cases, the atom interacts with the field modes, defined in the mirror's frame. For both the set-ups, the focus is on the excitation and de-excitation probabilities in $(1+1)$ and $(3+1)$ spacetime dimensions. Our observations affirm that in $(1+1)$ dimensions, for both set-ups the transition probabilities from different scenarios become the same when the atomic and the field frequencies are equal. In contrast, in $(3+1)$ dimensions this equivalence is not observed in general, inspiring us to look for a deeper physical interpretation. Our findings suggest that when the equivalence between different scenarios is concerned, the excitation to de-excitation ratio provides a more consistent measure even in $(3+1)$ dimensions. We discuss the physical interpretation and implications of our findings.

gr-qc↗