Operation of a Superconducting Nanowire in Two Detection Modes: KID and SPD

Edward Schroeder, Philip Mauskopf, Hamdi Mani, Sean Bryan, Karl K. Berggren, Di Zhu

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We present the performance of a superconducting nanowire that can be operated in two detection modes: (i) as a kinetic inductance detector (KID) or (ii) as a single-photon detector (SPD). Two superconducting nanowires developed for use as single-photon detectors (SNSPDs) are embedded as the inductive (L) component in resonant inductor/capacitor (LC) circuits coupled to a microwave transmission line. The capacitors are low loss commercial chip capacitors and limit the internal quality factor of the resonators to approximately Q i = 170. The resonator quality factor, Q r ≃ 23 , is dominated by the coupling to the feedline and limits the detection bandwidth to on the order of 1 MHz. When operated in KID mode, the detectors are AC biased with tones at their resonant frequencies of 45.85 and 91.81 MHz. In the low-bias, standard KID mode, a single photon produces a hot spot that does not turn an entire section of the line normal but only increases the kinetic inductance. In the high-bias, critical KID mode, a photon event turns a section of the line normal and the resonance is destroyed until the normal region is dissipated. When operated as an SPD in Geiger mode, the resonators are DC biased through cryogenic bias tees and each photon produces a sharp voltage step followed by a ringdown signal at the resonant frequency of the detector which is converted to a standard pulse with an envelope detector. We show that AC biasing in the critical KID mode is inferior to the sensitivity achieved in DC-biased SPD mode due to the small fraction of time spent near the critical current with an AC bias.

Original languageEnglish (US)
Pages (from-to)386-393
Number of pages8
JournalJournal of Low Temperature Physics
Issue number5-6
StatePublished - Mar 15 2019


  • Cryogenic
  • Detector
  • KID
  • Nanowire
  • Resonator
  • SPD
  • Superconducting

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


Dive into the research topics of 'Operation of a Superconducting Nanowire in Two Detection Modes: KID and SPD'. Together they form a unique fingerprint.

Cite this