SUPERCONDUCTING QUANTUM DETECTORS IN YBCO

The discovery of high-temperature superconductors has led to great eff orts to find potential applications, including the development of phot on detectors. We review the limitations of the different approaches pr oposed for realizing superconducting photon detectors. The structure a nd operation of a new quantum superconducting kinetic inductance detec tor (QSKID) with a SQUID readout circuit is described. The QSKID is ma de from a superconducting loop where the photosignals are generated in response to photoinduced changes in the condensate's kinetic inductan ce. The QSKID operates in the zero-resistance superconducting state, t hereby circumventing Johnson noise.