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

L Leif Bauer (Elmore Family School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907,) D Daien He (The Elmore Family School of Electrical and Computer Engineering, Purdue University 1 , West Lafayette, Indiana 47907,) S Sathwik Bharadwaj (The Elmore Family School of Electrical and Computer Engineering, Purdue University 1 , West Lafayette, Indiana 47907,) S Shunshun Liu P Prasanna V. Balachandran Z Zubin Jacob (Elmore Family School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907,)

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 different class of type-1.5 superconducting nanowire single photon detectors (SNSPDs) based on two bandgap superconductors with high transition temperatures such as MgB2 (Tc∼ 38.6 K). 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.

Article Details

Volume / Issue Vol. 127, Issue 12
Published September 22, 2025
ISSN 0003-6951
Publisher American Institute of Physics

Journal Info

Applied Physics Letters

American Institute of Physics

ISSN: 0003-6951 Physical Sciences

Authors (6)

L

Leif Bauer

Elmore Family School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907,

D

Daien He

The Elmore Family School of Electrical and Computer Engineering, Purdue University 1 , West Lafayette, Indiana 47907,

S

Sathwik Bharadwaj

The Elmore Family School of Electrical and Computer Engineering, Purdue University 1 , West Lafayette, Indiana 47907,

S

Shunshun Liu

P

Prasanna V. Balachandran

Z

Zubin Jacob

Elmore Family School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907,