arXiv subjects

T. Rick Perche

Publications and source records attributed to T. Rick Perche.

At least 37 records · Page 2Linked to original sources

arXiv2024

Localized non-relativistic quantum systems in curved spacetimes: a general characterization of particle detector models

In this manuscript we provide a consistent way of describing a localized non-relativistic quantum system undergoing a timelike trajectory in a background curved spacetime. Namely, using Fermi normal coordinates, we identify an inner product and canonically conjugate position and momentum operators defined in the rest space of the trajectory for each value of its proper time. This framework then naturally provides a recipe for mapping a quantum theory defined in a non-relativistic background to a theory around a timelike trajectory in curved spacetimes. This is done by reinterpreting the position and momentum operators and by introducing a local redshift factor to the Hamiltonian, which gives rise to new dynamics due to the curvature of spacetime and the acceleration of the trajectory. We then apply our formalism to particle detector models, that is, to the case where the non-relativistic quantum system is coupled to a quantum field in a curved background. This allows one to write a general definition for particle detector models which is able to recover the previous models in the literature. Our framework also allows one to estimate the regime of validity of these models, characterizing the situations where particle detectors can be used to accurately probe quantum fields.

quant-ph↗

arXiv2024

Particle Detectors from Localized Quantum Field Theories

We present a fully relativistic model for localized probes in quantum field theory. Furthermore, we show that it is possible to obtain particle detector models from localized quantum field theories that interact with a free quantum field. In particular, a particle detector model is obtained when one traces out over inaccessible degrees of freedom of the localized field. This gives rise to a particle detector model, that is, a quantum degree of freedom that couples to a free field theory in an extended region of spacetime. Moreover, we show that the predictions of traditional particle detector models and fully relativistic localized fields completely coincide to leading order in perturbation theory.

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arXiv2024

Fully Relativistic Entanglement Harvesting

We study the protocol of entanglement harvesting when the particle detectors that harvest entanglement from the field are replaced by fully relativistic quantum field theories. We show that two localized modes of the quantum field theories are able to harvest the same amount of leading order entanglement as two non-relativistic particle detectors, thus implying that QFT probes can generally harvest more entanglement than particle detectors. These results legitimize the use of particle detectors to study entanglement harvesting regardless of their internally non-relativistic nature.

quant-ph↗

arXiv2023

Harvesting entanglement from the gravitational vacuum

We study how quantum systems can harvest entanglement from the quantum degrees of freedom of the gravitational field. Concretely, we describe in detail the interaction of non-relativistic quantum systems with linearized quantum gravity, and explore how two spacelike separated probes can harvest entanglement from the gravitational field in this context. We provide estimates for the harvested entanglement for realistic probes which can be experimentally relevant in the future, since entanglement harvesting experiments can provide evidence for the existence of quantum degrees of freedom of gravity.

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arXiv2023

What gravity mediated entanglement can really tell us about quantum gravity

We revisit the Bose-Marletto-Vedral (BMV) table-top experimental proposal - which aims to witness quantum gravity using gravity mediated entanglement - analyzing the role of locality in the experiment. We first carry out a fully quantum modelling of the interaction of matter and gravity and then show in what way gravity mediated entanglement in the BMV experiment could be accounted for without appealing to quantum degrees of freedom of the gravitational field. We discuss what assumptions are needed in order to interpret the current BMV experiment proposals as a proof of quantum gravity, and also identify the modifications that a BMV-like experiment could have in order to serve as proof of quantum gravity without having to assume the existence of a local mediators in the gravitational field.

quant-ph↗

arXiv2023

The role of quantum degrees of freedom of relativistic fields in quantum information protocols

We analyze the differences between relativistic fields with or without quantum degrees of freedom in relativistic quantum information protocols. We classify the regimes where the existence of quantum degrees of freedom is necessary to explain the phenomenology of interacting quantum systems. We also identify the precise regimes where quantum fields can be well approximated by quantum-controlled classical fields in relativistic quantum information protocols. Our results can be useful to discern which features are fundamentally different in classical and quantum field theory.

