arXiv subjects

Jiatong Yan

Publications and source records attributed to Jiatong Yan.

5 recordsLinked to original sources

arXiv2026

Four-Fermion Condensates in Curved Spacetimes: A Functional Approach

Four-fermion interactions appear in effective descriptions of particle physics, many-body systems, and gravitational theories with fermions. Although the same local operator may enter perturbative scattering, a vacuum Nambu-Jona-Lasinio (NJL) instability, or finite-density Bardeen-Cooper-Schrieffer (BCS) pairing, these regimes are distinguished by their interaction channels, quadratic kernels, and quantum states. We give a pedagogical functional account of these distinctions and compute the local one-loop contribution of a scalar-channel NJL mean field to the energy-momentum tensor in curved spacetime. We first display the state data in the in-out functional and construct the closed-time-path functional required for an in-in expectation value. For the NJL saddle, a Hubbard-Stratonovich field shifts the fermion mass, and the parity-even Dirac determinant generates local volume, curvature, and curvature-squared operators. We find the covariant quantum effective action before specializing to a spatially flat FLRW background and derive the corresponding energy density and pressure. The constant-condensate limit agrees with the direct flat-space mean-field calculation. We also explain which additional state and channel data are required for finite-density BCS pairing and comment on renormalization conditions in curved spacetimes.

hep-th↗

arXiv2024

Influence of field mass and acceleration on entanglement generation

We explore the entanglement dynamics of two detectors undergoing uniform acceleration and circular motion within a massive scalar field, while also investigating the influence of the anti-Unruh effect on entanglement harvesting. Contrary to the conventional understanding of the weak anti-Unruh effect, where entanglement typically increases, we observe that the maximum entanglement between detectors does not exhibit a strict monotonic dependence on detector acceleration. Particularly at low accelerations, fluctuations in the entanglement maxima show a strong correlation with fluctuations in detector transition rates.We also find that the maximum entanglement of detectors tends to increase with smaller field mass. Novelly, our findings indicate the absence of a strong anti-Unruh effect in (3+1)-dimensional massive scalar fields. Instead, thermal effects arising from acceleration contribute to a decrease in the detector entanglement maximum.

hep-th↗

arXiv2023

Reveal the lost entanglement for accelerated atoms in the high-dimensional spacetime

When atoms are accelerated in the vacuum, entanglement among atoms will degrade compared with the initial situation before the acceleration. In this paper, we propose a novel and interesting view that the lost entanglement can be recovered completely when the high-dimensional spacetime is exploited, in the case that the acceleration is not too large, since the entanglement loss rate caused by the large acceleration is faster than the recovery process. We also calculate the entanglement change caused by the anti-Unruh effect and found that the lost entanglement could just be recovered part by the anti-Unruh effect, and the anti-Unruh effect could only appear for a finite range of acceleration when interaction time scale is approximately shorter than the reciprocal of the energy gap in two dimensional spacetime. The limit case of zero acceleration is also investigated, which gives an analytical interpretation for the increase or recovery of entanglement.

hep-th↗

arXiv2023

Influence of gravitational waves on quantum multibody states

Based on the freely-falling Unruh-Dewitt model, we study the influence of gravitational waves on the quantum multibody states, i.e. the twin-Fock (TF) state and the mixture of Dicke states. The amount of entanglement of quantum many-body states decreases first and then increases with increasing frequency of gravitational waves. In particular, for some fixed frequencies of gravitational waves, entanglement will increase with the increasing amplitude of gravitational waves, which is different from the usual thought of gravity-induced decoherence and could provide a novel understanding for the quantum property of gravitational waves.

hep-th↗

arXiv2022

Effect of spacetime dimensions on quantum entanglement between two uniformly accelerated atoms

We investigate the entanglement dynamics for a quantum system composed of two uniformly accelerated Unruh-DeWitt detectors in different spacetime dimensions. It is found that the range of parameters in which entanglement can be generated is expanded but the amount of generated entanglement is decreased with the increasing spacetime dimension, by calculating the evolution of two-atom states using the method for open quantum systems. We study the entanglement evolution between two accelerated atoms for different initial two-atom states, and the influence of corresponding spacetime dimensions for every initial state is discussed. When the spacetime dimensions increase, the change of entanglement becomes slower with time. The influence of spacetime dimensions on the change of entanglement also expands to the case of the massive field. The time delay for entanglement generation is shown in different spacetime dimensions. In particular, entanglement decreases more quickly with the increasing spacetime dimensions compared with that in the case of the massless field. The recent found anti-Unruh effect is discussed, and a novel and interesting phenomenon is found that the Unruh effect in small spacetime dimensions can become the anti-Unruh effect in large spacetime dimensions with the same parameters.

gr-qc↗