Andreev-level spectroscopy and Josephson-current switching in a three-terminal Josephson junction

Abstract

We calculate the electrical currents through a superconductor -insulator -superconductor junction which is also weakly coupled to a normal metal side probe. The voltage V applied to the normal metal terminal controls the occupation of Andreev energy levels En, and therefore controls the Josephson current flowing through these levels. Whenever the probe voltage crosses an Andreev level, the Josephson current changes abruptly by an amount equal to the current flowing through the Andreev level. The differential conductance along the normal metal terminal permits spectroscopy of the Andreev levels. In a short junction (L ≪ ξ0), the critical current switches abruptly from the Ambegaokar-Baratoff value to zero when the probe voltage is approximately equal to the superconducting energy gap (|eV | ≃ ∆). The magnitude of the Josephson current switching in a long junction (L ≫ ξ0) , and the range of probe voltages over which the Josephson current differs from its equilibrium value, are much smaller than for three-terminal ballistic superconductor -normal metal -superconductor junctions.

The current-phase relation in Josephson junctions

“…In this review we shall restrict ourselves to the stationary Josephson effect in two-terminal weak links when nonequilibrium effects do not play a role. This corresponds to the above-mentioned case (a), when the C⌽R is determined by the spectral current Im͕I E ()͖, depend-2 See, for example, Zaitsev, 1976Zaitsev, , 1993Zaitsev, , 1995Artemenko et al, 1979;Aslamazov and Lempitskii, 1982;Lempitskii, 1983;Zaikin 1983Zaikin , 1988Aslamazov and Volkov, 1986;van Wees et al, 1991;Shumeiko et al, 1993;Gorelik et al, 1995;Volkov, 1995;Chang and Bagwell, 1997;Samuelsson et al, 1997Samuelsson et al, , 2000Samuelsson et al, , 2001Volkov and Takayanagi, 1997;Morpurgo et al, 1998;Tolga Ilhan et al, 1998;Wilhelm et al, 1998Wilhelm et al, , 2000Yip, 1998;Baselmans et al, 1999Baselmans et al, , 2001Kutchinsky et al, 1999Kutchinsky et al, , 2000Neurohr et al, 1999;Heikkilä et al, 2000Heikkilä et al, , 2002Seviour and Volkov, 2000;Sun et al, 2000;Baselmans, Heikkila, et al 2002;Huang et al, 2002;Zhu et al, 2002;Brinkman et al, 2003. FIG. 1.…”

Andreev bound states and the π-junction transition in a superconductor/quantum-dot/superconductor system

“…Unfortunately, the π-junction transition cannot be directly detected in the two-terminal tunnel junction because the current source is used in the measurement to control the supercurrent rather than the phase difference. However, in a mesoscopic superconductor/normal-metal/superconductor (SNS) junction with the N-region coupled to normal electrode(s) [4,5], the phase difference can be determined independently from the coherent Andreev reflection current which is proportional to…”

Current noise in three-terminal hybrid quantum point contacts

“…By tuning the voltage at the N lead, the magnitude and sign of the Josephson current between two superconducting leads can be well controlled [7][8][9][10][11]. The N lead can also be a powerful probe to reveal the spectroscopic information of the central region [12]. A recent experiment [13] has demonstrated the first spectroscopy of the evolution of Andreev bound states in a carbon nanotube based three-terminal hybrid device.…”