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/0304105 · Physical Review A

Quantum interference with beamlike type-II spontaneous parametric down-conversion

Yoon-Ho Kim

Published Jul 2, 2003• 49 citations
arXivHTMLPDF

Abstract

We implement experimentally methods to generate photon-number--path and polarization entangled photon pairs using ``beamlike'' type-II spontaneous parametric down-conversion, in which the signal-idler photon pairs are emitted as two separate circular beams with small emission angles rather than as two diverging cones.
DOI
10.1103/physreva.68.013804

Related papers

Quantum interference with beamlike type-II spontaneous parametric down-conversion

Yoon-Ho Kim

We implement experimentally a method to generate photon-number−path and polarization entangled photon pairs using “beamlike” type-II spontaneous parametric down-conversion (SPDC), in which the signal-idler photon pairs are emitted as two separate circular beams with small emission angles rather than as two diverging cones.

Conference on Lasers and Electro-Optics•Jan 1, 2004•3 citations

Beamlike photon-pair generation for two-photon interference and polarization entanglement

Hsin-Pin Lo, Atsushi Yabushita, Chih‐Wei Luo +2 more

Beamlike photon pairs were generated by spontaneous parametric down-conversion using a type-II $\ensuremath{\beta}$-BaB${}_{2}$O${}_{4}$ crystal. A pump laser generated photon pairs when it transmitted through the crystal and was reflected back into the crystal by a mirror to generate more photon pairs. The photon pairs generated when the pump laser first transmitted through the crystal (first photon pairs) were also reflected back into the crystal to overlap with the light path of the photon pairs generated in the second transmission of the pump laser through the crystal (second photon pairs). We observed interference between the first and second photon pairs modulated with a half period of the wavelength of the photon pairs, which demonstrates two-photon interference using the beamlike photon pairs. The fringe period confirms that the observed interference is not classical interference but quantum two-photon interference. Through rotating the angles of quarter-wave plates in the light paths of the photon pairs, we generated beamlike photon pairs with entangled polarization. The phase between the first and second photon pairs could be tuned by changing the position of mirrors reflecting the pump pulses and photon pairs. The fringes of coincidence counts showed that the beamlike photon pairs have polarization entanglement.

Physical Review A•Feb 14, 2011•7 citations

Beamlike Photon-Pair Generation for Two-Photon Interference and Polarization Entanglement

Takayoshi Kobayashi

Beamlike photon pairs were generated by spontaneous parametric down-conversion using a type-II β-BaB 2 O 4 crystal. A pump laser generated photon pairs when it was transmitted through the crystal and was reflected back into the crystal by a mirror to generate more photon pairs. The photon pairs generated when the pump laser first transmitted through the crystal (first photon pairs) were also reflected back into the crystal to overlap with the light path of the photon pairs generated in the second transmission of the pump laser through the crystal (second photon pairs). We observed interference between the first and second photon pairs modulated with a half period of the wavelength of the photon pairs, which demonstrates two-photon interference using the beamlike photon pairs. The fringe period confirms that the observed interference is not classical interference but quantum two-photon interference. Through rotating the angles of quarter-wave plates in the light paths of the photon pairs, we generated beamlike photon pairs with entangled polarization. The phase between the first and second photon pairs could be tuned by changing the position of mirrors reflecting the pump pulses and photon pairs. The fringes of coincidence counts showed that the beamlike photon pairs have polarization entanglement.

CRC Press eBooks•Oct 15, 2025•0 citations

Beamlike photon-pair generation for two-photon interference and polarization entanglement

Hsin-Pin Lo, Atsushi Yabushita, Chih‐Wei Luo +2 more

Beamlike photon pairs were generated by SPDC using a type-II BBO crystal. The interference between the first and second photon pairs of coincidence counts showed that the beamlike photon pairs have polarization entanglement.

International Conference on Quantum Information•Jan 1, 2011•1 citation

Beamlike twin-photon generation by use of type II parametric downconversion

Shigeki Takeuchi

Beamlike twin-photon generation by use of type II spontaneous parametric downconversion is demonstrated. The intensity distribution of each beam is round, and the emission angle is very small (0.9 degrees ). As a result, a high coincidence-count rate per unit of pump power was recorded. The ratio of coincidence-count rate to single-count rate was estimated to be 80% in this experiment. These features suggest that this method is useful for generation of a single-photon state and is applicable to bright, entangled twin-photon sources.