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arXiv2023

Duality between amplitude and derivative coupled particle detectors in the limit of large energy gaps

We present a duality between a particle detector model coupled to the amplitude of a scalar field and coupled to the field's derivative in the limit of large energy gaps. We show that the results of the models can be mapped to each other in a one-to-one fashion modulo a rescaling by the detector's gap. Our analysis is valid for arbitrary scalar fields in curved spacetimes, and requires minimal assumptions regarding the detectors. The duality also applies to the case where more than one detector is coupled to the field. This shows that many examples of entanglement harvesting with amplitude coupled UDW detectors give exactly the same result as derivative coupled detectors that interact with the field in the same region of spacetime.

quant-ph↗

arXiv2023

Migrating Carrollian particles on magnetized black hole horizons

By considering a misaligned (asymptotically uniform) magnetic field in the background of a rotating black hole, we uncover a possibility for a highly non-trivial motion of Carrollian particles on the black hole horizon that is characterized by a time-dependent velocity field and reminds us (because of its latitudinal oscillations) of a 'monarch butterfly migration'.

gr-qc↗

arXiv2023

Carrollian Motion in Magnetized Black Hole Horizons

We revisit the motion of massless particles with anyonic spin in the horizon of Kerr--Newman geometry. As recently shown, such particles can move within the horizon of the black hole due to the coupling of charges associated with a 2-parametric central extension of the 2-dimensional Carroll group to the magnetic field generated by the black hole -- the so called "anyonic spin-Hall effect". We show that the previously computed magnetic field is not invariant under Carroll diffeomorphisms and find another result which respects these symmetries of the horizon. We also consider a more astrophysically relevant case of a (weakly charged) rotating back hole placed in a uniform magnetic field, which could, for instance, be induced by the surrounding plasma. We show that a qualitatively similar magnetic field assisted anyonic spin-Hall effect takes place, even in the absence of black hole rotation. The theoretical possibility of a motion induced by a magnetic monopole is also studied.

gr-qc↗

arXiv2022

The geometry of spacetime from quantum measurements

We provide a setup by which one can recover the geometry of spacetime from local measurements of quantum particle detectors coupled to a quantum field. Concretely, we show how one can recover the field's correlation function from measurements on the detectors. Then, we are able to recover the invariant spacetime interval from the measurement outcomes, and hence reconstruct a notion of spacetime metric. This suggest that quantum particle detectors are the experimentally accessible devices that could replace the classical 'rulers' and 'clocks' of general relativity.

quant-ph↗

arXiv2022

Entanglement harvesting: detector gap and field mass optimization

We investigate the protocol of entanglement harvesting, where two spacelike separated particle detectors extract quantum correlations from a quantum field. Specifically, we analyze the role of the mass of the field and the energy gap of the detectors in the protocol. Perhaps surprisingly, we find that there are regimes in which the entanglement harvested can increase with the mass of the field by decreasing the noise experienced by the detectors. Finally, we study the optimal relationship between the gap of the detectors and the other parameters of the setting that maximizes the entanglement harvested, showing that a small mass can improve the protocol even in this case.

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arXiv2022

Spacetime curvature from ultra rapid measurements of quantum fields

We write the curvature of spacetime in terms of the excitation probability of particle detectors ultra-rapidly coupled to a quantum field. More precisely, we provide an expansion for the excitation probability of a smeared UDW detector delta-coupled to a real scalar quantum field in a curved background. Using a short distance expansion for the Wightman function, we express the excitation probability of a detector as the transition probability in Minkowski spacetime plus correction terms written as a function of the curvature tensors and the detector size. Comparing the excitation probability in curved spacetimes with its flat analog, we are able to express the components of the Ricci and Riemann curvature tensors as a function of physically measurable excitation probabilities of different shaped detectors.

