Non-Reciprocal Supercurrents in a Field-Free Graphene Josephson Triode

Abstract

Superconducting diodes are proposed non-reciprocal circuit elements that should exhibit nondissipative transport in one direction while being resistive in the opposite direction. Multiple examples of such devices have emerged in the past couple of years, however their efficiency is typically limited, and most of them require magnetic field to function. Here we present a device achieving efficiencies upwards of 90% while operating at zero field. Our samples consist of a network of three graphene Josephson junctions linked by a common superconducting island, to which we refer as a Josephson triode. The triode is tuned by applying a control current to one of the contacts, thereby breaking the time-reversal symmetry of the current flow. The triode's utility is demonstrated by rectifying a small (tens of nA amplitude) applied square wave. We speculate that devices of this type could be realistically employed in the modern quantum circuits.

Reconfigurable magnetic-field-free superconducting diode effect in multi-terminal Josephson junctions

“…3D, the voltage obtained from the pulsed measurement occasionally fluctuates between zero and non-zero values at T = 12 mK. This is due to the hysteresis in switching currents (I c and I r ) caused by the Joule heating effect (28). We find that the fluctuations disappear at higher temperatures, and we obtain a diode efficiency of ∼ 100% at T = 220 mK (see fig.…”

“…Therefore, careful engineering of the interplay between spin-orbit interactions, topological phases, and magnetic fields can lead to the observation of the SDE. To this point, the SDE has been experimentally reported in a multitude of systems including but not limited to: non-centrosymmetric superconductors with the magneto-chiral anisotropy (17,18,19,20,21), Josephson junctions (JJs) based on Dirac semimetals with finite-momentum Cooper pairing (22), two-dimensional (2D) van der Waals heterostructures (23,21,24,25,26), three-terminal JJs based on InAs in the presence of a magnetic field (27), and a network of graphene JJs (28).…”

Superconducting diode effect in quasi-one-dimensional systems

“…Following the initial observations, extensive work has been done to show the signature of SDE in different bulk materials [4][5][6][7][8]. This diode effect was also observed and thoroughly studied in Josephson junctions [9][10][11][12][13][14][15][16] (first in the context of the anomalous Josephson effect [17][18][19][20][21]) and even in the absence of an applied magnetic field [22][23][24][25][26].…”

Diamagnetic mechanism of critical current non-reciprocity in multilayered superconductors

“…The term "superconducting diode effect" has been used to describe NRC in different systems, including thin superconducting films [13][14][15][16][17][18] and Josephson junctions [19][20][21][22][23][24][25][26][27] . In the former experiments the presence of outof-plane magnetic field and formation of vortices is essential for the observation of NRC, in this case the critical current is determined by the strength and symmetry of the flux pinning potential.…”