Broadband frequency-entangled photons for novel quantum nonlinear optics

Ryōsuke Shimizu

Yuanhua Li, Yiwen Huang, Zhantong Qi +1 more

Abstract Coherent correlation between two distant broadband single photons can be realized by using the nonlinear optical method, which provides a key technology for spread‐spectrum communication in the quantum network. Here, sum‐frequency generation (SFG) between two broadband single photons is experimentally demonstrated by using chirp technology. The results show that the efficiency of the SFG is 6.51 × 10 −8 , and the visibility of coherent correlation of two distant broadband photons of the telecommunications band is 93.7%. This technique can also be used for other quantum applications, such as quantum entanglement swapping and quantum communication.

Mikhail D. Lukin, Imamoglu

Masayuki Okano, Ryo Okamoto, Akira Tanaka +4 more

Optical coherence tomography (OCT) based on Michelson interferometer has widely been utilized in biology and medicine as a type of optical biopsy and quantum optical coherence tomography (QOCT) based on Hong-Ou-Mandel interferometer has recently been demonstrated. By use of quantum entangled photon pairs generated via spontaneous parametric down conversion (SPDC) process, axial resolution of QOCT can be better than that of OCT in principle for a source of same bandwidth and group velocity dispersion (GVD) effect for QOCT can be automatically cancelled thanks to the frequency correlation of entangled photon pairs. To realize high-resolution QOCT, we need a broadband quantum entangled photon pair source. Then we proposed a novel conventional method to generate broadband spontaneous parametric fluorescence via SPDC by using multiple nonlinear crystals pumped by a CW laser. Our method has controllability to tune the center frequency of generated photons and scalability to extend the number of crystals. This conventional method can enable us to achieve sub-micron axial resolution of QOCT.

Zhenghao Yin, Kenta Sugiura, Xiaoyang Cheng +4 more

Quantum entanglement in chip scale has been attracting the recent research interests. With the standard CMOS technology, it is possible to realize entangled photon sources in optical nonlinear micro ring resonators on the platform of silicon[1] or silicon nitride[3]. In order to extend the frequency entanglement range, i.e., to satisfy a broadband phase matching condition, it is essential to take the group velocity dispersion (GVD) into consideration during the four wave mixing process.

Vincenzo Macr `i, Anton Frisk Kockum, Roberto Stassi +3 more