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 Letters

Spectral correlation and interference in non-degenerate photon pairs at telecom wavelengths

Paulina S. Kuo, Thomas Gerrits, Varun Boehm Verma, Sae Woo Nam

Published Oct 27, 2016• 19 citations
Publisher

Abstract

We characterize an entangled-photon-pair source that produces signal and idler photons at 1533 nm and 1567 nm using fiber-assisted signal-photon spectroscopy. By erasing the polarization distinguishability, we observe interference between the two down-conversion paths. The observed interference signature is closely related to the spectral correlations between photons in a Hong-Ou-Mandel interferometer. These measurements suggest good indistinguishability between the two down-conversion paths, which is required for high entanglement visibility.

DOI
10.1364/ol.41.005074

Related papers

Spectral correlation and interference in continuous-wave non-degenerate photon pairs at telecom wavelengths

Paulina S. Kuo, Thomas Gerrits, Varun Boehm Verma +1 more

We have developed an entangled photon pair source based on a domain-engineered, type-II periodically poled lithium niobate crystal that produces signal and idler photons at 1533 nm and 1567 nm. We characterized the spectral correlations of the generated entangled photons using fiber-assisted signal-photon spectroscopy. We observed interference between the two down-conversion paths after erasing polarization distinguishability of the down-converted photons. The observed interference signature is closely related to the spectral correlations between photons in a Hong- Ou-Mandel interferometer. These measurements suggest good indistinguishability between the two downconversion paths, which is required for high entanglement visibility.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 20, 2017•0 citations

Indistinguishability between arbitrary signal and idler photons for scalable quantum networks

Nijil Lal Cheriya Koyyottummal, Ivan A. Burenkov, Paulina S. Kuo +2 more

Two-photon interference, or the indistinguishability of single photons, such as those from spontaneous parametric down-conversion, is required for scalable quantum networks. Here, we study the indistinguishability between signal and idler photons that are not members of the same bi-photon pair, thereby enabling the scalable and interchangeable use of any photon from any of the conjugated paths of down-conversion. We build a Fourier transform-limited source of indistinguishable photons in the telecom C-band that generates identical signal and idler photons distinguished only by polarization. Using a Hong-Ou-Mandel interferometer, we characterize the indistinguishability between signal and idler photons from independent down-conversion events and compare that to the indistinguishable biphotons. Achieving successful two photon interference between signal and idler photons from independent trials enables our source as a modular unit for practical quantum networks.

Quantum Computing, Communication, and Simulation•Mar 19, 2025•0 citations

Poled-fiber source of broadband polarization-entangled photon pairs

E. Y. Zhu, Zhenzhou Tang, Li Qian +7 more

We demonstrate broadband polarization-entangled photon pair generation in a poled fiber phase matched for Type II downconversion in the 1.5 μm telecom band. Even with signal-idler separation greater than 100 nm, we observe fringe visibilities greater than 97% and tangle greater than 0.8. A Hong-Ou-Mandel interference experiment is also used to experimentally confirm the broadband nature of the entanglement.

Optics Letters•Oct 22, 2013•35 citations

An efficient source of frequency anti-correlated entanglement at telecom wavelength

Feiyan Hou, Xiao Xiang, Runai Quan +6 more

We demonstrate an efficient generation of frequency anti-correlated entangled photon pairs at telecom wavelength. The fundamental laser is a continuous-wave high-power fiber laser at 1560 nm, through an extracavity frequency doubling system, a 780-nm pump with a power as high as 742 mW is realized. After single-passing through a periodically poled KTiOPO4 (PPKTP) crystal, degenerate down-converted photon pairs are generated. With an overall detection efficiency of 14.8 %, the count rates of the single photons and coincidence of the photon pairs are measured to be 370 kHz and 22 kHz, respectively. The spectra of the signal and idler photons are centered at 1560.23 and 1560.04 nm, while their 3-dB bandwidths being 3.22 nm both. The joint spectrum of the photon pair is observed to be frequency anti-correlated and have a spectral bandwidth of 0.52 nm. According to the ratio of the single-photon spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 6.19. Based on a Hong–Ou–Mandel interferometric coincidence measurement, a frequency indistinguishability of 95 % is demonstrated. The good agreements with the theoretical estimations show that the inherent extra intensity noise in fiber lasers has little influence on frequency entanglement of the generated photon pairs.

arXiv:1605.01286•Applied Physics B•Apr 27, 2016•15 citations

Integrable optical-fiber source of polarization-entangled photon pairs in the telecom band

Xiaoying Li, Chuang Liang, Kim Fook Lee +3 more

We demonstrate an optical-fiber-based source of polarization-entangled photon pairs with improved quality and efficiency, which has been integrated with off-the-shelf telecom components and is, therefore, well suited for quantum communication applications in the 1550-nm telecom band. Polarization entanglement is produced by simultaneously pumping a loop of standard dispersion-shifted fiber with two orthogonally polarized pump pulses, one propagating in the clockwise and the other in the counterclockwise direction. We characterize this source by investigating two-photon interference between the generated signal-idler photon pairs under various conditions. The experimental parameters are carefully optimized to maximize the generated photon-pair correlation and to minimize contamination of the entangled photon pairs from extraneously scattered background photons that are produced by the pump pulses for two reasons: (i) spontaneous Raman scattering causes uncorrelated photons to be emitted in the signal and idler bands and (ii) broadening of the pump-pulse spectrum due to self-phase modulation causes pump photons to leak into the signal and idler bands. We obtain two-photon interference with visibility $>90%$ without subtracting counts caused by the background photons (only dark counts of the detectors are subtracted), when the mean photon number in the signal (idler) channel is about 0.02/pulse, while no interference is observed in direct detection of either the signal or idler photons.

