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:quant-ph/0309175 · Physical Review A

Nonclassical photon pairs generated from a room-temperature atomic ensemble

Wei Jiang, Chao Han, Peng Xue, L.-M. Duan, Guang‐Can Guo

Published Apr 28, 2004• 43 citations
arXivHTMLPDF

Abstract

We report experimental generation of nonclassically correlated photon pairs from collective emission in a room-temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons is separated by a controllable time delay up to $2\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{s}$. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.

DOI
10.1103/physreva.69.043819

Related papers

Nonclassical photon pairs generated by a room-temperature atomic ensemble

Wei Jiang, Chao Han, Peng Xue +2 more

We report experimental generation of nonclassically correlated photon pairs from collective emission in a room temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons are separated by a controllable time delay up to 2 microseconds. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 25, 2004•1 citation

Nonclassical photon pair generation in atomic vapors

S. N. Sandhya

A scheme for the generation of nonclassical pairs of photons in atomic vapors is proposed. The scheme exploits the fact that the cross correlation of the emission of photons from the extreme transitions of a four-level cascade system shows antibunching, unlike the case of the three-level cascade emission, which shows bunching. The Cauchy-Schwarz inequality, which is the ratio of the cross-correlation to the autocorrelation function, in this case is estimated to be ${10}^{3}--{10}^{6}$ for controllable time delay, and is one to four orders of magnitude larger compared to previous experiments. The choice of Doppler-free geometry, in addition to the fact that at three-photon resonance the excitation and deexcitation processes occur in a very narrow frequency band, ensures cleaner signals.

arXiv:0707.0720•Physical Review A•Jul 3, 2007•1 citation

Temporal Dynamics of Photon Pairs Generated by an Atomic Ensemble

Sergey Vladimirovich Polyakov, C. W. Chou, D. Felinto +1 more

The time dependence of nonclassical correlations is investigated for two fields $(1,2)$ generated by an ensemble of cold cesium atoms via the protocol of Duan et al. [Nature (London) 414, 413 (2001)]. The correlation function $R({t}_{1},{t}_{2})$ for the ratio of cross to autocorrelations for the $(1,2)$ fields at times $({t}_{1},{t}_{2})$ is found to have a maximum value ${R}^{\mathrm{max}}=292\ifmmode\pm\else\textpm\fi{}57$, which significantly violates the Cauchy-Schwarz inequality $R\ensuremath{\le}1$ for classical fields. Decoherence of quantum correlations is observed over ${\ensuremath{\tau}}_{d}\ensuremath{\simeq}175\text{ }\text{ }\mathrm{n}\mathrm{s}$, and is described by our model, as is a new scheme to mitigate this effect.

arXiv:quant-ph/0406050•Physical Review Letters•Dec 20, 2004•44 citations

Quantum theory for generation of nonclassical photon pairs by a medium with collective atomic memory

Narek Sisakyan, Yuri P. Malakyan

We present the quantum theory for creation of collective atomic memory and generation of nonclassically correlated photon pairs from an ensemble via the protocol of Duan et al. [Nature (London) 414, 413 (2001)]. The temporal evolution of photon numbers, photon statistics, and cross-correlation between the Stokes and anti-Stokes fields is found by solving the equation of motion for atomic spin-wave excitations. We consider a low-finesse cavity model with collectively enhanced signal-to-noise ratio, which remains still considerably large in the free-space limit. Our results describe analytically the dependence of quantum correlations on spin decoherence time and time delay between the write and read lasers and reproduce the observed data very well including the generated pulse shapes, strong violation of Cauchy-Schwarz inequality and conditional generation of anti-Stokes single-photon pulse. The approach we developed may be used also for quantum description of storage and retrieval of quantum information, especially when the statistical properties of nonclassical pulses are studied.

arXiv:quant-ph/0503186•Physical Review A•Oct 12, 2005•5 citations

Non-degenerated nonclassical photon pairs in a hot atomic ensemble

Qunfeng Chen, Bao‐Sen Shi, Min Hua Feng +2 more

We experimentally demonstrate the generation of non-degenerate nonclassical paired photons in a hot atomic ensemble using off-axis four-wave mixing. The time-resolved second-order correlated function between the Stokes photon and the anti-Stokes photon is given. The two-photon correlation between the photons obtained in this experiment is 1.87+/- 0.04, which leads to the violation of Cauchy-Schwarz inequality by a factor of 1.69+/- 0.14.

