• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.308-313
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• 2002

One of the nonclassical effects in two-photon interference experiments, spatial quantum beating, is observed in fourth-order interference with pairs of photons produced by a spontaneous parametric down-conversion process. When photon pairs in different frequencies $\omega1$ and $\omega2$ are mixed together, and directed to two detectors, the coincidence counts exhibit a cosine modulation with difference frequency | $\omega1$- $\omega2$|. The measured coincidence counts turned out to have an interference pattern with periodicity of 10.45 ㎛ in position or 34.82fs in time delay, which corresponds to the period 2$\pi$/| $\omega1$- $\omega2$| for the beat frequency of 0.29${\times}10^{14}$Hz.

• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.99-112
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• 2019

A quantum light source is an essential element for quantum information technology, including quantum communication, quantum sensor, and quantum computer. Quantum light sources including photon number state, entangled state, and squeezed state can be divided into two types according to the generation mechanism, namely single emitter and non-linear based systems. The single emitter platform contains atom/ion trap, solid-state defect/color center, two-dimensional material, and semiconductor quantum dot, which can emit deterministic photons. The non-linear based platform contains spontaneous parametric down-conversion and spontaneous four-wave mixing, which can emit probabilistic photon pairs. For each platform, we give an overview of the recent research trends of the generation, manipulation, and integration of single photon and entangled photon sources. The characteristics of quantum light sources are investigated for each platform. In addition, we briefly introduce quantum sensing, quantum communication, and quantum computing applications based on quantum light sources. We discuss the challenges and prospects of quantum light sources for quantum information technology.

• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.276-282
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• 2011

We performed experiments on Hong-Ou-Mandel type two-photon interference with frequency entangled photon pairs at 1.5 ${\mu}m$ telecommunication band generated through femtosecond pulsed spontaneous parametric down-conversion. Two different angular frequencies ${\omega}_1$ and ${\omega}_2$ were selected using CWDM(coarse wavelength division multiplexing) filters at the output ports of the interferometer. The coincidence counting rates were measured with varying path-length difference between the two interferometer arms to observe the two-photon interference patterns of spatial beating. The obtained visibilities in the net coincidence were close to the theoretical limit of 100%.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.116-121
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• 2003

We have observed a nonclassical effect in a fourth-order interference experiment with the photon pairs produced by parametric down-conversion and the Hong-Ou-Handel interferometer. For interfering classical fields with orthogonal polarizations, the visibility can be no larger than 50%, and it depends on the ratio of the two beam intensities. It is found that not only is our observed visibility of 85％ well above 50％, but it is also independent of the two beam intensities in coincidence measurements made in a two-photon polarization correlation experiment.