Single-Shot Quantum Non-Demolition Detection of Individual Itinerant Microwave Photons

Messages are often transmitted with light, the quantum unit of it being the photon. In the microwave regime used in our superconducting circuits, detecting a single itinerant photon is however challenging, as it possesses up to 5 orders of magnitude less energy than its optical counterpart. In this work, we show how to transfer the information of the flying photon’s passage into an excitation of a stationary artificial atom, a qubit. By reading out the state of the latter, we acquire knowledge about the photon’s presence without destroying it. This ‘non-demolition’ aspect opens up new possibilities of placing the detector in the middle of the photon’s path, and letting it propagate towards another destination.

Article: J. - C. Besse, S. Gasparinetti, M. C. Collodo, T. Walter, P. Kurpiers, M. Pechal, C. Eichler, and A. Wallraff, Phys. Rev. X 8, 021003 (2018)

Paper on Single-Shot Quantum Nondemolition Detection in PRX