Optics Express•Dec 16, 2008•35 citations

A broadband DLCZ quantum memory in room-temperature atoms

Jian-Peng Dou, Ai-Lin Yang, Mu-Yan Du +8 more

Abstract Quantum memory capable of stopping flying photons and storing their quantum coherence is essential for scalable quantum technologies. A room-temperature broadband quantum memory will enable the implementation of large-scale quantum systems for real-life applications. Due to either intrinsic high noises or short lifetime, it is still challenging to find a room-temperature broadband quantum memory beyond conceptual demonstration. Here, we present a far off-resonance Duan–Lukin–Cirac–Zoller (FORD) protocol and demonstrate the broadband quantum memory in room-temperature atoms. We observe a low unconditional noise level of 10−4 and a cross-correlation up to 28. A strong violation of Cauchy–Schwarz inequality indicates high-fidelity generation and preservation of non-classical correlation. Furthermore, the achieved cross-correlation in room-temperature atoms exceeds the key boundary of 6, above which quantum correlation is able to violate Bell’s inequality. Our results open up the door to an entirely new realm of memory-enabled quantum applications at ambient conditions.

arXiv:1704.06309•Communications Physics•Sep 14, 2018•46 citations
We report experimental generation of nonclassically correlated photon pairs from collective emission in a room-temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons is separated by a controllable time delay up to 2\ensuremathμs2\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{s}2\ensuremathμs. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.
We report experimental generation of nonclassically correlated photon pairs from collective emission in a room temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons are separated by a controllable time delay up to 2 microseconds. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.
A scheme for the generation of nonclassical pairs of photons in atomic vapors is proposed. The scheme exploits the fact that the cross correlation of the emission of photons from the extreme transitions of a four-level cascade system shows antibunching, unlike the case of the three-level cascade emission, which shows bunching. The Cauchy-Schwarz inequality, which is the ratio of the cross-correlation to the autocorrelation function, in this case is estimated to be 103−−106{10}^{3}--{10}^{6}103−−106 for controllable time delay, and is one to four orders of magnitude larger compared to previous experiments. The choice of Doppler-free geometry, in addition to the fact that at three-photon resonance the excitation and deexcitation processes occur in a very narrow frequency band, ensures cleaner signals.
The time dependence of nonclassical correlations is investigated for two fields (1,2)(1,2)(1,2) generated by an ensemble of cold cesium atoms via the protocol of Duan et al. [Nature (London) 414, 413 (2001)]. The correlation function R(t1,t2)R({t}_{1},{t}_{2})R(t1​,t2​) for the ratio of cross to autocorrelations for the (1,2)(1,2)(1,2) fields at times (t1,t2)({t}_{1},{t}_{2})(t1​,t2​) is found to have a maximum value ${R}^{\mathrm{max}}=292\ifmmode\pm\else\textpm\fi{}57$, which significantly violates the Cauchy-Schwarz inequality $R\ensuremath{\le}1$ for classical fields. Decoherence of quantum correlations is observed over ${\ensuremath{\tau}}_{d}\ensuremath{\simeq}175\text{ }\text{ }\mathrm{n}\mathrm{s}$, and is described by our model, as is a new scheme to mitigate this effect.
We present the quantum theory for creation of collective atomic memory and generation of nonclassically correlated photon pairs from an ensemble via the protocol of Duan et al. [Nature (London) 414, 413 (2001)]. The temporal evolution of photon numbers, photon statistics, and cross-correlation between the Stokes and anti-Stokes fields is found by solving the equation of motion for atomic spin-wave excitations. We consider a low-finesse cavity model with collectively enhanced signal-to-noise ratio, which remains still considerably large in the free-space limit. Our results describe analytically the dependence of quantum correlations on spin decoherence time and time delay between the write and read lasers and reproduce the observed data very well including the generated pulse shapes, strong violation of Cauchy-Schwarz inequality and conditional generation of anti-Stokes single-photon pulse. The approach we developed may be used also for quantum description of storage and retrieval of quantum information, especially when the statistical properties of nonclassical pulses are studied.
Abstract Quantum memory capable of stopping flying photons and storing their quantum coherence is essential for scalable quantum technologies. A room-temperature broadband quantum memory will enable the implementation of large-scale quantum systems for real-life applications. Due to either intrinsic high noises or short lifetime, it is still challenging to find a room-temperature broadband quantum memory beyond conceptual demonstration. Here, we present a far off-resonance Duan–Lukin–Cirac–Zoller (FORD) protocol and demonstrate the broadband quantum memory in room-temperature atoms. We observe a low unconditional noise level of 10−4 and a cross-correlation up to 28. A strong violation of Cauchy–Schwarz inequality indicates high-fidelity generation and preservation of non-classical correlation. Furthermore, the achieved cross-correlation in room-temperature atoms exceeds the key boundary of 6, above which quantum correlation is able to violate Bell’s inequality. Our results open up the door to an entirely new realm of memory-enabled quantum applications at ambient conditions.