Ultra low noise YBa2Cu3O7-delta nano superconducting quantum interference devices implementing nanowires

We present results on ultra low noise YBa2Cu3O7-delta (YBCO) nano Superconducting QUantum Interference Devices (nanoSQUIDs). To realize such devices, we implemented high quality YBCO nanowires, working as weak links between two electrodes. We observe critical current modulation as a function of an externally applied magnetic field in the full temperature range below the transition temperature T-C. The white flux noise below 1 mu Phi(0)/root Hz at T = 8K makes our nanoSQUIDs very attractive for the detection of small spin systems