Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1201.0522 · International Journal of Modern Physics E

ENTANGLEMENT GENERATION BY TIME VARYING REFRACTIVE INDEX: ANALOGY WITH COSMOLOGICAL MODEL

Shahpoor Moradi

Published Jan 1, 2011• 0 citations
arXivHTMLPDF

Abstract

Generation of entanglement between modes of electromagnetic fields by sudden change of the refractive index of a medium is considered. We use the analogy between the Fock-space formulation of pair creation caused by the contraction and expansion of the universe on one hand and the pair creation in time-dependent electric fields on the other hand. It is shown that entanglement between photons encodes information concerning the underlying refractive index of a medium.

DOI
10.1142/s0218301311017405

Related papers

Time reflection of light from a quantum perspective and vacuum entanglement

Anatoly A. Svidzinsky

If a boundary between two static media is moving with a constant superluminal velocity, or there is a sudden change of the refractive index with time, this yields generation of entangled pairs of photons out of vacuum propagating in the opposite directions. Here we show that during this process, entanglement of Minkowski vacuum is transferred to the entanglement of the generated photon pairs. If initially an electromagnetic pulse is present in the medium the photon generation is stimulated into the pulse mode, and since photons are created as entangled pairs the counter-propagating photon partners produce a pulse moving in the opposite direction, which is known as time reflection. Thus, time reflection occurs due to stimulated generation of the entangled photon pairs out of entangled vacuum and no photons in the original pulse are in fact being reflected. This is different from the mechanism of light reflection from spatial inhomogeneities for which no photons are generated.

Optics Express•Apr 4, 2024•8 citations

A CASE OF ENTANGLEMENT GENERATION BETWEEN CAUSALLY DISCONNECTED ATOMS

Juan León, Carlos Sabín

We analyze the entanglement generated in a finite time between a pair of space-like separated atoms, one of which emits a photon. As we show to order e2, the origin of entanglement can be traced back to the uncertainty about which one of the atoms emitted the photon. We check this by comparing the time behaviors of the emission processes allowed by energy conservation versus those forbidden by the same reason. No physical signal propagates between the atoms in the processes considered, however an effective light cone separating non-entangled from entangled regions in space-time emerges from our calculations.

arXiv:0805.2110•International Journal of Quantum Information•Jan 1, 2009•4 citations

EFFECTS OF APPLIED ELECTRIC FIELDS ON LINEAR AND NONLINEAR INTERSUBBAND REFRACTIVE INDEX CHANGES IN SEMI-PARABOLIC QUANTUM WELLS

Zhang Li

By using the compact density matrix approach and displacement harmonic variant and numerical calculation methods,the linear and nonlinear intersubband refractive index changes(RICs) in a semi-parabolic quantum well with applied electric field were investigated in detail.Numerical calculations on GaAs were performed for the dependence of RIC on the incident optical intensity,the frequency of confined potential of the semi-parabolic quantum well and the strength of applied electric field.Results reveal that the RICs in the semi-parabolic quantum well system sensitively depend on these factors.

JOURNAL OF INFRARED AND MILLIMETER WAVES•Jan 1, 2005•0 citations

GAIN-ASSISTED NEGATIVE REFRACTIVE INDEX IN A QUANTUM COHERENT MEDIUM

Jian-Qi Shen

A new scheme for overcoming losses with incoherent optical gain in a quantum-coherent left-handed atomic vapor is suggested. In order to obtain low-loss, lossless or active left-handed media (LHM), a pump fleld, which aims at realizing population inversion of atomic levels, is introduced into a four-level atomic system. Both analytical and numerical results are given to illustrate that such an atomic vapor can exhibit intriguing electric and magnetic responses required for achieving simultaneously negative permittivity and permeability (and hence a gain-assisted quantum-coherent negative refractive index would emerge). The quantum-coherent left-handed atomic vapor presented here could have four fascinating characteristics: i) three-dimensionally isotropic negative refractive index, ii) double- negative atomic medium at visible and infrared wavelengths, iii) high-gain optical ampliflcation, and iv) tunable negative refractive index based on quantum coherent control. Such a three-dimensionally isotropic gain medium with negative refractive index at visible and infrared frequencies would have a potential application in design of new quantum optical and photonic devices, including superlenses for perfect imaging and subwavelength focusing.

Electromagnetic waves•Jan 1, 2013•11 citations

Entanglement from longitudinal and scalar photons

J. D. Franson

A covariant treatment of the electromagnetic field requires the introduction of longitudinal and scalar photons in addition to the usual transverse photons. It is shown that these additional photons can produce entanglement between distant atoms.

