Transport and noise properties of YBCO nanowire based nanoSQUIDs

Abstract

The development of quantum limited magnetic flux sensors has recently gained a lot of attention for the possibility of detecting the magnetic moment of nanoscaled systems. Here, the ultimate goal is the observation of a single spin. Such sensors are of fundamental importance for applications, ranging from spintronics and spin-based quantum information processing, to fundamental studies of nano-magnetism in molecules and magnetic nanoclusters. A nano-scale superconducting quantum interference device (nanoSQUID) is indeed a promising candidate to reach this ambitious goal. Nanowires, fabricated of high critical temperature superconductors (HTS), have been shown to be a valid candidate for the realization of nanoSQUIDs. A crucial requirement to achieve the necessary flux sensitivity and spatial resolution, is a SQUID loop on the nanometer scale. Moreover, HTS nanowire-based SQUIDs in combination with large area pickup loops or flux transformers might become instrumental in magnetometer applications, such as magneto encephalography and low field magnetic resonance imaging, where low intrinsic magnetic field noise is required. In this review we will give a survey on the state of the art of YBa2Cu3O7−δ thin film nanowires and their implementation in low noise nanoSQUIDs and magnetometers.

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

“…The limit of detectivity of the dc SQUID can be of the order of 1 fT/√Hz [45][46][47] in a frequency range of magnetic field from dc to GHz [48]. The maximum possible detection limit is achieved for millimeter-sized sensors [49], but further miniaturization of SQUID magnetometers to a micro-or nano-meter size is followed by a reduction in sensitivity [50,51]. The schematic image of a common sensing element of the dc SQUID magnetometer is presented in Figure 3.…”

“…The latest work showing the optimization of SQUID magnetometer parameters such as critical current, voltage swing and magnetic noise reports a reduction of the noise level by a factor of 5 (A. Vettoliere et al [186]). The miniaturization of SQUIDs (including utilization of nanofabrication processes) in a yttrium barium copper oxide (YBCO) nanowires-based system was recently made by Trabaldo et al [50]. The research reports the detection of 'white flux' noise and has the potential to be further miniaturized, but this process is technically challenging.…”

Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics

“…Consequently, resonator stability can be essential for qubit circuit stability. Moreover, thermally activated vortex motion can contribute to 1/ f noise and critical current fluctuations 27,28 in quantum circuits and is a suspected source of the dark count rate in superconducting nanowire single-photon detectors 29,30 .…”

Thermopower and thermophase in a $d$-wave superconductor

“…From a fundamental point of view this type of thermoelectric response can be used to probe the influence of impurities in unconventional superconductors. But it has further implications for applications of unconventional superconducting devices, as for instance based on the high-T c cuprates [39].…”