Probing Majorana-like states in quantum dots and quantum rings

Scharf, Benedikt; Žutić, Igor

doi:10.1103/physrevb.91.144505

Cited by 19 publications

(15 citation statements)

References 106 publications

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“…where η represents an effective shift in the chemical potential due to local changes of the magnetic texture. For a homogeneous B-field, η → 0, this generalized topological condition reduces to the previous one determining the topological transition in quantum wires and rings [47,48,56,57]. If we rewrite Eq.…”

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confidence: 98%

“…In addition to ZES, the existence of MBS can also be supported by the spatially localized probability density, |Ψ| 2 = |u| 2 + |v| 2 , and a neutral charge density, ρ = |u| 2 -|v| 2 , where u and v are particle and hole components of its wavefunction, respectively [56,57,73]. For comparison, we calculate |Ψ| 2 and ρ of both topological (µ = 0) and trivial states (µ = 0.4 meV).…”

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confidence: 99%

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Tunable magnetic textures in spin valves: From spintronics to Majorana bound states

et al. 2019

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Spin-valve structures in which a change of magnetic configuration is responsible for magnetoresistance led to impressive advances in spintronics, focusing on magnetically storing and sensing information. However, this mature technology also offers versatile control of magnetic textures with usually neglected underlying fringing fields to enable entirely different applications by realizing topologically-nontrivial states. Together with proximity-induced superconductivity in a two-dimensional electron gas with a large g-factor, these fringing fields realized in commercially-available spin valves provide Zeeman splitting, synthetic spin-orbit coupling, and confinement, needed for Majorana bound states (MBS). Detailed support for the existence and control of MBS is obtained by combining accurate micromagnetic simulation of fringing fields used as an input in Bogoliubov de Gennes equation to calculate low-energy spectrum, wavefunction localization, and local charge neutrality. A generalized condition for a quantum phase transition in these structures provides valuable guidance for the MBS evolution and implementing reconfigurable effective topological wires.

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confidence: 98%

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confidence: 99%

Tunable magnetic textures in spin valves: From spintronics to Majorana bound states

et al. 2019

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“…Observed MBS signatures, such as a zero-bias tunneling conductance peak, may have other origins [31][32][33][34][35] and should be supplemented by additional measurements [36][37][38][39][40]. However, those signatures do not directly probe non-Abelian statistics [2][3][4]8].…”

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confidence: 99%

Wireless Majorana Bound States: From Magnetic Tunability to Braiding

et al. 2016

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We propose a versatile platform to investigate the existence of Majorana bound states (MBSs) and their nonAbelian statistics through braiding. This implementation combines a two-dimensional electron gas formed in a semiconductor quantum well grown on the surface of an s-wave superconductor, with a nearby array of magnetic tunnel junctions (MTJs). The underlying magnetic textures produced by MTJs provide highly-controllable topological phase transitions to confine and transport MBSs in two dimensions, overcoming the requirement for a network of wires. Obtained scaling relations confirm that various semiconductor quantum well materials are suitable for this proposal. PACS numbers: 74.78.Na,74.25.Ha,74.45.+c In condensed-matter systems Majorana bound states (MBSs) are emergent quasiparticles with exotic non-Abelian statistics and particle-antiparticle symmetry [1][2][3][4][5][6][7]. Elucidating their properties is further motivated by the prospect to use them for fault-tolerant quantum computing [8][9][10]. Typical material systems envisioned for experimental implementations of MBSs include superconducting regions [11] such as those relying on the native p-wave pairing in a vortex core [12], Sr 2 RuO 4 [13,14], and Bechgaard salts [15]. They can also occur with common proximity-induced s-wave pairing when combined with a nontrivial spin structure, which can be provided by spin-orbit coupling (SOC) and magnetic textures [16][17][18][19][20][21][22][23][24] to yield an effective p-wave pairing.Impressive advances in fabricating complex superconducting systems for an unambiguous detection of MBSs remain actively debated [23,[25][26][27][28][29][30]. Observed MBS signatures, such as a zero-bias tunneling conductance peak, may have other origins [31][32][33][34][35] and should be supplemented by additional measurements [36][37][38][39][40]. However, those signatures do not directly probe non-Abelian statistics [2][3][4]8]. While realizing the non-Abelian braiding statistics under exchange would provide both an ultimate proof for the MBS existence and the key element for topological quantum computing, even theoretical schemes imply a significant complexity to implement such braiding [10]. Exchanging vortices on the surface of the p-wave superconductor to close the braiding loop would require an experimental tour de force. Frequently examined one-dimensional (1D) superconductor/semiconductor wire systems avoid the need for challenging vortex manipulation, but that geometry alone is insufficient. Braiding statistics are ill-defined in 1D and complex wire networks must be used instead of single wires, posing additional obstacles [10,41].To address these challenges, in Fig. 1 we propose a versatile platform to realize MBSs and enable their braiding in 2D superconductor/semiconductor systems without the need for wire networks. This proposal seemingly contradicts prior knowledge. In semiconductor wires with SOC-based effective p-wave pairing, the energetically isolated MBSs do not survive the transition to 2D, but rather ev...

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“…Very recently, appearance of the absorption peak at B = B c in magnetooptical conductivity has been theoretically predicted by Scharf et al [26]. By using the Bernevig-Hughes-Zhang model [10] proposed for HgTe QWs, they have calculated optical conductivity in the presence of perpendicular magnetic field.…”

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confidence: 94%

Observation of topological phase transition by terahertz photoconductivity in HgTe‐based transistors

Kadykov

Consejo

Marcinkiewicz

et al. 2016

Phys. Status Solidi C

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We have found the possibility to probe the magnetic field‐driven topological phase transition in HgTe‐based transistors by measuring their Terahertz photoconductivity response. At the critical magnetic field to which zero‐mode Landau levels cross, we have observed a pronounced photoconductivity peak independent on incident frequency and carrier concentration. Our results pave the way towards terahertz topological field effect transistors. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Probing Majorana-like states in quantum dots and quantum rings

Cited by 19 publications

References 106 publications

Tunable magnetic textures in spin valves: From spintronics to Majorana bound states

Tunable magnetic textures in spin valves: From spintronics to Majorana bound states

Wireless Majorana Bound States: From Magnetic Tunability to Braiding

Observation of topological phase transition by terahertz photoconductivity in HgTe‐based transistors

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