International Conference on Quantum Information•Jan 1, 2011•0 citations

Temporal and diffraction effects in entanglement creation in an optical cavity

Sonny Natali, Z. Ficek

A practical scheme for entanglement creation between distant atoms located inside a single-mode optical cavity is discussed. We show that the degree of entanglement and the time it takes for the entanglement to reach its optimum value is a sensitive function of the initial conditions and the position of the atoms inside the cavity mode. It is found that the entangled properties of the two atoms can readily be extracted from dynamics of a simple two-level system. Effectively, we engineer two coupled qubits whose dynamics are analogous to that of a driven single two-level system. It is found that spatial variations of the coupling constants actually help to create transient entanglement which may appear on the time scale much longer than that predicted for the case of equal coupling constants. When the atoms are initially prepared in an entangled state, they may remain entangled for all times. We also find that the entanglement exhibits an interesting phenomenon of diffraction when the atoms are located between the nodes and antinodes of the cavity mode. The diffraction pattern of the entanglement varies with time and we explain this effect in terms of the quantum property of complementarity, which is manifested as a tradeoff between the knowledge of energy of the exchanged photon versus the evolution time of the system.

arXiv:0704.2269•Physical Review A•Apr 9, 2007•49 citations
Generation of entanglement between modes of electromagnetic fields by sudden change of the refractive index of a medium is considered. We use the analogy between the Fock-space formulation of pair creation caused by the contraction and expansion of the universe on one hand and the pair creation in time-dependent electric fields on the other hand. It is shown that entanglement between photons encodes information concerning the underlying refractive index of a medium.
If a boundary between two static media is moving with a constant superluminal velocity, or there is a sudden change of the refractive index with time, this yields generation of entangled pairs of photons out of vacuum propagating in the opposite directions. Here we show that during this process, entanglement of Minkowski vacuum is transferred to the entanglement of the generated photon pairs. If initially an electromagnetic pulse is present in the medium the photon generation is stimulated into the pulse mode, and since photons are created as entangled pairs the counter-propagating photon partners produce a pulse moving in the opposite direction, which is known as time reflection. Thus, time reflection occurs due to stimulated generation of the entangled photon pairs out of entangled vacuum and no photons in the original pulse are in fact being reflected. This is different from the mechanism of light reflection from spatial inhomogeneities for which no photons are generated.
We analyze the entanglement generated in a finite time between a pair of space-like separated atoms, one of which emits a photon. As we show to order e2, the origin of entanglement can be traced back to the uncertainty about which one of the atoms emitted the photon. We check this by comparing the time behaviors of the emission processes allowed by energy conservation versus those forbidden by the same reason. No physical signal propagates between the atoms in the processes considered, however an effective light cone separating non-entangled from entangled regions in space-time emerges from our calculations.
By using the compact density matrix approach and displacement harmonic variant and numerical calculation methods,the linear and nonlinear intersubband refractive index changes(RICs) in a semi-parabolic quantum well with applied electric field were investigated in detail.Numerical calculations on GaAs were performed for the dependence of RIC on the incident optical intensity,the frequency of confined potential of the semi-parabolic quantum well and the strength of applied electric field.Results reveal that the RICs in the semi-parabolic quantum well system sensitively depend on these factors.
A new scheme for overcoming losses with incoherent optical gain in a quantum-coherent left-handed atomic vapor is suggested. In order to obtain low-loss, lossless or active left-handed media (LHM), a pump fleld, which aims at realizing population inversion of atomic levels, is introduced into a four-level atomic system. Both analytical and numerical results are given to illustrate that such an atomic vapor can exhibit intriguing electric and magnetic responses required for achieving simultaneously negative permittivity and permeability (and hence a gain-assisted quantum-coherent negative refractive index would emerge). The quantum-coherent left-handed atomic vapor presented here could have four fascinating characteristics: i) three-dimensionally isotropic negative refractive index, ii) double- negative atomic medium at visible and infrared wavelengths, iii) high-gain optical ampliflcation, and iv) tunable negative refractive index based on quantum coherent control. Such a three-dimensionally isotropic gain medium with negative refractive index at visible and infrared frequencies would have a potential application in design of new quantum optical and photonic devices, including superlenses for perfect imaging and subwavelength focusing.
A practical scheme for entanglement creation between distant atoms located inside a single-mode optical cavity is discussed. We show that the degree of entanglement and the time it takes for the entanglement to reach its optimum value is a sensitive function of the initial conditions and the position of the atoms inside the cavity mode. It is found that the entangled properties of the two atoms can readily be extracted from dynamics of a simple two-level system. Effectively, we engineer two coupled qubits whose dynamics are analogous to that of a driven single two-level system. It is found that spatial variations of the coupling constants actually help to create transient entanglement which may appear on the time scale much longer than that predicted for the case of equal coupling constants. When the atoms are initially prepared in an entangled state, they may remain entangled for all times. We also find that the entanglement exhibits an interesting phenomenon of diffraction when the atoms are located between the nodes and antinodes of the cavity mode. The diffraction pattern of the entanglement varies with time and we explain this effect in terms of the quantum property of complementarity, which is manifested as a tradeoff between the knowledge of energy of the exchanged photon versus the evolution time of the system.