Workpackage leader: Dr Mikko Möttönen, Aalto University

Electromagnetic metrology for microwave frequencies at the level of single microwave photons is still in its infancy despite its great technological importance. Detection of single microwave photons in real-time would enable, for example, quantum computing with microwave photons, precision length metrology that would go beyond the standard quantum limit when measuring small phase shifts and displacements, and ultrasensitive spectrum analysis of cryogenic environments. However, unlike at optical frequencies, there are no detectors that can reliably resolve single microwave photon events.

This REG aims to go beyond the current state-of-the-art in both detector and emitter technologies at the level of single microwave photons. Specific tasks include (1) development of a novel type of microwave photon detector based on a superconductor-normal-metal-superconductor (SNS) device for the frequency range 10 GHz - 80 GHz; (2) characterization of incoherent microwave photon sources, and (3) integration of a SNS single-photon detector on-chip with a single-photon source. The methods developed in this REG for detecting, creating and eliminating microwave radiation at very small signal levels will enable breakthroughs in a wide range of applications where high-fidelity nanoscale quantum circuits are required.