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Matthew P. G. Robbins

Publications and source records attributed to Matthew P. G. Robbins.

8 recordsLinked to original sources
arXiv2023

Signatures of Rotating Black Holes in Quantum Superposition

A new approach for operationally studying the effects of spacetime in quantum superpositions of semiclassical states has recently been proposed by some of the authors. This approach was applied to the case of a (2+1)-dimensional Bañados-Teitelboim-Zanelli (BTZ) black hole in a superposition of masses, where it was shown that a two-level system interacting with a quantum field residing in the spacetime exhibits resonant peaks in its response at certain values of the superposed masses. Here, we extend this analysis to a mass-superposed rotating BTZ black hole, considering the case where the two-level system co-rotates with the black hole in a superposition of trajectories. We find similar resonances in the detector response function at rational ratios of the superposed outer horizon radii, specifically in the case where the ratio of the inner and outer horizons is fixed. This suggests a connection with Bekenstein's seminal conjecture concerning the discrete horizon spectra of black holes in quantum gravity, generalized to the case of rotating black holes. Our results suggest that deeper insights into quantum-gravitational phenomena may be accessible via tools in relativistic quantum information and curved spacetime quantum field theory.

gr-qc↗
arXiv2021

Anti-Hawking Phenomena around a Rotating BTZ Black Hole

In both flat and curved spacetimes, there are weak and strong versions of the anti-Unruh/anti-Hawking effects, in which the KMS field temperature is anti-correlated with the response of a detector and its inferred temperature. We investigate for the first time the effects on the weak and strong anti-Hawking effects for an Unruh-DeWitt detector orbiting a BTZ black hole in the co-rotating frame. We find that rotation can significantly amplify the strength of the weak anti-Hawking effect, whereas it can either amplify or reduce the strength of the strong anti-Hawking effect depending on boundary conditions. For the strong anti-Hawking effect, we find a non-monotonic relationship between the angular momentum and detector temperature for each boundary condition. In addition, we note that the weak anti-Hawking effect is independent of a changing AdS length, while a longer AdS length increases the temperature range of the strong anti-Hawking effect.

gr-qc↗
arXiv2021

Detection of Gravitational Waves using Parametric Resonance in Bose-Einstein Condensates

An interesting proposal for detecting gravitational waves involves quantum metrology of Bose-Einstein condensates (BECs). We consider a forced modulation of the BEC trap, whose frequency matches that of an incoming continuous gravitational wave. The trap modulation induces parametric resonance in the BEC, which in turn enhances sensitivity of the BEC to gravitational waves. We find that such a BEC detector could potentially be used to detect gravitational waves across several orders of magnitude in frequency, with the sensitivity depending on the speed of sound, size of the condensate, and frequency of the phonons. We outline a possible BEC experiment and discuss the current technological limitations. We also comment on the potential noise sources as well as what is necessary for such a detector to become feasible.

gr-qc↗
arXiv2020

Entanglement Amplification from Rotating Black Holes

The quantum vacuum has long been known to be characterized by field correlations between spacetime points. These correlations can be swapped with a pair of particle detectors, modelled as simple two-level quantum systems (Unruh-DeWitt detectors) via a process known as entanglement harvesting. We study this phenomenon in the presence of a rotating BTZ black hole, and find that rotation can significantly amplify the harvested vacuum entanglement. Concurrence between co-rotating detectors is amplified by as much as an order of magnitude at intermediate distances from the black hole relative to that at large distances. The effect is most pronounced for near-extremal small mass black holes, and allows for harvesting at large spacelike detector separations. We also find that the entanglement shadow -- a region near the black hole from which entanglement cannot be extracted -- is diminished in size as the black hole's angular momentum increases.

hep-th↗
arXiv2019

Bose-Einstein Condensates as Gravitational Wave Detectors

We investigate a Bose-Einstein condensate (BEC) as a gravitational wave detector, and study its sensitivity by optimizing the properties of the condensate and the measurement duration. We show that detecting kilohertz gravitational waves is limited by current experimental techniques in squeezing BEC phonons. Future improvements in technology to squeeze BEC states can make them competitive detectors for gravitational waves of astrophysical and/or cosmological origin.

quant-ph↗
arXiv2018

Can Star Products be Augmented by Classical Physics?

It has been suggested that star products in phase-space quantization may be augmented to describe additional, classical effects. That proposal is examined critically here. Two known star products that introduce classical effects are: the generalized Husimi product of coarse-grained quantization, and a non-Hermitian damped star product for the harmonic oscillator. Following these examples, we consider products related by transition differential operators to the classic Moyal star product. We restrict to Hermitian star products, avoiding problems already pointed out for the original damped product. It is shown, however, that with such star products, augmented quantization is impossible, since an appropriate classical limit does not result. For a more complete study, we then also consider generalized, or local, transition operators, that depend on the local phase-space coordinates, as well as their derivatives. In this framework, one example of possible physical interest is constructed. Because of its limited validity and complicated form, however, it cannot be concluded that augmented quantization with local transition operators is practical.

quant-ph↗
arXiv2017

Gravitation as a source of decoherence

It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including ultra-relativistic and non-relativistic particles, at low and high temperatures in an expanding Universe, and show that this proposal is valid for a large class of quantum systems.

gr-qc↗