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

Chinese Physics Letters

Enhancement of Continuous Variable Entanglement in Four-Wave Mixing due to Atomic Memory Effects

Zhu Yu-Zhu, Xiangming Hu, Wang Fei, Li Jing-Yan

Published Apr 1, 2010• 5 citations
Publisher

Abstract

We explore the effects of atomic memory on quantum correlations of two-mode light fields from four-wave mixing. A three-level atomic system in Λ configuration is considered, in which the atomic relaxation times are comparable to or longer than the cavity relaxation times and thus there exists the atomic memory. The quantum correlation spectrum in the output is calculated without the adiabatic elimination of atomic variables. It is shown that the continuous variable entanglement is enhanced over a wide range of the normalized detuning in the intermediate and bad cavity cases compared with the good cavity case. In some situations more significant enhancement occurs at sidebands.

DOI
10.1088/0256-307x/27/4/044210

Related papers

Einstein-Podolsky-Rosen entanglement in bad cavity case

Yuan Sui-Hong, Xiangming Hu

This paper explores continuous variable entanglement in four-wave mixing when the atomic relaxation time is comparable to and longer than the cavity relaxation time. In this case the atomic memory is included in the field correlations and the entanglement in the output fields can be significantly enhanced. Einstein–Podolsky–Rosen (EPR) entanglement is achievable even in the bad cavity limit. This shows the EPR entanglement generation without need of good cavity.

Chinese Physics B•Jul 1, 2010•2 citations

Enhancement of quantum correlations between Rabi sidebands via dressed population transfer

Jingyan Li, Xiangming Hu

We analyse the effects of coherent or incoherent dressed population transfer on two-mode squeezing and continuous variable entanglement in four-wave mixing. Two cavity modes are generated from Rabi sidebands of dressed two-level atoms. A weak coherent or incoherent field couples one dressed state to an auxiliary excited state, from which the atoms decay to the other dressed state. This provides a two-step channel for dressed population transfer and reduces spontaneous emission into a squeeze-transformed mode that enters into an interaction with the dressed atoms. It is the reduction of spontaneous emission that leads to an enhancement of two-mode squeezing, whose degree is increased to 75% compared with 50% for the two-level case. This corresponds to a significant enhancement of the continuous variable entanglement.

Journal of Physics B Atomic Molecular and Optical Physics•Feb 16, 2009•11 citations

Cavity-assisted squeezing and entanglement: non-adiabatic effects and optimal cavity-atomic ensemble matching

Natalia Masalaeva, Anton N. Vetlugin, I. V. Sokolov

Abstract We investigate theoretically quantum entanglement of light with the collective spin polarization of a cold atomic ensemble in cavity-assisted Raman schemes. Previous works concentrated mostly on the bad cavity limit where the signals are much longer than the cavity field lifetime. In view of atomic relaxation and other imperfections, there may arise a need to speed-up the light-atoms interface operation. By increasing the cavity field lifetime, one can achieve better light–matter coupling and entanglement. In our work, we consider the non-adiabatic effects that become important beyond the bad cavity limit in both low-photon and continuous variables regime. We find classical control field time profiles that allow one to retrieve from the cavity an output quantized signal of a predefined time shape and duration, which is optimal for the homodyne detection, optical mixing or further manipulation. This is done for a wide range of the signal duration as compared to the cavity field lifetime. We discuss an optimal cavity–atomic ensemble matching in terms of the cavity field lifetime which allows one to apply less intense control field and to minimize a variety of nonlinear effects, such as AC light shifts, four-wave mixing, etc, which may be potentially harmful to an experiment.

arXiv:1908.07022•Physica Scripta•Oct 30, 2019•3 citations

High-Frequency Einstein–Podolsky–Rosen Entanglement via Atomic Memory Effects in Four-Wave Mixing

Xuehua Zhang, Xiangming Hu, Kong Ling-Feng +1 more

Atomic memory effects occur when the atomic relaxation times are comparable to or much longer than the cavity relaxation times. We show that by using the memory effects, it is possible to obtain high-frequency Einstein–Podolsky–Rosen entanglement between a pair of Stokes and anti-Stokes fields in a four-wave mixing system. The physical origin is traced to the dynamical Stark splittings of dressed states due to the parametrically amplified fields. This mechanism provides an alternative and efficient way for sideband entanglement.

Chinese Physics Letters•Sep 1, 2010•1 citation

ETUDE THEORIQUE ET EXPERIMENTALE DES CORRELATIONS QUANTIQUES OBTENUES PAR MELANGE A QUATRE ONDES DANS UNE VAPEUR ATOMIQUE

Quentin C. Glorieux

Abstract We study both theoretically and experimentally the generation of quantum correlations in the continuous variable regime by way of four-wave mixing in a hot atomic vapor. Two theoretical approaches have been developed. On one side, we study the four- wave mixing under the "classical" non-linear optics point of view. In such a way we obtain the evolution equation for an ideal linear amplifier in a χ(3) medium. On the other side, we present a microscopic model with 4 levels in the double-Λ configuration to calculate the χ(3) coefficient in a atomic vapor dressed with a laser. This calculation allows us to derive the spectra of intensity noise for interesting parameters. The experimental part of this work describes the demonstration of this effect on the D1 line of rubidium 85. We present a measurement of relative intensity squeezing as high as -9.2dB below the standard quantum limit, and an original regime where quantum correlations have been measured without amplification. These results have broad applications in the field of multimode quantum optics, e.g. quantum imaging or the multimode quantum memories. Keywords quantum fluctuations, squeezing, quantum correlations, atomic vapor, four wave mixing, continuous variable, entanglement.

