Non-Abelian topological superconductors from topological semimetals and related systems under the superconducting proximity effect

Jiang, Jianhua; Wu, Si

doi:10.1088/0953-8984/25/5/055701

Cited by 28 publications

(27 citation statements)

References 52 publications

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“…Topological superconductivity (TSC) hosting exotic zero-energy Majorana excitations has become an area of intense research, both theoretically and experimentally, over the past decade [1][2][3][4][5][6][7][8][9][10][11][12]. The most-studied realization of one-dimensional TSC is a strongly spinorbit-coupled (SOC) semiconducting nanowire in proximity to a conventional s-wave superconductor (SC) and in the presence of an external Zeeman field [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire

Liu

Stãnescu

et al. 2019

Phys. Rev. B

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In a recent high-quality experimental work on normal metal-superconducting nanowire junctions [J.D.S. Bommer et al., arXiv:1807.01940 (2018], strong anisotropic suppression of induced superconductivity has been observed in tunnel conductance measurements in the presence of applied magnetic field with variable orientation. Following this finding, we investigate theoretically the dependence of tunnel conductance on the direction of the Zeeman field in order to understand the operational mechanisms and to extract effective system parameters. Second, motivated by a generic discrepancy between experiment and theory, i.e., many in-gap and above-gap conductance features predicted by theory are barely observed in experiments, we study several mechanisms possibly responsible for the suppression of the theoretically predicted conductance features (e.g., length of the nanowire, self-energy effect due to the proximity effect, finite temperature, finite dissipation, and multiband effect). One essential finding in the current work is that only by a combined understanding of both suppression mechanisms can we extract effective system parameters from the experimental data (e.g., the effective nanowire-superconductor coupling, the effective Landé g factor, and the chemical potential of the semiconducting nanowire). In addition, we consider topologically trivial Andreev bound states in hybrid nanowires in the presence of potential inhomogeneities, such as external quantum dots or potential inhomogeneities inside the nanowire. We compare the anisotropic, fielddependent features induced by these nontopological Andreev bound states with the corresponding features produced by topological Majorana zero modes in pristine nanostructures, so that we can provide guidance to differentiate between the topologically trivial and nontrivial cases. arXiv:1811.11504v2 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire

Liu

Stãnescu

et al. 2019

Phys. Rev. B

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“…Hybrid nanostructures combining spin-orbit coupled semiconducting nanowires and conventional superconductivity are a promising candidate to host Majorana bound states (MBS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Much of the ongoing experimental work on these devices relies on two-terminal tunnel spectroscopy in which the nanowires are coupled to a normal reservoir through an electrostatic tunnel barrier.…”

Section: Introductionmentioning

confidence: 99%

Conductance asymmetries in mesoscopic superconducting devices due to finite bias

et al. 2021

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Tunneling conductance spectroscopy in normal metal-superconductor junctions is an important tool for probing Andreev bound states in mesoscopic superconducting devices, such as Majorana nanowires. In an ideal superconducting device, the subgap conductance obeys specific symmetry relations, due to particle-hole symmetry and unitarity of the scattering matrix. However, experimental data often exhibits deviations from these symmetries or even their explicit breakdown. In this work, we identify a mechanism that leads to conductance asymmetries without quasiparticle poisoning. In particular, we investigate the effects of finite bias and include the voltage dependence in the tunnel barrier transparency, finding significant conductance asymmetries for realistic device parameters. It is important to identify the physical origin of conductance asymmetries: in contrast to other possible mechanisms such as quasiparticle poisoning, finite-bias effects are not detrimental to the performance of a topological qubit. To that end we identify features that can be used to experimentally determine whether finite-bias effects are the source of conductance asymmetries.

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“…Majorana zero modes (MZMs) are neutral midgap excitations localized at the defects or wire ends of a topological superconductor [1][2][3][4][5][6][7][8][9][10][11][12]. Due to their robustness against local perturbations and their non-Abelian statistics, MZMs are potential building blocks for topological quantum computation [13,14].…”

Section: Introductionmentioning

confidence: 99%

Josephson current via an isolated Majorana zero mode

2021

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We study the equilibrium dc Josephson current in a junction between an s-wave and a topological superconductor. Cooper pairs from the s-wave superconducting lead can transfer to the topological side either via an unpaired Majorana zero mode localized near the junction or via the above-gap continuum states. We find that the Majorana contribution to the supercurrent can be switched on when time-reversal symmetry in the conventional lead is broken, e.g., by an externally applied magnetic field inducing a Zeeman splitting. Moreover, if the magnetic field has a component in the direction of the effective spin-orbit field, there will be a Majorana-induced anomalous supercurrent at zero phase difference. These behaviors may serve as a signature characteristic of Majorana zero modes and are accessible to devices with only superconducting contacts.

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Non-Abelian topological superconductors from topological semimetals and related systems under the superconducting proximity effect

Cited by 28 publications

References 52 publications

Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire

Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire

Conductance asymmetries in mesoscopic superconducting devices due to finite bias

Josephson current via an isolated Majorana zero mode

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