quant-ph↗

arXiv2022

A Wavefunction Description for a Localized Quantum Particle in Curved Spacetimes

We reduce Dirac's spinor formalism for a spin 1/2 particle to a complex wavefunction description in curved spacetimes. We consider a localized fermionic particle in curved spacetimes and perform an expansion in terms of the acceleration and curvature around the center of mass of the system, generalizing the results of [Phys. Rev. D 22, 1922]. Under a non-relativistic approximation, one obtains a quantum description in a Hilbert space of complex wavefunctions defined in the rest space of the system. The wavefunction of the particle then evolves according to a modified Schrödinger equation associated with a symmetric Hamiltonian. When compared to the standard Schrödinger equation for a wavefunction, we obtain corrections in terms of the acceleration of the system's center of mass and curvature of spacetime along its trajectory. In summary, we provide a formalism for the use of a complex wavefunction to describe a localized quantum particle in curved spacetimes.

gr-qc↗

arXiv2022

Harvesting entanglement from complex scalar and fermionic fields with linearly coupled particle detectors

We explore entanglement harvesting with particle detectors that couple linearly to non-Hermitian fields. Specifically, we analyze the case of particle detectors coupled to a complex scalar quantum field and to a spin 1/2 fermionic field. We find that the complex scalar model can be a good approximation for the fermionic model in the protocol of entanglement harvesting when the mass of the field is sufficiently large compared to the inverse interaction time. Moreover, we show that by taking advantage of the U(1) degree of freedom of a complex detector it is possible to increase the harvested negativity by up to two orders of magnitude when compared to the case of a real detector.

quant-ph↗

arXiv2022

An angular momentum based graviton detector

We show that gravitons with energy $E<Ω$, where $Ω$ is the energy gap a localized non-relativistic system, can be detected by finite-time interactions with a detector. Our detector is based on a quadrupole moment interaction between the hydrogen atom and the gravitational field in the linearized approximation. In this model, the external agent responsible for switching the interaction on an off inputs energy into the system, which creates a non-zero excitation probability even when the field is in the vacuum state. However, when the gravitational field is in a one-particle state with angular momentum, we obtain excitations due to the field's particle content. These detector excitations are then associated with the detection of gravitons. We also discuss a possible physical realization of our model where the electromagnetic field plays the role of the external agent.

gr-qc↗

arXiv2021

Anti-particle detector models in QFT

We analyze families of particle detector models that linearly couple to different kinds of fermionic and bosonic fields. We also study the response of these detectors to particle and anti-particle excitations of the field. We propose a simple linear complex scalar particle detector model that captures the fundamental features of fermionic field detectors similarly to how the Unruh-DeWitt model captures the features of the light matter interaction. We also discuss why we do not need to limit ourselves to quadratic models commonly employed in past literature. Namely, we provide a physically motivated mechanism that restores U(1) symmetry in these linear complex models.

quant-ph↗

arXiv2021

General features of the thermalization of particle detectors and the Unruh effect

We study the thermalization of smeared particle detectors that couple locally to $any$ operator in a quantum field theory in curved spacetimes. We show that if the field state satisfies the KMS condition with inverse temperature $β$ with respect to the detector's local notion of time evolution, reasonable assumptions ensure that the probe thermalizes to the temperature $1/β$ in the limit of long interaction times. Our method also imposes bounds on the size of the system with respect to its proper acceleration and spacetime curvature in order to accurately probe the KMS temperature of the field. We then apply this formalism to a uniformly accelerated detector probing the Minkowski vacuum of any CPT symmetric quantum field theory, and show that the detector thermalizes to the Unruh temperature, independently of the operator it couples to. This exemplifies yet again the robustness of the Unruh effect, even when arbitrary smeared detectors are used to probe general operators in a quantum field theory.

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arXiv2021

A path integral formulation for particle detectors: the Unruh-DeWitt model as a line defect

Particle detectors are an ubiquitous tool for probing quantum fields in the context of relativistic quantum information (RQI). We formulate the Unruh-DeWitt (UDW) particle detector model in terms of the path integral formalism. The formulation is able to recover the results of the model in general globally hyperbolic spacetimes and for arbitrary detector trajectories. Integrating out the detector's degrees of freedom yields a line defect that allows one to express the transition probability in terms of Feynman diagrams. Inspired by the light-matter interaction, we propose a gauge invariant detector model whose associated line defect is related to the derivative of a Wilson line. This is another instance where nonlocal operators in gauge theories can be interpreted as physical probes for quantum fields.

hep-th↗