Quantum Physics in One Dimension using Nanostructured Josephson-junction Arrays

Synopsis

Quantum physics-archive in one spatial dimension is peculiar and remarkably rich, yet even with strong interactions and disorder, surprisingly tractable. This is due to the fact that the lowenergy physics-archive of nearly all 1D systems can be cast in terms of the Luttinger liquid, a key concept that parallels that of the Fermi liquid in higher dimensions. Although there have been many theoretical proposals to use linear chains and ladders of Josephson junctions to create novel quantum phases and innovative electronic devices, such as quantum systems with topologically protected states, only modest progress has been made experimentally. One major roadblock has been understanding the role of disorder in such systems.

I will present recent experiments from our lab that shed light on the competition between the Mott insulator and Bose glass phase. The Bose glass is thought to describe helium-4 in porous media, cold atoms in disordered optical potentials, disordered magnetic insulators, and thin superconducting films. The ubiquity of such a glass phase in Josephson-junction chains has important implications for their proposed use as a fundamental current standard, which is based on synchronisation of coherent tunnelling of flux quanta (quantum phase slips). We have also recently extended our measurements to SQUID chains and ladders, finding quite unexpected and tantalising behaviour.

Bio

Timothy Duty is a experimental condensed matter physicist who leads the superconducting device laboratory at the University of New South Wales. He received his undergraduate degree from Virginia Tech, followed by Masters and Doctoral degrees from the University of British Columbia. As one of D-wave’s very first employees, he became keenly interested in the quantum physics-archive of superconducting circuits following his PhD. During his postdoctoral research at Chalmers in Sweden, he pioneered development of one of the earliest working superconducting charge qubits, and novel methods for control and sensing of single charge transport. At UNSW his focus has centred on quantum phenomena in complex nano-scale superconducting circuits, focusing on experiments that elucidate the physics-archive of strongly-correlated, many-body charge transport using a novel platform based on Josephson-junction arrays.