scholarly journals Radiative Processes of Two Accelerated Entangled Atoms Near Boundaries

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1515
Author(s):  
Chi Zhang ◽  
Wenting Zhou
Keyword(s):  
Transition Rate ◽  
Radiative Properties ◽  
Entangled State ◽  
Thermal Bath ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Inertial Motion ◽  
Radiative Processes ◽  
Atom System ◽  
Interatomic Energy

By considering the interaction between a two-atom system and the vacuum massless scalar field in the viewpoint of an instantaneously inertial observer, we study the rates of transition of a uniformly accelerated two-atom system in the symmetric/antisymmetric entangled state near a reflecting boundary and in a cavity, respectively. We find that both the downward transition | ψ ± ⟩ → | g A g B ⟩ and the upward transition | ψ ± ⟩ → | e A e B ⟩ occur for the accelerated two-atom system, as in sharp contrast with the case of a static two-atom system, in which the upward transition can never happen. Similar to the rates of transition of atoms immersed in a thermal bath with the FDU temperature, both the downward transition rate and the upward transition rate are characterized by the Plank factor ( e 2 π ω 0 / a − 1 ) − 1 . This character of the transition rates is very different from the other radiative properties of the accelerated two-atom system, such as the resonance interatomic energy, for which the revisions of the effects of uniform acceleration are never characterized by such a factor. We show with analytical and numerical results that both the downward transition and the upward transition processes can be effectively manipulated by the atomic non-inertial motion and by the presence of boundaries. By comparing the upward transition rate with the downward transition rate, we discover that, when ω 0 ≫ a , with ω 0 and a being the energy space and the proper acceleration of the two-atom system, the disentanglement caused by the upward transition is negligible, while, if ω 0 ≪ a , the disentanglement caused by the upward transition becomes as important as that caused by the downward transition.

Geometric phase for a two-level atom immersed in a thermal bath in the global monopole space–time

2019 ◽  
Vol 34 (03n04) ◽  
pp. 1950023 ◽  
Author(s):  
Zhi Wang ◽  
Huabing Cai ◽  
Chang Xu
Keyword(s):  
Geometric Phase ◽  
Thermal Environment ◽  
Open Quantum Systems ◽  
Thermal Fluctuation ◽  
Space Time ◽  
Thermal Bath ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Global Monopole ◽  
Level Atom

In the framework of open quantum systems, and combining with the quantum field theory in curved space–time, we study the geometric phase for a static two-level atom immersed in a thermal bath of a massless scalar field in the background of global monopole space–time. We show that the correction to geometric phase of the atom results from combined effects of both thermal radiation of the thermal bath at finite temperature and the topological property of global monopole. We also discuss the modified geometric phases for this two-level atom purely due to thermal fluctuation of the thermal bath at an effective temperature in Minkowski space–time and also purely resulting from the effect of global monopole space–time. In addition, the numerical results of correction to the geometric phase induced by the effects of thermal environment and the global monopole is presented and discussed. It is clearly seen that the corrections depend crucially on the temperature T of environment and the position r of the atom relative to the global monopole.

scholarly journals Retarded resonance Casimir–Polder interaction of a uniformly rotating two-atom system

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Saptarshi Saha ◽  
Chiranjeeb Singha ◽  
Arpan Chatterjee
Keyword(s):  
Scalar Field ◽  
Vector Fields ◽  
Energy Shift ◽  
Polarization Transfer ◽  
Quantum Master Equation ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Quantum Fields ◽  
Centripetal Acceleration ◽  
Atom System

AbstractWe consider a two-atom system uniformly moving through a circular ring at an ultra-relativistic speed and weakly interacting with the common quantum fields. Two kinds of fields are introduced here: a massive free scalar field and electromagnetic (EM) vector fields. The vacuum fluctuations of the quantum fields give rise to the resonance Casimir–Polder interaction (RCPI) in the system. Using the quantum master equation formalism, we calculate the second-order energy shift of the entangled states of the system. We find two major aspects of RCPI in a circular trajectory. The first one is the presence of the centripetal acceleration, which gives rise to non-thermality in the system, and secondly, due to the interaction with the above fields, the energy shift for RCPI is retarded in comparison with the massless scalar field. The retardation effect can die out by decreasing the centripetal acceleration and increasing the Zeeman frequency of the atoms. We also show that this phenomenon can be observed via the polarization transfer technique. The coherence time for the polarization transfer is calculated, which is different for the different fields.

