Microwave Quantum Photonics for Quantum Technology and Fundamental Physics

ongoing

With the proposed research programme we plan to pioneer a platform that provides experimental access to the statistics of the microwave photons, thus opening up single-photon experiments in solid-state quantum devices. Microwave photons play a major role throughout all solid-state quantum technology architectures, including superconducting qubits as well as charge and spin qubits in semiconductors, where they are used for control, coupling and readout. However, the particle nature of the photons and in particular their statistical properties remain unexplored. The main roadblock here is the lack of suitable microwave photodetectors for performing continuous photon counting at high quantum conversion efficiency. We will create sensors probing the timing between two photons with time resolution better than the time–uncertainty Heisenberg limit of the individual photons. Thereby we will create novel measurement tools applicable throughout the quantum technology field. In particular, the photon counting developed in this research programme will open up the avenue to implement quantum computing based on so-called boson sampling with superconducting circuits, combining two key requirements for practical quantum computing: the programmability of the superconducting circuits and the stronger quantum advantage of quantum processors based on boson sampling. Beyond enabling these new measurement capabilities, on the fundamental side we generate unique experimental insights. The interplay between correlated bosonic and fermionic states — e.g., on how the bosonic particle statistics of the photons map onto the fermionic ones of the electrons — is likely to spur new experimental activities around many-body physics. Furthermore, the detection timing resolution beyond the Heisenberg limit will also shed light on the still unknown physics question on how measurements really work and act in the quantum physics domain.