Design for reducing dark count of SNSPD based on double-line structure

Abstract

The invention discloses a design for reducing dark count of an SNSPD based on a double-wire structure. The design comprises the steps of enabling two niobium nitride nanowires to be wound with each other in a non-crossed manner to form a superconducting nanowire single-photon detector SNSPD with the double-wire structure, regulating the behavior of the other nanowire through one nanowire, and adjusting a bias current to be close to a superconducting critical current; introducing an optical signal into a photosensitive area of the detector by adopting an optical fiber, and respectively outputting two paths of signals through two nanowires, so that dark counts between the two nanowires are mutually excited, the dark count signals are reduced through a voltage comparator and an exclusive-OR gate, and a photon response signal is reserved. By using the unique performance of the SNSPD with the double-wire structure, the dark count of the detector can be effectively inhibited, the coupling efficiency of the dark count of the SNSPD is further improved through process improvement in the later period, the dark count of the SNSPD system is expected to be completely inhibited, and the signal-to-noise ratio of the detector is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of superconducting single photon detection, and in particular relates to a dark count subtraction technology. Background technique [0002] Superconducting nanowire single photon detector (SNSPD) is a new type of photodetector for efficient, fast and accurate detection of single photons. The photosensitive part is a nanowire meander structure made of superconducting thin film materials. [0003] When the detector is working, it is biased at a position slightly lower than its superconducting critical current. When the nanowire absorbs photons, the superconducting state in the absorbing region is destroyed, resulting in a heat island. The heat island region grows with the assistance of current Joule heat. To a certain range, after the cooling of the nanowire itself and the substrate, the heat island disappears, and the nanowire returns to its initial state. [0004] The process of photon absorption by the det...

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Problems solved by technology

[0008] For background radiation dark counting, the commonly used method is to use fiber optic filter at low temperature to eliminate background radiation, but for intrinsic dark counting, there is no better general method so far.

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