Nov 26, 2009
Collaboration fabricates superconducting devices with high precision
Scientists from the University of Melbourne, La Trobe University and Leeds University have joined forces to fabricate advanced superconducting devices using focus ion beam (FIB) technology. The technique, which allows record-low structure sizes of only few tens of nanometres, has been applied to produce good-quality Josephson junctions, superconducting nanowires and some of the most magnetic field-sensitive DC-SQUIDs ever made, having a record low loop diameter of only 50 nm.
More importantly, by using superconducting nanowires fabricated using this technique it has been possible to observe thermally assisted slippage of the superconducting phase (TAPS) and quantum slippage of the phase (QPS). This result is of great importance, as the latter of these phenomena has so far only been observed in very few systems and is still a very controversial topic.
QPS could be applied to the fabrication of devices useful for defining a new standard for current as, contrary to normal Josephson junctions, if subjected to microwave irradiation, the arrangement is expected to show a quantized plateau in the device current. The QPS effect is also under investigation as a replacement of the Josephson effect in a new generation of superconducting flux qbits that are expected to have lower sources of decoherence. The fabrication of phase-slip devices using fabrication techniques that are compatible with conventional device engineering is a significant step towards these goals.
About the author
The study was performed in close collaboration between the University of Melbourne, La Trobe University and the University of Leeds and supported by the Australian Research Council and the EPSRC. Dr Giuseppe Carlo Tettamanzi is a FOM postdoctoral fellow at the Kavli Institute for NanoScience of the Technical University of Delft working under the direction of Prof. S Rogge and Prof. H W M Salemink and was a PhD student at the University of Melbourne between 2004 and 2007 as this work has been carried on as part of his PhD thesis. Dr Chris Pakes is a lecturer at the La Trobe University, Melbourne, Australia. Dr Alessandro Potenza was a PhD student at the University of Leeds and is now working at the British Patent Office. S Rubanov is a research fellow at the Bio21 Institute of the University of Melbourne, Dr Christopher Marrows is a reader in Condensed Matter Physics at the University of Leeds. Prof. Steven Prawer is a professor of physics at the School of Physics of the University of Melbourne and the inaugural director of the Melbourne Material Institute, an interdepartmental centre within the University of Melbourne for innovative, high-risk high-return materials research programs.