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

Optics Express

Efficient generation of heralded narrowband color-entangled states

Xiaojun Zhang, Jin‐Hui Wu, Giuseppe Carlo La Rocca, M. Artoni

Published Sep 1, 2020• 3 citations
Publisher

Abstract

We show that narrowband two-color entangled single Stokes photons can be generated in a ultra-cold atoms sample via selective excitation of two spontaneous four-wave mixing (SFWM) processes. Under certain circumstances, the generation, heralded by the respective common anti-Stokes photon, is robust against losses and phase-mismatching and is remarkably efficient owing to balanced resonant enhancement of the two four-wave mixing processes in a regime of combined induced transparency. Maximally color-entangled states can be easily attained by adjusting the detunings of the external couplings and driving fields, even when these are quite weak.

DOI
10.1364/oe.401551

Related papers

Engineering of heralded narrowband color-entangled states

Alessandro Zavatta, M. Artoni, G. La Rocca

The efficient generation of entanglement is an essential requirement for quantum communications; however, long distances can only be achieved by utilizing entangled states that can be efficiently mapped into matter. Hence, sources generating states with bandwidths naturally compatible with the linewidths of atomic transitions are crucial. We harness the indistinguishability between two spontaneous four-wave mixing processes to achieve the heralded generation of single-photon frequency-bin entangled states. State manipulation admits entanglement and generation probability optimizations yet with negligible absorption. The scheme could also be adapted to photonic and solid interfaces.

arXiv:1809.03456•Physical Review A•Mar 19, 2019•10 citations

Nonlocal Rydberg enhancement for four-wave-mixing biphoton generation

Hui-Min Zhao, Xiaojun Zhang, M. Artoni +2 more

Tunable Rydberg interactions in cold atoms can be used to generate strongly correlated photon pairs through a spontaneous four-wave-mixing process in which all driving fields are allowed to work on resonance. The scheme relies on electromagnetically induced transparency and an imbalanced dark state with most atoms trapped in a ground state and a weakly populated Rydberg state. We show in particular that the combination of these two effects results in negligible linear absorption and Raman gain at the Stokes and anti-Stokes frequencies of generated photon pairs, while the nonlocal (Rydberg) nonlinearities contribute significantly to the enhancement of photon-pair generation rates and cross correlations at very low pump strengths and optical depths.

Physical Review A•Apr 16, 2024•8 citations

Counter-propagating spontaneous four wave mixing: photon-pair factorability and ultra-narrowband single photons

Jorge Monroy-Ruz, Karina Garay-Palmett, Alfred B U’Ren

We introduce a new kind of spontaneous four wave mixing process for the generation of photon pairs, in which the four waves involved counter-propagate in a guided-wave medium; we refer to this process as counter-propagating spontaneous four wave mixing (CP-SFWM). We show that for the simplest CP-SFWM source, in which all waves propagate in the same polarization and transverse mode and in which self- and cross-phase modulation effects are negligible, phasematching is attained automatically regardless of dispersion in the fiber or waveguide. Furthermore, we show that in two distinct versions of this source (both pumps pulsed, or one pump pulsed and the remaining one monochromatic), the two-photon state is automatically factorable provided that the length of the nonlinear medium exceeds a certain threshold, easily achievable in practice since this threshold length tends to be in the range of mm to cm. We also show that if one of the pumps approaches the monochromatic limit, and for a sufficient nonlinear medium length, the bandwidth of one of the two photons in a given pair may be reduced to the level of MHz, compatible with electronic transitions for the implementation of atom–photon interfaces, without the use of optical cavities.

arXiv:1609.04663•New Journal of Physics•Oct 19, 2016•10 citations

Photon pairs with coherence time exceeding 1 μs

Luwei Zhao, Xianxin Guo, Chang Liu +3 more

The generation of nonclassical photon pairs with a long coherence time is key for applications that range from fundamental to quantum communication and metrology. Spontaneous four-wave mixing with electromagnetically induced transparency has been demonstrated as one of the most efficient methods; however, narrowing the bandwidth and producing photon pairs with a temporal length beyond 1 μs remains a technical challenge due to noise considerations and the need for cold atoms with a high optical depth (OD). In this work, we demonstrate the generation of narrowband photon pairs with a controllable coherence time up to 1.72 μs in a laser-cooled atomic ensemble with an OD as high as 130. At such a high OD, we find that the pump laser field spatial profile has a significant effect on the time–frequency entangled two-photon waveform. We also confirm the quantum particle nature of heralded narrowband single photons generated from this source.

Optica•Aug 4, 2014•81 citations

Photon pair-state preparation with tailored spectral properties by spontaneous four-wave mixing in photonic-crystal fiber

Karina Garay-Palmett, Hayden McGuinness, Offir Cohen +7 more

We study theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in photonic crystal optical fiber. We show that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications. We focus on the case exhibiting no spectral correlations in the two-photon component of the state, which we call factorability, and which allows heralding of single-photon pure-state wave packets without the need for spectral post filtering. We show that spontaneous four wave mixing exhibits a remarkable flexibility, permitting a wider class of two-photon states, including ultra-broadband, highly-anticorrelated states.

