Large-inductance superconducting microstrip photon detector enabling 10 photon-number resolution

Large-inductance superconducting microstrip photon detector enabling 10 photon-number resolution

Jan/Feb 2024 | Ling-Dong Kong, Tian-Zhu Zhang, Xiao-Yu Liu, Hao Li, Zhen Wang, Xiao-Ming Xie and Li-Xing You
The authors present a large-inductance superconducting microstrip photon detector (SMSPD) that achieves 10 true photon-number resolution with readout fidelities of 98% and 90% for 4-photon and 6-photon events, respectively. The SMSPD's design includes a meandering microstrip with optimized sections for detection, connection, and bending, resulting in high current density in the detection section. The detector's performance is enhanced by increasing the total inductance and strip width, which stretches the rising edges of the electrical pulses, improving photon-number discrimination. A dual-channel timing setup reduces data acquisition by three orders of magnitude, enabling real-time photon-number readout. The system is demonstrated in a quantum random-number generator (QRNG) based on sampling the parity of a coherent state, showing inherent unbiasedness, robustness against experimental imperfections and environmental noise, and invulnerability to eavesdropping. The SMSPD's high fidelity, large dynamic range, and real-time characterization make it a promising tool for optical quantum information science.The authors present a large-inductance superconducting microstrip photon detector (SMSPD) that achieves 10 true photon-number resolution with readout fidelities of 98% and 90% for 4-photon and 6-photon events, respectively. The SMSPD's design includes a meandering microstrip with optimized sections for detection, connection, and bending, resulting in high current density in the detection section. The detector's performance is enhanced by increasing the total inductance and strip width, which stretches the rising edges of the electrical pulses, improving photon-number discrimination. A dual-channel timing setup reduces data acquisition by three orders of magnitude, enabling real-time photon-number readout. The system is demonstrated in a quantum random-number generator (QRNG) based on sampling the parity of a coherent state, showing inherent unbiasedness, robustness against experimental imperfections and environmental noise, and invulnerability to eavesdropping. The SMSPD's high fidelity, large dynamic range, and real-time characterization make it a promising tool for optical quantum information science.
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