Nonlocal supercurrent of quartets in a three-terminal Josephson junction

Abstract

A novel nonlocal supercurrent, carried by quartets, each consisting of four electrons, is expected to appear in a voltage-biased three-terminal Josephson junction. This supercurrent results from a nonlocal Andreev bound state (ABS), formed among three superconducting terminals. While in a two-terminal Josephson junction the usual ABS, and thus the dc Josephson current, exists only in equilibrium, the ABS, which gives rise to the quartet supercurrent, persists in the nonlinear regime. In this work, we report such resonance in a highly coherent three-terminal Josephson junction made in an InAs nanowire in proximity to an aluminum superconductor. In addition to nonlocal conductance measurements, cross-correlation measurements of current fluctuations provided a distinctive signature of the quartet supercurrent. Multiple device geometries had been tested, allowing us to rule out competing mechanisms and to establish the underlying microscopic origin of this coherent nondissipative current.

Topological transconductance quantization in a four-terminal Josephson junction

“…At lower voltages, 0.1 /e V 2 /e, we observe a complex dependence of the direct conductances as well as the transconductances, with resonant features that are related with multiple Andreev reflections involving various leads [28][29][30][31][32][33].…”

Transport studies in a gate-tunable three-terminal Josephson junction

“…By increasing the number of terminals, one can access a higher dimensional phase space spanned by the relative phases or voltages between the several terminals. This can lead to new effects, such as interactions between supercurrents [22,23], coexistence of dissipative currents and supercurrents [24], multi-loop superconducting interferometry [25], or generalizations of * vpribiag@umn.edu all pair-wise currents flow through a small number of modes. The topological phase transitions in the Andreev levels manifest quantized conductances and transconductances which change as a function of the terminal phases and/or voltages.…”

Tunable pseudogaps due to nonlocal coherent transport in voltage-biased three-terminal Josephson junctions

“…Two of the first experiments study a diffusive TTJ, where robust transport anomalies [9] and Shapiro steps [10] were observed as a function of two applied voltages V 1,3 , that have been interpreted in terms of three quartet modes. The third experiment studies a phase-coherent TTJ realized in a semiconducting nanowire [11], showing positive current cross-correlation that are interpreted as evidence of the nonlocal quartet processes.…”

“…Recently, the study of junctions between N 3 superconductors has attracted considerable interest, both theoretical [5][6][7][8] and experimental [9][10][11][12]. Unique features have been revealed, that do not manifest in the N = 2 junctions.…”

“…The situation has been recently investigated in Refs. [9][10][11]. Two of the first experiments study a diffusive TTJ, where robust transport anomalies [9] and Shapiro steps [10] were observed as a function of two applied voltages V 1,3 , that have been interpreted in terms of three quartet modes.…”