•Nov 19, 2010•6 citations

Entanglement of three-mode light via six-wave mixing in a four-level Y-type atomic system

Wenxing Shi, Xiangming Hu, Jingyan Li +1 more

In this paper, we show that it is possible to achieve continuous-variable entanglement of three optical fields in a four-level Y-type atomic system. The three fields are amplified through the Rabi resonances of the different driven transitions. Two fields from the V configuration are in one quantum beat and in the mixing parametric interactions with the third field from the lower transition. This yields entanglement between the pair of beat modes and the third field. The best achievable state in the output approaches the Einstein–Podolsky–Rosen entangled state.

Journal of Physics B Atomic Molecular and Optical Physics•Jul 20, 2010•11 citations
We explore the effects of atomic memory on quantum correlations of two-mode light fields from four-wave mixing. A three-level atomic system in Λ configuration is considered, in which the atomic relaxation times are comparable to or longer than the cavity relaxation times and thus there exists the atomic memory. The quantum correlation spectrum in the output is calculated without the adiabatic elimination of atomic variables. It is shown that the continuous variable entanglement is enhanced over a wide range of the normalized detuning in the intermediate and bad cavity cases compared with the good cavity case. In some situations more significant enhancement occurs at sidebands.
We analyse the effects of coherent or incoherent dressed population transfer on two-mode squeezing and continuous variable entanglement in four-wave mixing. Two cavity modes are generated from Rabi sidebands of dressed two-level atoms. A weak coherent or incoherent field couples one dressed state to an auxiliary excited state, from which the atoms decay to the other dressed state. This provides a two-step channel for dressed population transfer and reduces spontaneous emission into a squeeze-transformed mode that enters into an interaction with the dressed atoms. It is the reduction of spontaneous emission that leads to an enhancement of two-mode squeezing, whose degree is increased to 75% compared with 50% for the two-level case. This corresponds to a significant enhancement of the continuous variable entanglement.
Abstract We investigate theoretically quantum entanglement of light with the collective spin polarization of a cold atomic ensemble in cavity-assisted Raman schemes. Previous works concentrated mostly on the bad cavity limit where the signals are much longer than the cavity field lifetime. In view of atomic relaxation and other imperfections, there may arise a need to speed-up the light-atoms interface operation. By increasing the cavity field lifetime, one can achieve better light–matter coupling and entanglement. In our work, we consider the non-adiabatic effects that become important beyond the bad cavity limit in both low-photon and continuous variables regime. We find classical control field time profiles that allow one to retrieve from the cavity an output quantized signal of a predefined time shape and duration, which is optimal for the homodyne detection, optical mixing or further manipulation. This is done for a wide range of the signal duration as compared to the cavity field lifetime. We discuss an optimal cavity–atomic ensemble matching in terms of the cavity field lifetime which allows one to apply less intense control field and to minimize a variety of nonlinear effects, such as AC light shifts, four-wave mixing, etc, which may be potentially harmful to an experiment.
Atomic memory effects occur when the atomic relaxation times are comparable to or much longer than the cavity relaxation times. We show that by using the memory effects, it is possible to obtain high-frequency Einstein–Podolsky–Rosen entanglement between a pair of Stokes and anti-Stokes fields in a four-wave mixing system. The physical origin is traced to the dynamical Stark splittings of dressed states due to the parametrically amplified fields. This mechanism provides an alternative and efficient way for sideband entanglement.
Abstract We study both theoretically and experimentally the generation of quantum correlations in the continuous variable regime by way of four-wave mixing in a hot atomic vapor. Two theoretical approaches have been developed. On one side, we study the four- wave mixing under the "classical" non-linear optics point of view. In such a way we obtain the evolution equation for an ideal linear amplifier in a χ(3) medium. On the other side, we present a microscopic model with 4 levels in the double-Λ configuration to calculate the χ(3) coefficient in a atomic vapor dressed with a laser. This calculation allows us to derive the spectra of intensity noise for interesting parameters. The experimental part of this work describes the demonstration of this effect on the D1 line of rubidium 85. We present a measurement of relative intensity squeezing as high as -9.2dB below the standard quantum limit, and an original regime where quantum correlations have been measured without amplification. These results have broad applications in the field of multimode quantum optics, e.g. quantum imaging or the multimode quantum memories. Keywords quantum fluctuations, squeezing, quantum correlations, atomic vapor, four wave mixing, continuous variable, entanglement.
In this paper, we show that it is possible to achieve continuous-variable entanglement of three optical fields in a four-level Y-type atomic system. The three fields are amplified through the Rabi resonances of the different driven transitions. Two fields from the V configuration are in one quantum beat and in the mixing parametric interactions with the third field from the lower transition. This yields entanglement between the pair of beat modes and the third field. The best achievable state in the output approaches the Einstein–Podolsky–Rosen entangled state.