TY - JOUR

T1 - Photon-Assisted Tunneling of High-Order Multiple Andreev Reflections in Epitaxial Nanowire Josephson Junctions

AU - Carrad, Damon James

AU - Stampfer, Lukas

AU - Olsteins, Dags

AU - Petersen, Christian Emmanuel Noes

AU - Khan, Sabbir A. .

AU - Krogstrup, Peter

AU - Jespersen, Thomas Sand

PY - 2022/7/21

Y1 - 2022/7/21

N2 - Semiconductor/superconductor hybrids exhibit a range of phenomena that can be exploited for the study of novel physics and the development of new technologies. Understanding the origin of the energy spectrum of such hybrids is therefore a crucial goal. Here, we study Josephson junctions defined by shadow epitaxy on InAsSb/Al nanowires. The devices exhibit gate-tunable supercurrents at low temperatures and multiple Andreev reflections (MARs) at finite voltage bias. Under microwave irradiation, photon-assisted tunneling (PAT) of MARs produces characteristic oscillating sidebands at quantized energies, which depend on MAR order, n, in agreement with a recently suggested modification of the classical Tien-Gordon equation. The scaling of the quantized energy spacings with microwave frequency provides independent confirmation of the effective charge, ne, transferred by the nth-order tunneling process. The measurements suggest PAT as a powerful method for assigning the origin of low-energy spectral features in hybrid Josephson devices.

AB - Semiconductor/superconductor hybrids exhibit a range of phenomena that can be exploited for the study of novel physics and the development of new technologies. Understanding the origin of the energy spectrum of such hybrids is therefore a crucial goal. Here, we study Josephson junctions defined by shadow epitaxy on InAsSb/Al nanowires. The devices exhibit gate-tunable supercurrents at low temperatures and multiple Andreev reflections (MARs) at finite voltage bias. Under microwave irradiation, photon-assisted tunneling (PAT) of MARs produces characteristic oscillating sidebands at quantized energies, which depend on MAR order, n, in agreement with a recently suggested modification of the classical Tien-Gordon equation. The scaling of the quantized energy spacings with microwave frequency provides independent confirmation of the effective charge, ne, transferred by the nth-order tunneling process. The measurements suggest PAT as a powerful method for assigning the origin of low-energy spectral features in hybrid Josephson devices.

KW - semiconductor/superconductor hybrids

KW - nanowires

KW - multiple Andreev reflections

KW - photon-assisted tunneling

KW - Tien-Gordon

KW - ENERGY-GAP STRUCTURE

KW - SHOT-NOISE

KW - CHARGE

KW - SUPERCURRENT

KW - GROWTH

KW - STATE

U2 - 10.1021/acs.nanolett.2c01840

DO - 10.1021/acs.nanolett.2c01840

M3 - Journal article

C2 - 35862144

VL - 22

SP - 6262

EP - 6267

JO - Nano Letters

JF - Nano Letters

SN - 1530-6984

IS - 15

ER -