Spin-filtered measurements of Andreev bound states

Abstract

A semiconductor nanowire brought in proximity to a superconductor can form discrete, particle-hole symmetric states, known as Andreev bound states (ABSs). An ABS can be found in its ground or excited states of different spin and parity, such as a spin-zero singlet state with an even number of electrons or a spin-1/2 doublet state with an odd number of electrons. Considering the difference between spin of the even and odd states, spin-filtered measurements have the potential to reveal the underlying ground state. To directly measure the spin of single-electron excitations, we probe an ABS using a spin-polarized quantum dot that acts as a bipolar spin filter, in combination with a non-polarized tunnel junction in a three-terminal circuit. We observe a spin-polarized excitation spectrum of the ABS, which in some cases is fully spin-polarized, despite the presence of strong spin-orbit interaction in the InSb nanowires. In addition, decoupling the hybrid from the normal lead blocks the ABS relaxation resulting in a current blockade where the ABS is trapped in an excited state. Spin-polarized spectroscopy of hybrid nanowire devices, as demonstrated here, is proposed as an experimental tool to support the observation of topological superconductivity.

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Cited by in corpus (7)

• Crossed Andreev reflection and elastic co-tunneling in a three-site Kitaev chain nanowire device
• Charge sensing the parity of an Andreev molecule
• Supercurrent from the imaginary part of the Andreev levels in non-Hermitian Josephson junctions
• Spin-resolved nonlocal transport in proximitized Rashba nanowires
• Revisiting the Poor Man's Majoranas: The Spin-Exchange Induced Spillover Effect
• Determination of the current-phase relation of an InAs 2DEG Josephson junction with a microwave resonator
• Transient triplet blockade in Andreev junction