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arXiv · 2507.01240

Type-1.5 SNSPD: Interacting vortex theory of two bandgap superconducting single photon detectors

Leif Bauer·Daien He·Sathwik Bharadwaj·Shunshun Liu·Prasanna V. Balachandran·Zubin Jacob
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Abstract

Photon detectors based on type-2 superconductors have found widespread applications from on-chip quantum computing to quantum remote sensing. Here, we develop the theory for a new class of type-1.5 superconducting nanowire single photon detectors (SNSPDs) based on two bandgap superconductors with high transition temperatures such as MgB2 (Tc ~38.6K). We show that vortex-vortex interactions in two component condensates lead to a unique operating regime where single photons can seed multiple vortices within a hotspot. We also show that dark counts are suppressed in the type-1.5 regime compared to the widely studied type-2 SNSPDs. Our work opens the door for exploring the unique vortex physics of two-gap superconductors for quantum device applications.

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Leif Bauer, Daien He, Sathwik Bharadwaj, Shunshun Liu, Prasanna V. Balachandran, Zubin Jacob. 2025-07-01. Type-1.5 SNSPD: Interacting vortex theory of two bandgap superconducting single photon detectors. https://arxiv.org/abs/2507.01240

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