Optics Letters•Jun 1, 2001•105 citations

Beamlike Photon Pairs Entangled by a 2 × 2 Fiber

Takayoshi Kobayashi

Polarization-entangled photon pairs have been widely used as a light source for quantum communication. The polarization-entangled photon pairs are generally obtained at the crossing points of the light cones that are generated from a type-II nonlinear crystal. However, it is hard to pick up the photon pairs coming out from the crossing points because of their invisible wavelength and low intensity. In our previous work, we succeeded in generating polarization-entangled photon pairs by overlapping two light paths for the photon-pair generation. The photon pairs could be entangled in all of the generated photon pairs without clipping the crossing points, even with some difficulty in their alignment to overlap the two light paths. In this paper, we have developed an optical system that generates polarization-entangled photon pairs using a beamlike photon pair, without the difficulty in alignment. The measured results show that the photon pairs generated in the system are entangled in their polarizations.

CRC Press eBooks•Oct 15, 2025•0 citations
Beamlike photon pairs were generated by spontaneous parametric down-conversion using a type-II $\ensuremath{\beta}$-BaB2{}_{2}2​O4{}_{4}4​ crystal. A pump laser generated photon pairs when it transmitted through the crystal and was reflected back into the crystal by a mirror to generate more photon pairs. The photon pairs generated when the pump laser first transmitted through the crystal (first photon pairs) were also reflected back into the crystal to overlap with the light path of the photon pairs generated in the second transmission of the pump laser through the crystal (second photon pairs). We observed interference between the first and second photon pairs modulated with a half period of the wavelength of the photon pairs, which demonstrates two-photon interference using the beamlike photon pairs. The fringe period confirms that the observed interference is not classical interference but quantum two-photon interference. Through rotating the angles of quarter-wave plates in the light paths of the photon pairs, we generated beamlike photon pairs with entangled polarization. The phase between the first and second photon pairs could be tuned by changing the position of mirrors reflecting the pump pulses and photon pairs. The fringes of coincidence counts showed that the beamlike photon pairs have polarization entanglement.
Beamlike photon pairs were generated by spontaneous parametric down-conversion using a type-II β-BaB 2 O 4 crystal. A pump laser generated photon pairs when it was transmitted through the crystal and was reflected back into the crystal by a mirror to generate more photon pairs. The photon pairs generated when the pump laser first transmitted through the crystal (first photon pairs) were also reflected back into the crystal to overlap with the light path of the photon pairs generated in the second transmission of the pump laser through the crystal (second photon pairs). We observed interference between the first and second photon pairs modulated with a half period of the wavelength of the photon pairs, which demonstrates two-photon interference using the beamlike photon pairs. The fringe period confirms that the observed interference is not classical interference but quantum two-photon interference. Through rotating the angles of quarter-wave plates in the light paths of the photon pairs, we generated beamlike photon pairs with entangled polarization. The phase between the first and second photon pairs could be tuned by changing the position of mirrors reflecting the pump pulses and photon pairs. The fringes of coincidence counts showed that the beamlike photon pairs have polarization entanglement.
Beamlike twin-photon generation by use of type II spontaneous parametric downconversion is demonstrated. The intensity distribution of each beam is round, and the emission angle is very small (0.9 degrees ). As a result, a high coincidence-count rate per unit of pump power was recorded. The ratio of coincidence-count rate to single-count rate was estimated to be 80% in this experiment. These features suggest that this method is useful for generation of a single-photon state and is applicable to bright, entangled twin-photon sources.
Polarization-entangled photon pairs have been widely used as a light source for quantum communication. The polarization-entangled photon pairs are generally obtained at the crossing points of the light cones that are generated from a type-II nonlinear crystal. However, it is hard to pick up the photon pairs coming out from the crossing points because of their invisible wavelength and low intensity. In our previous work, we succeeded in generating polarization-entangled photon pairs by overlapping two light paths for the photon-pair generation. The photon pairs could be entangled in all of the generated photon pairs without clipping the crossing points, even with some difficulty in their alignment to overlap the two light paths. In this paper, we have developed an optical system that generates polarization-entangled photon pairs using a beamlike photon pair, without the difficulty in alignment. The measured results show that the photon pairs generated in the system are entangled in their polarizations.