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

Physical Review A

Vacuum effects on interference in two-photon down conversion

Z. Y. Ou, L. J. Wang, L. Mandeļ

Published Aug 1, 1989• 102 citations
Publisher

Abstract

A proposed experiment is analyzed theoretically. In the proposed experiment two coherent pump waves fall on two identical nonlinear crystals, down-converted signal and idler beams from the two crystals are mixed by two beam splitters, and the coincidence counting rate for photons leaving the beam splitters is measured. We show that this counting rate depends on the phase difference between the two coherent pump waves, and results from the interference of the vacuum with the down-converted photons. The experiment could be used to look for locality violations along the lines recently proposed by Grangier, Potasek, and Yurke [Phys. Rev. A 38, 3132 (1988)], but without the need for a coherent reference beam for homodyning.

DOI
10.1103/physreva.40.1428

Related papers

Evidence for phase memory in two-photon down conversion through entanglement with the vacuum

Z. Y. Ou, L. J. Wang, X. Y. Zou +1 more

An experiment has been carried out in which two pairs of light beams produced by down conversion in two nonlinear crystals driven by a common pump were mixed by two beam splitters, and the coincidence rate for simultaneous detections of mixed signal and idler photons was measured. It is found that the down-converted light carries information about the phase of the pump field through the entanglement of the down-converted photons with the vacuum.

Physical Review A•Jan 1, 1990•112 citations

Probing the two-photon phase coherence of parametrically down-converted photons by a local oscillator

Masato Koashi, K. Kono, Masaya Matsuoka +1 more

A degenerate beam of down-converted photon pairs from a nonlinear crystal pumped by pulsed light was mixed with coherent local oscillator pulses by a beam splitter, and the coincidence rate for detections of photons at the two output beams was measured. The coincidence rate showed interference fringes as the phase difference between the pump light and the local oscillator was varied. It showed a negative correlation in some range of the phase difference.

Physical Review A•Nov 1, 1994•16 citations

Coherence in two-photon down-conversion induced by a laser

L. J. Wang, X. Y. Zou, L. Mandeļ

Normally, the signal and idler photons produced in the process of parametric down- conversion exhibit no second-order interference. However, in the presence of an external laser beam that follows the path of the signal photon and induces stimulated down-conversions, one would expect coherence to develop between the down-converted signal and idler beams. We have demonstrated the existence of this phenomenon in an experiment with two down-converters pumped by similar pump beams, in which two mutually coherent laser beams followed the paths of the two down-converted signal photons and induced coherence between the two down- converted idler beams. The induced coherence gives rise to observable interference effects, which are presented.

Annual Meeting Optical Society of America•Jan 1, 1990•1 citation

Theory of two-photon down-conversion in the presence of mirrors

Peter W. Milonni, H. Fearn, Anton Zeilinger

A theory of two-photon down-conversion in the presence of mirrors is developed and applied to recent observations of Herzog et al. [Phys. Rev. Lett. 72, 629 (1994)]. The experimentally observed results for counting and coincidence rates as functions of mirror-crystal separations are obtained, and it is shown how the same results may be derived in a simplified formulation that presumes phase-matched signal and idler modes. We account for the observed effects of the finite coherence length of the pump field as well as the signal and idler coherence lengths, which are much shorter than the pump coherence length and have a different physical origin. Our analysis also supports the interpretation of the phenomena observed as being analogous to the modification of single photon spontaneous emission of atoms in cavity QED. \textcopyright{} 1996 The American Physical Society.

Physical Review A•Jun 1, 1996•27 citations

Theory of phase memory in interference between two pairs of downconverted photons

Z. Y. Ou, L. J. Wang, L. Mandeļ

An analysis is presented of the interference between two photon pairs produced in the process of downconversion from two identical crystals, which are then mixed by beam splitters. Because the downconverted photons are entangled with the vacuum, they carry information about the phase of the pump field. As a result the two-photon detection probability is shown to depend on the phase of the pump, even when the resolving time of the detector electronics is far longer than the coherence time of the light.

