2014/12/12 by Lee A. Rozema, Rozema, Lee A., Chao Wang +11
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Cold Atom Physics and Bose-Einstein Condensates #Quantum Mechanics and Applications
paper · pdf · doi:10.48550/arxiv.1412.4134
Quantum state tomography (QST) is a universal tool for the design and\noptimization of entangled-photon sources. It typically requires single-photon\ndetectors and coincidence measurements. Recently, it was suggested that the\ninformation provided by the QST of photon pairs generated by spontaneous\nparametric down-conversion could be obtained by exploiting the stimulated\nversion of this process, namely difference frequency generation. In this\nprotocol, so-called "stimulated-emission tomography" (SET), a seed field is\ninjected along with the pump pulse, and the resulting stimulated emission is\nmeasured. Since the intensity of the stimulated field can be several orders of\nmagnitude larger than the intensity of the corresponding spontaneous emission,\nmeasurements can be made with simple classical detectors. Here, we\nexperimentally demonstrate SET and compare it with QST. We show that one can\naccurately reconstruct the polarization density matrix, and predict the purity\nand concurrence of the polarization state of photon pairs without performing\nany single-photon measurements.\n