2019/12/31 by Yiquan Yang, Peiyu Zhang, Xiao-Song Ma +1
Computer Science · Physics and Astronomy · #Atomic and Subatomic Physics Research #Optics #Photon #Physics #Quantum Information and Cryptography #Quantum Mechanics and Applications #Tomography #physics.optics #quant-ph
paper · pdf · doi:10.1364/josab.397457
published as J. Opt. Soc. Am. B 37, 2071-2075 (2020) · 7 pages, 3 figures
openalex created_date 2019/12/26 · openalex publication_date 2020/06/01 · arxiv created 2021/01/26 · arxiv updated 2021/01/27 · openalex updated_date 2026/08/05
Frequency nondegenerate entangled photon pairs have been employed in quantum communication, imaging, and sensing. To characterize quantum entangled states with long-wavelength [infrared (IR) or even terahertz (THz)] photons, one needs to either develop the single-photon detectors at the corresponding wavelengths or use a novel tomography technique that does not rely on single-photon detections, such as stimulated emission tomography (SET). We use standard quantum state tomography and SET to measure the density matrix of entangled photon pairs, with one photon at 1550 nm and the other one at 810 nm, and obtain highly consistent results, showing the reliability of SET. Our work paves the way for efficient measurement of entangled photons with highly dissimilar frequencies, even to the frequencies where single-photon detections are not available.