References of "Schmidt, Thomas 50008497"
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See detailGeneric Helical Liquids: Theory & Applications
Rod, Alexia UL; Dolcetto, Giacomo UL; Rachel, Stephan et al

Poster (2016, August 23)

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See detailTransport through a quantum spin Hall antidot as a spectroscopic probe of spin textures
Rod, Alexia UL; Dolcetto, Giacomo UL; Rachel, Stephan et al

in Physical Review. B (2016), 94

We investigate electron transport through an antidot embedded in a narrow strip of two-dimensional topological insulator. We focus on the most generic and experimentally relevant case with broken axial ... [more ▼]

We investigate electron transport through an antidot embedded in a narrow strip of two-dimensional topological insulator. We focus on the most generic and experimentally relevant case with broken axial spin symmetry. Spin-non-conservation allows additional scattering processes which change the transport properties profoundly. We start from an analytical model for noninteracting transport, which we also compare with a numerical tight-binding simulation. We then extend this model by including Coulomb repulsion on the antidot, and we study the transport in the Coulomb-blockade limit. We investigate sequential tunneling and cotunneling regimes, and we find that the current-voltage characteristic allows a spectroscopic measurement of the edge-state spin textures. [less ▲]

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See detailSpin textures and response functions of helical electron systems
Schmidt, Thomas UL

Scientific Conference (2016, July)

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See detailThe helical gap in interacting Rashba wires at low electron densities
Schmidt, Thomas UL; Pedder, Christopher UL

E-print/Working paper (2016)

Rashba spin-orbit coupling and a magnetic field perpendicular to the Rashba axis have been predicted to open a partial gap ("helical gap") in the energy spectrum of noninteracting or weakly interacting ... [more ▼]

Rashba spin-orbit coupling and a magnetic field perpendicular to the Rashba axis have been predicted to open a partial gap ("helical gap") in the energy spectrum of noninteracting or weakly interacting one-dimensional quantum wires. By comparing kinetic energy and Coulomb energy we show that this gap opening typically occurs at low electron densities where the Coulomb energy dominates. To address this strongly correlated limit, we investigate Rashba wires using Wigner crystal theory. We find that the helical gap exists even in the limit of strong interactions but its dependence on electron density differs significantly from the weakly interacting case. In particular, we find that the critical magnetic field for opening the gap becomes an oscillatory function of electron density. [less ▲]

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See detailThe topological Anderson insulator phase in the Kane-Mele model
Orth, Christoph; Sekera, Tibor; Bruder, Christoph et al

in Scientific Reports (2016), 6

It has been proposed that adding disorder to a topologically trivial mercury telluride/cadmium telluride (HgTe/CdTe) quantum well can induce a transition to a topologically nontrivial state. The resulting ... [more ▼]

It has been proposed that adding disorder to a topologically trivial mercury telluride/cadmium telluride (HgTe/CdTe) quantum well can induce a transition to a topologically nontrivial state. The resulting state was termed topological Anderson insulator and was found in computer simulations of the Bernevig-Hughes-Zhang model. Here, we show that the topological Anderson insulator is a more universal phenomenon and also appears in the Kane-Mele model of topological insulators on a honeycomb lattice. We numerically investigate the interplay of the relevant parameters, and establish the parameter range in which the topological Anderson insulator exists. A staggered sublattice potential turns out to be a necessary condition for the transition to the topological Anderson insulator. For weak enough disorder, a calculation based on the lowest-order Born approximation reproduces quantitatively the numerical data. Our results thus considerably increase the number of candidate materials for the topological Anderson insulator phase. [less ▲]

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See detailStrongly interacting quantum wires with spin-orbit coupling
Pedder, Christopher UL; Schmidt, Thomas UL

Scientific Conference (2016, March 10)

We study the effect of Rashba spin-orbit coupling on a quantum wire with strong interactions, which can be experimentally realised by depopulating a gated InSb or GaAs wire. When the wire carries a very ... [more ▼]

We study the effect of Rashba spin-orbit coupling on a quantum wire with strong interactions, which can be experimentally realised by depopulating a gated InSb or GaAs wire. When the wire carries a very low density of electrons, it is convenient to model the system in terms of a "Wigner crystal" of electrons localised on lattice sites. At the lowest densities, the Wigner crystal is a one dimensional entity, whereas at intermediate regimes it is know that a "zigzag" crystal consisting of two parallel rows of electrons can form. We investigate the effect of Rashba spin-orbit coupling, which plays an important role for both the spin and charge degrees of freedom, in both these systems with and without an applied magnetic field. We propose detection of these effects via measurement of spin-spin correlation functions of the quantum wire, e.g. by doing STM with a polarized tip. [less ▲]

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See detailProbing the spin texture of generic helical edge states with an antidot
Rod, Alexia UL; Dolcetto, Giacomo UL; Rachel, Stephan et al

Scientific Conference (2016, March 07)

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See detailParafermions in time-reversal invariant topological insulators
Schmidt, Thomas UL

Scientific Conference (2016, January)

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See detailDetecting and manipulating Majorana bound states in nanowires
Schmidt, Thomas UL

Presentation (2016, January)

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See detailParafermions in 2D topological insulators
Schmidt, Thomas UL

Presentation (2016, January)

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See detailHelical edge states of two-dimensional topological insulators
Schmidt, Thomas UL