Quantum Fisher information in massless scalar field with a boundary

2020 ◽  
Vol 34 (29) ◽  
pp. 2050278
Author(s):  
Zhiming Huang
Keyword(s):  
Scalar Field ◽  
Fisher Information ◽  
Quantum Fisher Information ◽  
Thermal Bath ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Vacuum Fluctuation ◽  
Efficient Control ◽  
Estimation Precision ◽  
Time Boundary

We explore the changes of Quantum Fisher information (QFI) for an uniformly accelerating atom coupling to fluctuating massless scalar field with a perfectly reflecting boundary. We first deduce the master equation that the system obeys. For the unbounded case, the vacuum fluctuation and Unruh thermal bath can rapidly degrade the QFI. However, with a boundary, the degradation, preservation, fluctuation and enhancement of QFI are dependent on the evolution time, boundary and acceleration. In addition, the existing boundary can effectively shield QFI from the influence of the vacuum fluctuation and Unruh thermal effect. Especially, the QFI seems to be unaffected by the vacuum fluctuation and acceleration when the atom is very close to the boundary. The efficient control of the boundary and acceleration can provide the feasible scheme of improving the parameter estimation precision.

Dynamics of quantum correlation for circularly accelerated atoms immersed in a massless scalar field near a boundary

2019 ◽  
Vol 34 (36) ◽  
pp. 1950297
Author(s):  
Zhiming Huang ◽  
Yiyong Ye ◽  
Xiaobin Wang ◽  
Xiaokui Sheng ◽  
Xiaoyun Xia ◽  
...  
Keyword(s):  
Scalar Field ◽  
Master Equation ◽  
Quantum Correlation ◽  
Plane Boundary ◽  
Thermal Bath ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
System Evolution

In this paper, we explore the dynamics of quantum correlation for two circularly accelerated atoms interacting with a bath of fluctuating massless scalar field with a reflecting plane boundary. First, we derive the master equation that governs the system evolution. Then we analyze the behaviors of quantum correlation for various conditions and compare the behaviors of quantum correlation with that of the static atoms immersed in a thermal bath with a boundary. It is found that the dynamics of quantum correlation for circularly accelerated atoms present some features distinct from those of static atoms immersed in a thermal bath.

scholarly journals A ROTATING QUANTUM VACUUM AND THE DEPOLARIZATION PROBLEM IN STORAGE RINGS

1999 ◽  
Vol 14 (05) ◽  
pp. 717-729 ◽  
Author(s):  
V. A. DE LORENCI ◽  
N. F. SVAITER
Keyword(s):  
Scalar Field ◽  
Rest Frame ◽  
Inertial Frame ◽  
Point Of View ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Rotating Frame ◽  
Quantum Vacuum ◽  
Polarization Effects ◽  
Radiative Processes

We investigate how a uniformly rotating frame is defined as the rest frame of an observer rotating with constant angular velocity Ω around the z axis of an inertial frame. Assuming that this frame is a Lorentz one, we second quantize a free massless scalar field in this rotating frame and obtain a new rotating vacuum (of a massless scalar field) different from the Minkowski one. After this we consider a monopole detector interacting with the field. The radiative processes are discussed from a rotating and inertial frame point of view. Finally using this formalism, the polarization effects of electrons in circular accelerators is discussed.

scholarly journals Violation of Bell-CHSH Inequalities through Optimal Local Filters in the Vacuum

2020 ◽  
Vol 2 (4) ◽  
pp. 542-559
Author(s):  
Akira Matsumura ◽  
Yasusada Nambu
Keyword(s):  
Scalar Field ◽  
Success Probability ◽  
Vacuum State ◽  
Quantum Correlations ◽  
Entangled State ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Chsh Inequality ◽  
Local Filters ◽  
Chsh Inequalities

We investigate quantum correlations appearing for two-qubit detectors which are initially uncorrelated and locally coupled to a massless scalar field in a vacuum state. Under the perturbation up to the second order in the coupling, the state of the detectors can be entangled through the interaction with the scalar field but satisfies the Bell-CHSH inequality. The violation of the Bell-CHSH inequality for such an entangled state is revealed by local filtering operations. In this paper, we construct the optimal filtering operations for the qubit detectors and derive the success probability of the filtering. The success probability characterizes the reliability of revealing the violation of the Bell-CHSH inequality by the filtering operations. Through these analyses, we demonstrate a trade-off relation between the success probability and the size of parameter region showing the violation of the Bell-CHSH inequality.

