Multiterminal Ballistic Josephson Effect in Monocrystalline Gold

Abstract

We report on the realization of a planar, quasi-ballistic Josephson junction array using a Au micron-sized single-crystal. The system exhibits a nonlocal, multiterminal Josephson effect, where the supercurrent between any two superconducting leads is governed by the phase coherence across the entire crystal. Key evidence includes a non-monotonic dependence of the critical current on junction length and magnetic interference patterns with periods corresponding to the shared normal-metal area. Nonlocal transport measurements further confirm that the supercurrent between two electrodes depends on the phase configuration of all the others. Our results, supported by a developed theoretical model, establish a platform for exploring complex superconducting phenomena in multiterminal ballistic systems.

Figures (3)

• Figure 1: (a) False-colored SEM image of the Josephson junction array with Al electrodes (labeled $A_1$--$A_4$, $B_1$--$B_4$) on a Au crystal. Inset: measurement configuration schematic. (b) Critical current $I_c^{A_i-B_i}$ versus temperature: experimental data (dots) and theoretical fits (lines) with interface transmission $D = 0.03$. (c) Model for Josephson current calculation in a single junction.
• Figure 2: Differential resistance $dV/dI$ at the $A_2$--$A_3$ junction with simultaneous currents $I^{A_2-A_3}$ and $I^{A_1-A_4}$. $T=0.7K$.
• Figure 3: (a)-(d) Experimental data for $I_c^{A_i-B_i}$ (dark blue region boundaries) versus perpendicular magnetic field. (a')-(d') Theoretical results for $I_c^{A_i-B_i}$ versus perpendicular magnetic field. $T=0.7K$.