Waveguide-integrated superconducting nanowire single-photon detectors (SNSPD’s)​ operating in strong magnetic fields

Efficient detection of single-photon emission is a vital aspect in the design of quantum computers based on color centers in diamond. SNSPD’s are the best candidate for this purpose, showing high detection efficiencies in combination with a low dark-count rate. ​

Typically, SNSPD’s and qubits are separated from each other, connected by optical fibers. The goal, however, is to integrate all subsystems of the quantum computer on a single chip, which includes the SNSPD’s. On-chip fiber connections are, of course, not practical, so waveguide structures are used instead. SNSPD’s are placed on top of these structures. As the light travels through the waveguides, the photons are absorbed by the nanowire, resulting in a detection event. ​

A challenge that arises with integration of the quantum computer subsystems is the change in operation environment for individual components. Color center qubits require biasing with a high static magnetic field. On-chip integration of both qubit and detector requires the SNSPD’s to operate in this magnetic field as well. This requires optimization, since magnetic fields alter the properties of superconducting nanowires. ​

Project: Investigation of superconductor material suitability for operation in high magnetic fields
In this project, you will do the following:
– Fabrication of waveguide-coupled SNSPD’s in a cleanroom
– Testing of the SNSPD performance in strong magnetic fields.

Interested? Please contact Ryoichi Ishihara r.ishihara@tudelft.nl or Maurice van der Maas <M.C.vanderMaas@tudelft.nl>