Microwave-induced conductance replicas in hybrid Josephson junctions without Floquet-Andreev states

Abstract

Light-matter interaction enables engineering of non-equilibrium quantum systems. In condensed matter, spatially and temporally cyclic Hamiltonians are expected to generate energy-periodic Floquet states, with properties inaccessible at thermal equilibrium. A recent work explored the tunnelling conductance of a planar Josephson junction under microwave irradiation, and interpreted replicas of conductance features as evidence of steady Floquet-Andreev states. Here we realise a similar device in a hybrid superconducting-semiconducting heterostructure, which utilises a tunnelling probe with gate-tunable transparency and allows simultaneous measurements of Andreev spectrum and current-phase relation of the planar Josephson junction. We show that, in our devices, spectral replicas in sub-gap conductance emerging under microwave irradiation are caused by photon assisted tunnelling of electrons into Andreev states. The current-phase relation under microwave irradiation is also explained by the interaction of Andreev states with microwave photons, without the need to invoke Floquet states. The techniques outlined in this study establish a baseline to distinguish photon assisted tunnelling from Floquet-Andreev states in mesoscopic devices, a crucial development towards understanding light-matter coupling in hybrid nanostructures.

References in corpus (12)

• Photovoltaic Hall effect in graphene
• Coherent manipulation of an Andreev spin qubit
• Transparent Semiconductor-Superconductor Interface and Induced Gap in an Epitaxial Heterostructure Josephson Junction
• Steady Floquet-Andreev States Probed by Tunnelling Spectroscopy
• Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
• Superconducting atomic contacts under microwave irradiation
• Floquet Majorana zero and $\pi$ modes in planar Josephson junctions
• Theory of Microwave-Assisted Supercurrent in Diffusive SNS Junctions
• Floquet engineering a bosonic Josephson junction
• Floquet Majorana bound states in voltage-biased Planar Josephson Junctions
• Phase-dependent dissipation and supercurrent of a graphene-superconductor ring under microwave irradiation
• Photon assisted tunneling of high order multiple Andreev reflections in epitaxial nanowire Josephson junctions

Cited by in corpus (3)

• Light-induced Floquet spin-triplet Cooper pairs in unconventional magnets
• Nonequilibrium Andreev resonances in ballistic graphene Andreev interferometers
• Nonequilibrium hysteretic phase transitions in periodically light-driven superconductors