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

Lithuanian Journal of Physics

Photon correlation and statistics of spontaneous parametric down-conversion pumped by blue LED in LiIO3 crystal

Justinas Galinis, Michał Karpiński, G. Tamošauskas, Krzysztof Dobek, A. Piskarskas

Published Jan 1, 2012• 3 citations
Publisher

Abstract

We report on the measurement of photon coincidence and photon number statistics of the spontaneous parametric down-converted radiation excited by incoherent pump. A high ratio of photon coincidences in case of multimode acquisition suggests that the present technique may find application in quantum experiments. Experimental and numerical simulation results confirmed that the coincidence ratio in a photon counting experiment is tightly coupled to the coherence of the pump beam. An experiment on verification of statistical properties of the down-converted radiation allowed us to evaluate the afterpulse generation probability of the photon counters.

DOI
10.3952/lithjphys.52401

Related papers

Photon coincidences in spontaneous parametric down-converted radiation excited by a blue LED in bulk LiIO_3 crystal

Justinas Galinis, Michał Karpiński, G. Tamošauskas +2 more

We report on experimental and numerical investigation of two-photon coincidence properties of the parametric spontaneous down-converted field excited by a high brightness blue LED in bulk lithium iodate crystal. Ratio of up to 11.5% of coincidence, which cannot be attributed to classical coincidences, to single photon counts was recorded at the outputs of multimode fibers, demonstrating well-preserved biphoton property. This result, combined with practically useful power of the source, suggests its possible application for a class of quantum experiments.

Optics Express•May 11, 2011•13 citations

Coherence properties of entangled light beams generated by parametric down-conversion: Theory and experiment

Adel Joobeur, Bahaa E. A. Saleh, Todd S. Larchuk +1 more

Using a multidimensional Gaussian approximation of the wave function for the signal and idler light generated by spontaneous parametric down-conversion, we derive analytical expressions for the second-order coherence function and the fourth-order coherence function (which is proportional to the signal-idler photon coincidence rate). The magnitudes of these functions are expressed as products of Gaussian functions of the azimuthal angles, the polar angles, and the time delay. Their widths determine six parameters: the coherence angles and coherence time, and the entanglement angles and entanglement time. We show how these parameters are governed by the pump-beam waist, the pump spectral width, and the crystal length. We thereby derive relations analogous to the van Cittert--Zernike theorem and the Siegert relation for thermal light. We show that the normalized photon coincidence rate decreases sharply as the signal and idler apertures become mismatched or misaligned. We experimentally confirm this latter prediction by using parametrically down-converted light obtained from a ${\mathrm{LiIO}}_{3}$ crystal pumped by ${\mathrm{Kr}}^{+}$-ion laser radiation at 413 nm. \textcopyright{}1996 The American Physical Society.

Physical Review A•Jun 1, 1996•126 citations

Transverse coherence of photon pairs generated in spontaneous parametric down-conversion

Martin Hamar, Jan Peřina, Ondřej Haderka +1 more

Coherence properties of the down-converted beams generated in spontaneous parametric down-conversion are investigated in detail using an iCCD camera. Experimental results are compared with those from a theoretical model developed for pulsed pumping with a Gaussian transverse profile. The results allow us to tailor the shape of correlation area of the signal and idler photons using pump-field and crystal parameters. As an example, splitting of a correlation area caused by a two-peak pump-field spectrum is experimentally studied.

arXiv:1003.1249•Physical Review A•Apr 21, 2010•45 citations

Influence of pump coherence on the quantum properties of spontaneous parametric down-conversion

Giese, Enno, Fickler, Robert, Zhang, Wuhong +2 more

The correlation properties of the pump field in spontaneous parametric down-conversion are crucial in determining the degree of entanglement of generated signal and idler photons. We find theoretically that continuous-variable entanglement of the transverse positions and momenta of these photons can be achieved only if the coherence of the pump beam is sufficiently high. The positions of signal and idler photons are found to be correlated, even for an incoherent pump. However, the momenta of the signal and idler photons are not anti-correlated, even though transverse momentum is conserved.

•Jan 1, 2018•0 citations

Photon extrabunching in ultrabright twin beams measured by two-photon counting in a semiconductor

Fabien Boitier, Antoine Godard, N. Dubreuil +3 more

For many years twin beams originating from parametric down-converted light beams have aroused great interest and attention in the photonics community. One particular aspect of the twin beams is their peculiar intensity correlation functions, which are related to the coincidence rate of photon pairs. Here we take advantage of the huge bandwidth offered by two-photon absorption in a semiconductor to quantitatively determine correlation functions of twin beams generated by spontaneous parametric down-conversion. Compared with classical incoherent sources, photon extrabunching is unambiguously and precisely measured, originating from exact coincidence between down-converted pairs of photons, travelling in unison. These results strongly establish that two-photon counting in semiconductors is a powerful tool for the absolute measurement of light beam photon correlations at ultrashort timescales. The second order correlation functiong(2) is used to test quantum correlation properties of light. Here, two-photon counting is used to measure g(2)and an extrabunching effect is demonstrated, providing evidence that two-photon counting is an appropriate method for measuring light beam photon correlations.