Annual Meeting Optical Society of America•Jan 1, 1989•0 citations

Complementarity in biphoton generation with stimulated or induced coherence

Axel Heuer, R. W. Menzel, Peter W. Milonni

Coherence can be induced or stimulated in parametric down-conversion using two or three crystals when, for example, the idler modes of the crystals are aligned. Previous experiments with induced coherence [Phys. Rev. Lett. 114, 053601 (2015)] focused on which-path information and the role of vacuum fields in realizing complementarity via reduced visibility in single-photon interference. Here we describe experiments comparing induced and stimulated coherence. Different single-photon interference experiments were performed by blocking one of the pump beams in a three-crystal setup. Each counted photon is emitted from one of two crystals and which-way information may or not be available, depending on the setup. Distinctly different results are obtained in the induced and stimulated cases, especially when a variable transmission filter is inserted between the crystals. A simplified theoretical model accounts for all the experimental results and is also used to address the question of whether the phases of the signal and idler fields in parametric down-conversion are correlated.

arXiv:1506.00457•Physical Review A•Sep 18, 2015•40 citations
A proposed experiment is analyzed theoretically. In the proposed experiment two coherent pump waves fall on two identical nonlinear crystals, down-converted signal and idler beams from the two crystals are mixed by two beam splitters, and the coincidence counting rate for photons leaving the beam splitters is measured. We show that this counting rate depends on the phase difference between the two coherent pump waves, and results from the interference of the vacuum with the down-converted photons. The experiment could be used to look for locality violations along the lines recently proposed by Grangier, Potasek, and Yurke [Phys. Rev. A 38, 3132 (1988)], but without the need for a coherent reference beam for homodyning.
Normally, the signal and idler photons produced in the process of parametric down- conversion exhibit no second-order interference. However, in the presence of an external laser beam that follows the path of the signal photon and induces stimulated down-conversions, one would expect coherence to develop between the down-converted signal and idler beams. We have demonstrated the existence of this phenomenon in an experiment with two down-converters pumped by similar pump beams, in which two mutually coherent laser beams followed the paths of the two down-converted signal photons and induced coherence between the two down- converted idler beams. The induced coherence gives rise to observable interference effects, which are presented.
A theory of two-photon down-conversion in the presence of mirrors is developed and applied to recent observations of Herzog et al. [Phys. Rev. Lett. 72, 629 (1994)]. The experimentally observed results for counting and coincidence rates as functions of mirror-crystal separations are obtained, and it is shown how the same results may be derived in a simplified formulation that presumes phase-matched signal and idler modes. We account for the observed effects of the finite coherence length of the pump field as well as the signal and idler coherence lengths, which are much shorter than the pump coherence length and have a different physical origin. Our analysis also supports the interpretation of the phenomena observed as being analogous to the modification of single photon spontaneous emission of atoms in cavity QED. \textcopyright{} 1996 The American Physical Society.
An analysis is presented of the interference between two photon pairs produced in the process of downconversion from two identical crystals, which are then mixed by beam splitters. Because the downconverted photons are entangled with the vacuum, they carry information about the phase of the pump field. As a result the two-photon detection probability is shown to depend on the phase of the pump, even when the resolving time of the detector electronics is far longer than the coherence time of the light.
Coherence can be induced or stimulated in parametric down-conversion using two or three crystals when, for example, the idler modes of the crystals are aligned. Previous experiments with induced coherence [Phys. Rev. Lett. 114, 053601 (2015)] focused on which-path information and the role of vacuum fields in realizing complementarity via reduced visibility in single-photon interference. Here we describe experiments comparing induced and stimulated coherence. Different single-photon interference experiments were performed by blocking one of the pump beams in a three-crystal setup. Each counted photon is emitted from one of two crystals and which-way information may or not be available, depending on the setup. Distinctly different results are obtained in the induced and stimulated cases, especially when a variable transmission filter is inserted between the crystals. A simplified theoretical model accounts for all the experimental results and is also used to address the question of whether the phases of the signal and idler fields in parametric down-conversion are correlated.