scholarly journals Vacuum Polarization in a Zero-Width Potential: Self-Adjoint Extension

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 127
Author(s):  
Yuri V. Grats ◽  
Pavel Spirin
Keyword(s):  
Scalar Field ◽  
Vacuum Polarization ◽  
Dimensional Regularization ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Field Approximation ◽  
Dimensional Euclidean Space ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Adjoint Extension

The effects of vacuum polarization associated with a massless scalar field near pointlike source with a zero-range potential in three spatial dimensions are analyzed. The “physical” approach consists in the usage of direct delta-potential as a model of pointlike interaction. We use the Perturbation theory in the Fourier space with dimensional regularization of the momentum integrals. In the weak-field approximation, we compute the effects of interest. The “mathematical” approach implies the self-adjoint extension technique. In the Quantum-Field-Theory framework we consider the massless scalar field in a 3-dimensional Euclidean space with an extracted point. With appropriate boundary conditions it is considered an adequate mathematical model for the description of a pointlike source. We compute the renormalized vacuum expectation value ⟨ϕ2(x)⟩ren of the field square and the renormalized vacuum averaged of the scalar-field’s energy-momentum tensor ⟨Tμν(x)⟩ren. For the physical interpretation of the extension parameter we compare these results with those of perturbative computations. In addition, we present some general formulae for vacuum polarization effects at large distances in the presence of an abstract weak potential with finite-sized compact support.

scholarly journals Open quantum entanglement: a study of two atomic system in static patch of de Sitter space

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Samim Akhtar ◽  
Sayantan Choudhury ◽  
Satyaki Chowdhury ◽  
Debopam Goswami ◽  
Sudhakar Panda ◽  
...  
Keyword(s):  
Scalar Field ◽  
Density Matrix ◽  
Master Equation ◽  
Quantum Entanglement ◽  
De Sitter Space ◽  
Thermal Bath ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Open Quantum ◽  
Non Locality

Abstract In this work, our prime objective is to study non-locality and long range effect of two body correlation using quantum entanglement from various information theoretic measure in the static patch of de Sitter space using a two body Open Quantum System (OQS). The OQS is described by a system of two entangled atoms, surrounded by a thermal bath, which is modelled by a massless probe scalar field. Firstly, we partially trace over the bath field and construct the Gorini Kossakowski Sudarshan Lindblad (GSKL) master equation, which describes the time evolution of the reduced subsystem density matrix. This GSKL master equation is characterized by two components, these are-Spin chain interaction Hamiltonian and the Lindbladian. To fix the form of both of them, we compute the Wightman functions for probe massless scalar field. Using this result alongwith the large time equilibrium behaviour we obtain the analytical solution for reduced density matrix. Further using this solution we evaluate various entanglement measures, namely Von-Neumann entropy, R$$e'$$e′nyi entropy, logarithmic negativity, entanglement of formation, concurrence and quantum discord for the two atomic subsystem on the static patch of De-Sitter space. Finally, we have studied violation of Bell-CHSH inequality, which is the key ingredient to study non-locality in primordial cosmology.

VACUUM ENERGY IN SPHERICAL DOMAINS: WKB AND UNIFORM ASYMPTOTIC EXPANSIONS

1996 ◽  
Vol 11 (22) ◽  
pp. 4129-4146 ◽  
Author(s):  
AUGUST ROMEO
Keyword(s):  
Zeta Function ◽  
Asymptotic Expansions ◽  
Zero Point ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Point Energy ◽  
Dimensional Dependence ◽  
Spherical Domains ◽  
Spectral Zeta Function ◽  
Uniform Asymptotic Expansions

We evaluate the finite part of the regularized zero-point energy for a massless scalar field confined in the interior of a D-dimensional spherical region. While some insight is offered into the dimensional dependence of the WKB approximations by examining the residues of the spectral-zeta-function poles, a mode-sum technique based on an integral representation of the Bessel spectral zeta function is applied with the help of uniform asymptotic expansions (u.a.e.’s).

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