Zero-Bias Anomaly in a Nanowire Quantum Dot Coupled to Superconductors

Lee, Eduardo J. H.; Jiang, Xiaocheng; Aguado, Ramón; Katsaros, Georgios; Lieber, Charles M.; Franceschi, S. De

doi:10.1103/physrevlett.109.186802

Cited by 362 publications

(339 citation statements)

References 29 publications

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“…It has been pointed out that several effects such as disorder induced Andreev bounded states, 18 Kondo effect, 15,33 weak antilocalization, 20 and reflectionless tunneling 34,35 may cause ZBCPs in tunneling experiments. However, all these effects are essentially the enhancement of local Andreev reflections due to various mechanisms at the interface between a normal lead and a superconductor.…”

Section: Introductionmentioning

confidence: 99%

Majorana fermion induced nonlocal current correlations in spin-orbit coupled superconducting wires

2013

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Recent observation of zero bias conductance peaks in semiconductor wire/superconductor heterostructures has generated great interest, and there is a hot debate on whether the observation is associated with Majorana fermions (MFs). Here we study the local and crossed Andreev reflections of two normal leads attached to the two ends of a superconductor-semiconductor wire. We show that the MFs induced crossed Andreev reflections have significant effects on the shot noise of the device and strongly enhance the current-current correlations between the two normal leads. The measurements of shot noise and current-current correlations can be used to identify MFs.

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Section: Introductionmentioning

confidence: 99%

Majorana fermion induced nonlocal current correlations in spin-orbit coupled superconducting wires

2013

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“…However, most of the work so far has focused on the detection of the MFs in these nanowires and not on their bulk properties. This is quite surprising given the fact that the unambiguous identification of MFs from transport data alone can be challenging [35][36][37][38][39][40][41][42][43]. It is thus of great interest to look for alternative signatures of topological phases and to address the question how the bulk states change when passing from trivial to topological phase and if these changes appear in physically observable quantities.…”

mentioning

confidence: 99%

Spin and charge signatures of topological superconductivity in Rashba nanowires

Szumniak¹,

Chevallier²,

Loss³

et al. 2017

Phys. Rev. B

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We consider a Rashba nanowire with a proximity gap which can be brought into the topological phase by tuning external magnetic field or chemical potential. We study spin and charge of the bulk quasiparticle states when passing through the topological transition for open and closed systems. We show, analytically and numerically, that the spin of bulk states around the topological gap reverses its sign when crossing the transition due to band inversion, independent of the presence of Majorana fermions in the system. This spin reversal can be considered as a bulk signature of topological superconductivity that can be accessed experimentally. We find a similar behavior for the charge of the bulk quasiparticle states, also exhibiting a sign reversal at the transition. We show that these signatures are robust against random static disorder. DOI: 10.1103/PhysRevB.96.041401Introduction. Topological phases of condensed matter systems [1,2] have attracted a lot of attention over many years due to their high promise for applications such as topological quantum computation [3,4]. One of the hallmarks of such phases, in particular of topological superconductivity, are zero-energy modes such as Majorana fermions (MF) that emerge at the edges of the system. Various candidate materials can host such topological states [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] but one of the most promising platforms are semiconducting nanowires of InAs or InSb material, with strong Rashba spin orbit interaction (SOI), subjected to an external magnetic field and in proximity to an s-wave superconductor [22,23]. Experimental evidence has been reported for topological phases in such wires [24][25][26][27][28][29][30][31] as well as in magnetic atomic chains on superconducting substrates [32][33][34]. However, most of the work so far has focused on the detection of the MFs in these nanowires and not on their bulk properties. This is quite surprising given the fact that the unambiguous identification of MFs from transport data alone can be challenging [35][36][37][38][39][40][41][42][43]. It is thus of great interest to look for alternative signatures of topological phases and to address the question how the bulk states change when passing from trivial to topological phase and if these changes appear in physically observable quantities.In this work, we show that the phase of a topological superconductor can be monitored by bulk states, in particular by certain spin and charge degrees of freedom. Quite remarkably, we find that the sign of the spin component along the magnetic field reverses for low-momentum states close to the Fermi level when the system passes through the phase transition, and similarly for the charge of such bulk states. This sign reversal is a direct consequence of the band inversion at the transition point and is directly accessible by spin-and energy resolved measurements. Another remarkable feature is that this signature is independent of boundary effects and thus unrelated to the presence of MFs. To demons...

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“…Recently experiments on the nanowires have been carried out with the results supporting the existence the Majorana modes [9][10][11]. While loophole-free evidence still awaits [12][13][14][15][16], it seems plausible that Majorana modes will become a reality.…”

Section: Introductionmentioning

confidence: 99%

Kitaev spin models from topological nanowire networks

2014

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We show that networks of superconducting topological nanowires can realize the physics of exactly solvable Kitaev spin models on trivalent lattices. This connection arises from the low-energy theory of both systems being described by a tight-binding model of Majorana modes. In Kitaev spin models the Majorana description provides a convenient representation to solve the model, whereas in an array of Josephson junctions of topological nanowires it arises from localized physical Majorana modes tunneling between the wire ends. We explicitly show that an array of junctions of three wires-a setup relevant to topological quantum computing with nanowires-can realize the Yao-Kivelson model, a variant of Kitaev spin models on a decorated honeycomb lattice. Employing properties of the latter, we show that the network can be constructed to give rise to two-dimensional collective topological states characterized by Chern numbers ν = 0, ±1, and ±2, and that defects in the array can be associated with vortex-like quasiparticle excitations. In addition we show that the collective states are stable in the presence of disorder and superconducting phase fluctuations. When the network is operated as a quantum information processor, the connection to Kitaev spin models implies that decoherence mechanisms can in general be understood in terms of proliferation of the vortex-like quasiparticles.

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Zero-Bias Anomaly in a Nanowire Quantum Dot Coupled to Superconductors

Cited by 362 publications

References 29 publications

Majorana fermion induced nonlocal current correlations in spin-orbit coupled superconducting wires

Majorana fermion induced nonlocal current correlations in spin-orbit coupled superconducting wires

Spin and charge signatures of topological superconductivity in Rashba nanowires

Kitaev spin models from topological nanowire networks

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