Coherent Charge Transport in Ballistic InSb Nanowire Josephson Junctions

Abstract

Hybrid InSb nanowire-superconductor devices are promising for investigating Majorana modes and topological quantum computation in solid-state devices. An experimental realisation of ballistic, phase-coherent superconductor-nanowire hybrid devices is a necessary step towards engineering topological superconducting electronics. Here, we report on a low-temperature transport study of Josephson junction devices fabricated from InSb nanowires grown by molecular-beam epitaxy and provide a clear evidence for phase-coherent, ballistic charge transport through the nanowires in the junctions. We demonstrate that our devices show gate-tunable proximity-induced supercurrent and clear signatures of multiple Andreev reflections in the differential conductance, indicating phase-coherent transport within the junctions. We also observe periodic modulations of the critical current that can be associated with the Fabry-Pérot interference in the nanowires in the ballistic transport regime. Our work shows that the InSb nanowires grown by molecular-beam epitaxy are of excellent material quality and hybrid superconducting devices made from these nanowires are highly desirable for investigation of the novel physics in topological states of matter and for applications in topological quantum electronics.

0−π phase transition in hybrid superconductor–InSb nanowire quantum dot devices

“…1(g). A typical I -V shape of an overdamped Josephson junction comprising a supercurrent branch and a dissipative branch can be recognized, with a switching current I SW ∼ 1 nA which is consistent with typical magnitude in similar nanowire Josephson junctions [50]. Hence, the zero-bias conductance peak can be attributed to the manifestation of a supercurrent and this is also confirmed by data from a second similar device [see Fig.…”

“…We argue that these broad resonances are the manifestation of the Fabry-Pérot interference in a ballistic nanowire. Fabry-Pérot interference patterns have been observed in InSb nanowire Josephson junctions in our previous work [50] and a mean free path l e ∼ 80 nm of our InSb nanowires has been extracted. Given here the channel length L 65 nm < l e , the NWQD device is supposed to work in the ballistic regime and the occurrence of the Fabry-Pérot interference in the open regime is quite reasonable.…”

Supercurrent and Multiple Andreev Reflections in InSb Nanosheet SNS Junctions

“…So the measured values of I c R n product are much smaller than expected upon. Such strong suppression of the I c R n product has been commonly observed in a mesoscopic Josephson junction and may be accounted for the difference between the switching current and the intrinsic critical current …”

“…In a SNS junction, multiple Andreev reflections happens when the quasiparticles traverse the normal region and perform Andreev reflection at the interface keeping phase coherent. This give rise to subharmonic energy‐gap structures which is often observed as a serious of differential conductance peaks at finite bias voltages symmetrically around in experiments …”

Synthesis of Amorphous InSb Nanowires and a Study of the Effects of Laser Radiation and Thermal Annealing on Nanowire Crystallinity

“…Of the semiconducting NWs, the III-V group of semiconductors are promising and of these indium antimonide ( ) is particularly interesting because it has the smallest direct energy band gap (0.17 eV at room temperature) [ 2 ], and very high electron mobility (77,000 cm V s ) [ 3 ]; making it an ideal material for use as field effective transistors and long-wavelength detectors [ 4 , 5 ]. Crystalline ( c - ) NWs have been synthesized by various techniques such as pulsed electrodeposition technique [ 2 ], pulsed-laser chemical vapor deposition [ 6 ], molecular beam epitaxy [ 7 , 8 ], metal organic vapor phase epitaxy [ 9 ], and chemical vapor deposition [ 10 , 11 ]. In most cases, growth of c - NWs follows the metal-catalyst assisted vapor-liquid-solid (VLS) growth mechanism [ 1 ], and NW growth continues as long as and vapors are supplied to the molten alloy droplet.…”