Quantum circuits with many photons on a programmable nanophotonic chip

• Published in: Nature (London) Vol. 591; no. 7848; pp. 54 - 60
• Main Authors: Arrazola, J. M., Bergholm, V., Brádler, K., Bromley, T. R., Collins, M. J., Dhand, I., Fumagalli, A., Gerrits, T., Goussev, A., Helt, L. G., Hundal, J., Isacsson, T., Israel, R. B., Izaac, J., Jahangiri, S., Janik, R., Killoran, N., Kumar, S. P., Lavoie, J., Lita, A. E., Mahler, D. H., Menotti, M., Morrison, B., Nam, S. W., Neuhaus, L., Qi, H. Y., Quesada, N., Repingon, A., Sabapathy, K. K., Schuld, M., Su, D., Swinarton, J., Száva, A., Tan, K., Tan, P., Vaidya, V. D., Vernon, Z., Zabaneh, Z., Zhang, Y.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.03.2021; Nature Publishing Group
• Subjects: 639/624/400/482; 639/766/1130/2799; 639/766/483/481; Algorithms; Application programming interface; Automatic control; Automation; Circuits; Control systems; Data processing; Experiments; Humanities and Social Sciences; Information processing; Interferometers; Launching pads; Light; multidisciplinary; Photonics; Photons; Quantum computing; Quantum phenomena; Room temperature; Sampling; Science; Science (multidisciplinary); Sequences; Silicon nitride; Software; Squeezed states (quantum theory)
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-021-03202-1

Growing interest in quantum computing for practical applications has led to a surge in the availability of programmable machines for executing quantum algorithms 1 , 2 . Present-day photonic quantum computers 3 – 7 have been limited either to non-deterministic operation, low photon numbers and rates, or fixed random gate sequences. Here we introduce a full-stack hardware−software system for executing many-photon quantum circuit operations using integrated nanophotonics: a programmable chip, operating at room temperature and interfaced with a fully automated control system. The system enables remote users to execute quantum algorithms that require up to eight modes of strongly squeezed vacuum initialized as two-mode squeezed states in single temporal modes, a fully general and programmable four-mode interferometer, and photon number-resolving readout on all outputs. Detection of multi-photon events with photon numbers and rates exceeding any previous programmable quantum optical demonstration is made possible by strong squeezing and high sampling rates. We verify the non-classicality of the device output, and use the platform to carry out proof-of-principle demonstrations of three quantum algorithms: Gaussian boson sampling, molecular vibronic spectra and graph similarity 8 . These demonstrations validate the platform as a launchpad for scaling photonic technologies for quantum information processing. A system for realizing many-photon quantum circuits is presented, comprising a programmable nanophotonic chip operating at room temperature, interfaced with a fully automated control system.