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Quantum 2.0 Conference and Exhibition

Approaching Mega-Scale Quantum Detector Tomography using High-Performance Computing

Timon Schapeler, Michael Lass, Christian Plessl, Tim J. Bartley

Published Jan 1, 2023• 0 citations
Publisher

Abstract

Quantum characterization tools must keep up with the ever-increasing size of detector arrays for quantum applications. We show quantum detector tomography per-formed on a supercomputer which reconstructs the POVMs up to 2.5 · 105 photons.
DOI
10.1364/quantum.2023.qw4c.6

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Photon counting is a cornerstone of quantum optics. Here, we demonstrate precisely counting from 0 to over 9000 photons, beating the Poisson noise limit by at least 4.1 dB4.1~\mathrm{dB}4.1 dB across this range. We achieve sub-single-photon precision up to 276 photons per pulse. To do so, we multiplex eight intrinsically photon-number-resolving superconducting nanowire single-photon detectors across 128 temporal modes. We use a model-informed characterization of each of the 1024 detection bins, for optimal precision. We perform quantum detector tomography to reconstruct the positive operator valued measures (POVMs) of the complete device, which consists of 1.38⋅1081.38\cdot10^81.38⋅108 matrix elements. At the repetition rate of our experiment of 80 kHz80~\mathrm{kHz}80 kHz, we can precisely count photons corresponding to an optical power of approximately 71 pW71~\mathrm{pW}71 pW, bridging the gap from single-photon measurements to high-sensitivity optical power meters. A photon-number-resolving detector of this size, and the tools used to analyze it, will become increasingly important to characterize large quantum states, as well as tasks in precision metrology and optical power standards.