Probing nonlocality of Majorana fermions in Josephson junctions of Kitaev chains connected to normal metal leads

Abstract

Kitaev chain (KC) is a prototypical model for the study of Majorana fermions (MFs). In the topological phase, a KC hosts two MFs at its ends. Being separated in space, these two MFs are nonlocal. The nonlocal transport in a KC biased between two normal metal leads is mediated by electron tunneling (ET) and crossed Andreev reflection (CAR). ET contributes positively while CAR contributes negatively to the nonlocal conductance. Enhanced CAR and hence a negative nonlocal conductance is a hallmark of nonlocality of MFs. But simple conductance measurements in the above setup cannot probe the nonlocality of MFs due to the almost cancellation of currents from ET and CAR. On the other hand, a Josephson junction between two KCs hosts two Andreev bound states (ABSs) at the junction formed by a recombination of Majorana fermions of the individual KCs. The energies of the ABSs are away from zero and can be changed by altering the superconducting phase difference. A Josephson junction between two finitely long KCs hosts two MFs at the two ends and two ABSs at the junction. We show that when normal metal leads are connected to two ends of such a Josephson junction, the nonlocal conductance of the setup can be negative for bias values equal to the energies of the ABSs. Thus the nonlocal conductance in such setup can probe the nonlocality of the constituent MFs.

6 pages, 6 captioned figures, version accepted in Solid State Communications

References in corpus (12)

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• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
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• Supercurrent blockade in Josephson junctions with a Majorana wire
• Long-range Cooper pair splitter with high entanglement production rate
• Enhancement of crossed Andreev reflection in a Kitaev ladder connected to normal metal leads
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Cited by in corpus (5)

• Tunable crossed Andreev reflection in a heterostructure consisting of ferromagnets, normal metal and superconductors
• Enhanced $2\pi$-periodic Aharonov-Bohm Effect as a Signature of Majorana Zero Modes Probed by Nonlocal Measurements
• Majorana fermions in Kitaev chains side-coupled to normal metals
• Multi-locational Majorana Zero Modes
• Tunable effective length of fractional Josephson junctions