Nature Communications•Aug 9, 2011•73 citations

Photon statistic measurement of down-converted light

Dániel Oszetzky, A. Czitrovsky

Taking advantage of our previous experimental results and calculations that establish a new approach to the calibration of photo detectors using correlated photon pairs, we developed an experimental setup with a fast electronic control unit for the direct measurement of photon statistics. The most convenient source for generating such correlated photon pairs is a nonlinear optical process of spontaneous parametric down conversion (SPDC). When a photon of the pump beam is incident to a nonlinear crystal with phase matching condition, a pair of photons (signal and idler) is created at the same time. The photons are detected in the signal beam, and a controllable shutter is placed in the idler beam. When a detection event is made in the signal beam the fast optical shutter opens for a certain (pre-programmed) time. While the opening time of the shutter is adjustable with good time resolution, the time interval between the photons in the idler beam can be scanned, so the photon statistics can be determined.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jan 19, 2006•1 citation
We report on the measurement of photon coincidence and photon number statistics of the spontaneous parametric down-converted radiation excited by incoherent pump. A high ratio of photon coincidences in case of multimode acquisition suggests that the present technique may find application in quantum experiments. Experimental and numerical simulation results confirmed that the coincidence ratio in a photon counting experiment is tightly coupled to the coherence of the pump beam. An experiment on verification of statistical properties of the down-converted radiation allowed us to evaluate the afterpulse generation probability of the photon counters.
We report on experimental and numerical investigation of two-photon coincidence properties of the parametric spontaneous down-converted field excited by a high brightness blue LED in bulk lithium iodate crystal. Ratio of up to 11.5% of coincidence, which cannot be attributed to classical coincidences, to single photon counts was recorded at the outputs of multimode fibers, demonstrating well-preserved biphoton property. This result, combined with practically useful power of the source, suggests its possible application for a class of quantum experiments.
Using a multidimensional Gaussian approximation of the wave function for the signal and idler light generated by spontaneous parametric down-conversion, we derive analytical expressions for the second-order coherence function and the fourth-order coherence function (which is proportional to the signal-idler photon coincidence rate). The magnitudes of these functions are expressed as products of Gaussian functions of the azimuthal angles, the polar angles, and the time delay. Their widths determine six parameters: the coherence angles and coherence time, and the entanglement angles and entanglement time. We show how these parameters are governed by the pump-beam waist, the pump spectral width, and the crystal length. We thereby derive relations analogous to the van Cittert--Zernike theorem and the Siegert relation for thermal light. We show that the normalized photon coincidence rate decreases sharply as the signal and idler apertures become mismatched or misaligned. We experimentally confirm this latter prediction by using parametrically down-converted light obtained from a LiIO3{\mathrm{LiIO}}_{3}LiIO3​ crystal pumped by Kr+{\mathrm{Kr}}^{+}Kr+-ion laser radiation at 413 nm. \textcopyright{}1996 The American Physical Society.
Coherence properties of the down-converted beams generated in spontaneous parametric down-conversion are investigated in detail using an iCCD camera. Experimental results are compared with those from a theoretical model developed for pulsed pumping with a Gaussian transverse profile. The results allow us to tailor the shape of correlation area of the signal and idler photons using pump-field and crystal parameters. As an example, splitting of a correlation area caused by a two-peak pump-field spectrum is experimentally studied.
The correlation properties of the pump field in spontaneous parametric down-conversion are crucial in determining the degree of entanglement of generated signal and idler photons. We find theoretically that continuous-variable entanglement of the transverse positions and momenta of these photons can be achieved only if the coherence of the pump beam is sufficiently high. The positions of signal and idler photons are found to be correlated, even for an incoherent pump. However, the momenta of the signal and idler photons are not anti-correlated, even though transverse momentum is conserved.
For many years twin beams originating from parametric down-converted light beams have aroused great interest and attention in the photonics community. One particular aspect of the twin beams is their peculiar intensity correlation functions, which are related to the coincidence rate of photon pairs. Here we take advantage of the huge bandwidth offered by two-photon absorption in a semiconductor to quantitatively determine correlation functions of twin beams generated by spontaneous parametric down-conversion. Compared with classical incoherent sources, photon extrabunching is unambiguously and precisely measured, originating from exact coincidence between down-converted pairs of photons, travelling in unison. These results strongly establish that two-photon counting in semiconductors is a powerful tool for the absolute measurement of light beam photon correlations at ultrashort timescales. The second order correlation functiong(2) is used to test quantum correlation properties of light. Here, two-photon counting is used to measure g(2)and an extrabunching effect is demonstrated, providing evidence that two-photon counting is an appropriate method for measuring light beam photon correlations.
Taking advantage of our previous experimental results and calculations that establish a new approach to the calibration of photo detectors using correlated photon pairs, we developed an experimental setup with a fast electronic control unit for the direct measurement of photon statistics. The most convenient source for generating such correlated photon pairs is a nonlinear optical process of spontaneous parametric down conversion (SPDC). When a photon of the pump beam is incident to a nonlinear crystal with phase matching condition, a pair of photons (signal and idler) is created at the same time. The photons are detected in the signal beam, and a controllable shutter is placed in the idler beam. When a detection event is made in the signal beam the fast optical shutter opens for a certain (pre-programmed) time. While the opening time of the shutter is adjustable with good time resolution, the time interval between the photons in the idler beam can be scanned, so the photon statistics can be determined.