arXiv:0709.3129•Optics Express•Jan 1, 2007•227 citations

Efficient biphoton generation by a waveguide-coupled single atom

Mao-Hua Wang, Xiao-Jun Zhang, M. Artoni +2 more

A single atom undergoing spontaneous four-wave mixing near a chiral waveguide can efficiently channel an emitted Stokes-anti-Stokes photon pair into two tightly confined waveguide modes, yielding thus enhanced biphoton generation without requiring loss suppression or stringent phase matching. We develop a perturbative treatment, valid for a four-level atomic system under experimentally realistic conditions, to explain physical origins and clarify relevant constraints of such an enhancement determined by the interplay of atomic decay rates toward guided and unguided modes. Besides achieving optimal generation rates equivalent to a cold atomic ensemble hundreds of micrometers long in free space, our biphoton source naturally fulfills key requirements for next-generation on-chip quantum light sources, namely low-loss operation, robustness, compactness, and scalability.

quant-pharXiv:2608.30276•Sep 1, 2026•0 citations
We show that narrowband two-color entangled single Stokes photons can be generated in a ultra-cold atoms sample via selective excitation of two spontaneous four-wave mixing (SFWM) processes. Under certain circumstances, the generation, heralded by the respective common anti-Stokes photon, is robust against losses and phase-mismatching and is remarkably efficient owing to balanced resonant enhancement of the two four-wave mixing processes in a regime of combined induced transparency. Maximally color-entangled states can be easily attained by adjusting the detunings of the external couplings and driving fields, even when these are quite weak.
The efficient generation of entanglement is an essential requirement for quantum communications; however, long distances can only be achieved by utilizing entangled states that can be efficiently mapped into matter. Hence, sources generating states with bandwidths naturally compatible with the linewidths of atomic transitions are crucial. We harness the indistinguishability between two spontaneous four-wave mixing processes to achieve the heralded generation of single-photon frequency-bin entangled states. State manipulation admits entanglement and generation probability optimizations yet with negligible absorption. The scheme could also be adapted to photonic and solid interfaces.
Tunable Rydberg interactions in cold atoms can be used to generate strongly correlated photon pairs through a spontaneous four-wave-mixing process in which all driving fields are allowed to work on resonance. The scheme relies on electromagnetically induced transparency and an imbalanced dark state with most atoms trapped in a ground state and a weakly populated Rydberg state. We show in particular that the combination of these two effects results in negligible linear absorption and Raman gain at the Stokes and anti-Stokes frequencies of generated photon pairs, while the nonlocal (Rydberg) nonlinearities contribute significantly to the enhancement of photon-pair generation rates and cross correlations at very low pump strengths and optical depths.
We introduce a new kind of spontaneous four wave mixing process for the generation of photon pairs, in which the four waves involved counter-propagate in a guided-wave medium; we refer to this process as counter-propagating spontaneous four wave mixing (CP-SFWM). We show that for the simplest CP-SFWM source, in which all waves propagate in the same polarization and transverse mode and in which self- and cross-phase modulation effects are negligible, phasematching is attained automatically regardless of dispersion in the fiber or waveguide. Furthermore, we show that in two distinct versions of this source (both pumps pulsed, or one pump pulsed and the remaining one monochromatic), the two-photon state is automatically factorable provided that the length of the nonlinear medium exceeds a certain threshold, easily achievable in practice since this threshold length tends to be in the range of mm to cm. We also show that if one of the pumps approaches the monochromatic limit, and for a sufficient nonlinear medium length, the bandwidth of one of the two photons in a given pair may be reduced to the level of MHz, compatible with electronic transitions for the implementation of atom–photon interfaces, without the use of optical cavities.
The generation of nonclassical photon pairs with a long coherence time is key for applications that range from fundamental to quantum communication and metrology. Spontaneous four-wave mixing with electromagnetically induced transparency has been demonstrated as one of the most efficient methods; however, narrowing the bandwidth and producing photon pairs with a temporal length beyond 1 μs remains a technical challenge due to noise considerations and the need for cold atoms with a high optical depth (OD). In this work, we demonstrate the generation of narrowband photon pairs with a controllable coherence time up to 1.72 μs in a laser-cooled atomic ensemble with an OD as high as 130. At such a high OD, we find that the pump laser field spatial profile has a significant effect on the time–frequency entangled two-photon waveform. We also confirm the quantum particle nature of heralded narrowband single photons generated from this source.
We study theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in photonic crystal optical fiber. We show that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications. We focus on the case exhibiting no spectral correlations in the two-photon component of the state, which we call factorability, and which allows heralding of single-photon pure-state wave packets without the need for spectral post filtering. We show that spontaneous four wave mixing exhibits a remarkable flexibility, permitting a wider class of two-photon states, including ultra-broadband, highly-anticorrelated states.
A single atom undergoing spontaneous four-wave mixing near a chiral waveguide can efficiently channel an emitted Stokes-anti-Stokes photon pair into two tightly confined waveguide modes, yielding thus enhanced biphoton generation without requiring loss suppression or stringent phase matching. We develop a perturbative treatment, valid for a four-level atomic system under experimentally realistic conditions, to explain physical origins and clarify relevant constraints of such an enhancement determined by the interplay of atomic decay rates toward guided and unguided modes. Besides achieving optimal generation rates equivalent to a cold atomic ensemble hundreds of micrometers long in free space, our biphoton source naturally fulfills key requirements for next-generation on-chip quantum light sources, namely low-loss operation, robustness, compactness, and scalability.