# Generation of polarization-entangled photon pairs in a cascade of two type-I crystals pumped by femtosecond pulses

Source: [Generation of polarization-entangled photon pairs in a cascade of two type-I crystals pumped by femtosecond pulses](<https://www.sota2.com/research/paper/68fa25f32c2a3760193b546a>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T11:04:48.651Z

Authors: Y. Nambu, K. Usami, Y. Tsuda, K. Matsumoto, K. Nakamura

Published: 2002-03-22T10:06:30.000Z

## Abstract

We report the generation of polarization-entangled photons by femtosecond-pulse-pumped spontaneous parametric down-conversion in a cascade of two type-I crystals. Highly entangled pulsed states were obtained by introducing a temporal delay between the two orthogonal polarization components of the pump field. They exhibited high-visibility quantum interference and a large concurrence value, without the need of post-selection using narrow-bandwidth-spectral filters. The results are well explained by the theory which incorporates the space-time dependence of interfering two-photon amplitudes if dispersion and birefringence in the crystals are appropriately taken into account. Such a pulsed entangled photon well localized in time domain is useful for various quantum communication experiments, such as quantum cryptography and quantum teleportation.

## Recorded benchmark results

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/quant-ph/0203115>)

[PDF](<https://arxiv.org/pdf/quant-ph/0203115.pdf>)