arXiv:quant-ph/0601087•Physical Review A•May 3, 2006•28 citations

Towards High-Resolution Spectral Correlation Measurements of a Telecom-Band Photon Pair Source

Pranish Shrestha, Jing Su, Anouar Rahmouni +8 more

We present a tool for characterization of photon pair sources, capable of highly-resolved spectral correlation measurements using a two-photon Hong-Ou-Mandel (HOM) interferometer and fiber-based spectrometer with a spectral resolution of less than 20 GHz.

•Jan 1, 2026•0 citations
We characterize an entangled-photon-pair source that produces signal and idler photons at 1533 nm and 1567 nm using fiber-assisted signal-photon spectroscopy. By erasing the polarization distinguishability, we observe interference between the two down-conversion paths. The observed interference signature is closely related to the spectral correlations between photons in a Hong-Ou-Mandel interferometer. These measurements suggest good indistinguishability between the two down-conversion paths, which is required for high entanglement visibility.
We have developed an entangled photon pair source based on a domain-engineered, type-II periodically poled lithium niobate crystal that produces signal and idler photons at 1533 nm and 1567 nm. We characterized the spectral correlations of the generated entangled photons using fiber-assisted signal-photon spectroscopy. We observed interference between the two down-conversion paths after erasing polarization distinguishability of the down-converted photons. The observed interference signature is closely related to the spectral correlations between photons in a Hong- Ou-Mandel interferometer. These measurements suggest good indistinguishability between the two downconversion paths, which is required for high entanglement visibility.
Two-photon interference, or the indistinguishability of single photons, such as those from spontaneous parametric down-conversion, is required for scalable quantum networks. Here, we study the indistinguishability between signal and idler photons that are not members of the same bi-photon pair, thereby enabling the scalable and interchangeable use of any photon from any of the conjugated paths of down-conversion. We build a Fourier transform-limited source of indistinguishable photons in the telecom C-band that generates identical signal and idler photons distinguished only by polarization. Using a Hong-Ou-Mandel interferometer, we characterize the indistinguishability between signal and idler photons from independent down-conversion events and compare that to the indistinguishable biphotons. Achieving successful two photon interference between signal and idler photons from independent trials enables our source as a modular unit for practical quantum networks.
We demonstrate an efficient generation of frequency anti-correlated entangled photon pairs at telecom wavelength. The fundamental laser is a continuous-wave high-power fiber laser at 1560 nm, through an extracavity frequency doubling system, a 780-nm pump with a power as high as 742 mW is realized. After single-passing through a periodically poled KTiOPO4 (PPKTP) crystal, degenerate down-converted photon pairs are generated. With an overall detection efficiency of 14.8 %, the count rates of the single photons and coincidence of the photon pairs are measured to be 370 kHz and 22 kHz, respectively. The spectra of the signal and idler photons are centered at 1560.23 and 1560.04 nm, while their 3-dB bandwidths being 3.22 nm both. The joint spectrum of the photon pair is observed to be frequency anti-correlated and have a spectral bandwidth of 0.52 nm. According to the ratio of the single-photon spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 6.19. Based on a Hong–Ou–Mandel interferometric coincidence measurement, a frequency indistinguishability of 95 % is demonstrated. The good agreements with the theoretical estimations show that the inherent extra intensity noise in fiber lasers has little influence on frequency entanglement of the generated photon pairs.
We demonstrate an optical-fiber-based source of polarization-entangled photon pairs with improved quality and efficiency, which has been integrated with off-the-shelf telecom components and is, therefore, well suited for quantum communication applications in the 1550-nm telecom band. Polarization entanglement is produced by simultaneously pumping a loop of standard dispersion-shifted fiber with two orthogonally polarized pump pulses, one propagating in the clockwise and the other in the counterclockwise direction. We characterize this source by investigating two-photon interference between the generated signal-idler photon pairs under various conditions. The experimental parameters are carefully optimized to maximize the generated photon-pair correlation and to minimize contamination of the entangled photon pairs from extraneously scattered background photons that are produced by the pump pulses for two reasons: (i) spontaneous Raman scattering causes uncorrelated photons to be emitted in the signal and idler bands and (ii) broadening of the pump-pulse spectrum due to self-phase modulation causes pump photons to leak into the signal and idler bands. We obtain two-photon interference with visibility >90>90%>90 without subtracting counts caused by the background photons (only dark counts of the detectors are subtracted), when the mean photon number in the signal (idler) channel is about 0.02/pulse, while no interference is observed in direct detection of either the signal or idler photons.