Presentation (2016, January)

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See detailDetecting and manipulating Majorana bound states in nanowires
Schmidt, Thomas UL

Scientific Conference (2016)

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See detailEdge physics in two-dimensional topological insulators
Dolcetto, Giacomo UL; Sassetti, Maura; Schmidt, Thomas UL

in La Rivista del Nuovo Cimento (2016)

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See detailHelical gaps in interacting {Rashba} wires at low electron densities
Schmidt, Thomas UL; Pedder, Christopher

in Physical Review. B, Condensed Matter (2016), 94

Rashba spin-orbit coupling and a magnetic field perpendicular to the Rashba axis have been predicted to open a partial gap (“helical gap”) in the energy spectrum of noninteracting or weakly interacting ... [more ▼]

Rashba spin-orbit coupling and a magnetic field perpendicular to the Rashba axis have been predicted to open a partial gap (“helical gap”) in the energy spectrum of noninteracting or weakly interacting one-dimensional quantum wires. By comparing kinetic energy and Coulomb energy we show that this gap opening typically occurs at low electron densities where the Coulomb energy dominates. To address this strongly correlated limit, we investigate Rashba wires using Wigner crystal theory. We find that the helical gap exists even in the limit of strong interactions but its dependence on electron density differs significantly from the weakly interacting case. In particular, we find that the critical magnetic field for opening the gap becomes an oscillatory function of electron density. This changes strongly the expected signature of the helical gap in conductance measurements. [less ▲]

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See detailNon local quantum state engineering with the Cooper pair splitter beyond the Coulomb blockade regime
Amitai, Ehud; Tiwari, Rakesh; Walter, Stefan et al

in Physical Review. B (2015), 93

A Cooper pair splitter consists of two quantum dots side-coupled to a conventional superconductor. Usually, the quantum dots are assumed to have a large charging energy compared to the superconducting gap ... [more ▼]

A Cooper pair splitter consists of two quantum dots side-coupled to a conventional superconductor. Usually, the quantum dots are assumed to have a large charging energy compared to the superconducting gap, in order to suppress processes other than the coherent splitting of Cooper pairs. In this work, in contrast, we investigate the limit in which the charging energy is smaller than the superconducting gap. This allows us, in particular, to study the effect of a Zeeman field comparable to the charging energy. We find analytically that in this parameter regime the superconductor mediates an inter-dot tunneling term with a spin symmetry determined by the Zeeman field. Together with electrostatically tunable quantum dots, we show that this makes it possible to engineer a spin triplet state shared between the quantum dots. Compared to previous works, we thus extend the capabilities of the Cooper pair splitter to create entangled non local electron pairs. [less ▲]

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See detailParafermion bound states and the fractional Josephson effect in Rashba spin-orbit coupled nanowires
Pedder, Christopher UL; Meng, Tobias; Tiwari, Rakesh et al

Poster (2015, September)

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See detailFull counting statistics of Majorana interferometers
Strubi, Gregory; Belzig, Wolfgang; Schmidt, Thomas UL et al

in Physica E: Low-Dimensional Systems and Nanostructures (2015), 74

We study the full counting statistics of interferometers for chiral Majorana fermions with two incoming and two outgoing Dirac fermion channels. In the absence of interactions, the FCS can be obtained ... [more ▼]

We study the full counting statistics of interferometers for chiral Majorana fermions with two incoming and two outgoing Dirac fermion channels. In the absence of interactions, the FCS can be obtained from the 4×4 scattering matrix S that relates the outgoing Dirac fermions to the incoming Dirac fermions. After presenting explicit expressions for the higher-order current correlations for a modified Hanbury Brown–Twiss interferometer, we note that the cumulant-generating function can be interpreted such that unit-charge transfer processes correspond to two independent half-charge transfer processes, or alternatively, to two independent electron-hole conversion processes. By a combination of analytical and numerical approaches, we verify that this factorization property holds for a general SO(4) scattering matrix, i.e. for a general interferometer geometry. [less ▲]

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See detailSpin-charge coupling in correlated one-dimensional quantum systems
Schmidt, Thomas UL

Scientific Conference (2015, August)

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See detail8pi-periodic Josephson effect in time-reversal invariant interacting Rashba nanowires
Pedder, Christopher UL; Meng, Tobias; Tiwari, Rakesh et al

E-print/Working paper (2015)

We investigate narrow quantum wires with strong Rashba spin-orbit coupling and electron-electron interactions. We show that virtual transitions between subbands lead to umklapp scattering which can open a ... [more ▼]

We investigate narrow quantum wires with strong Rashba spin-orbit coupling and electron-electron interactions. We show that virtual transitions between subbands lead to umklapp scattering which can open a partial gap in the spectrum even in the presence of time-reversal symmetry. Using the superconducting proximity effect to gap out the remaining modes, we show that the system can host zero-energy states at its edges, which are protected by time-reversal symmetry. We present the parameter regime in which these bound states will emerge. Similarly to Majorana bound states, they will produce a zero-bias peak in the differential conductance. In contrast to the Majorana fermions, however, their fourfold degeneracy leads to an 8π periodicity of the Josephson current due to tunneling of fractionalized excitations with charge e/2. [less ▲]

Detailed reference viewed: 166 (4 UL)