Hybrid nanowires combining semiconductor and superconductor materials appear well suited for the creation, detection, control of Majorana bound states (MBSs). We demonstrate emergence MBSs from coalescing Andreev (ABSs) in a hybrid InAs nanowire with epitaxial Al, using quantum dot at end as spectrometer. Electrostatic gating tuned density to regime one or few ABSs. In an applied axial magnetic field, topological phase emerges which ABSs move zero energy remain there, forming MBSs. observed...

This short review article provides a pedagogical introduction to the rapidly growing research field of Majorana fermions in topological superconductors. We first discuss some details simplest "toy model" which Majoranas appear, namely one-dimensional tight-binding representation p-wave superconductor, introduced more than ten years ago by Kitaev. then give general remarkable properties condensed matter systems, such as their intrinsically non-local nature and exotic exchange statistics,...

We introduce a scheme for preparation, manipulation, and readout of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances materials growth tools commonly used quantum-dot experiments, including gate-control tunnel barriers Coulomb effects, charge sensing, pumping. outline sequence milestones interpolating between zero-mode detection quantum computing that includes (1) fusion rules non-Abelian anyons using either proximal...

We present designs for scalable quantum computers composed of qubits encoded in aggregates four or more Majorana zero modes, realized at the ends topological superconducting wire segments that are assembled into islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between modes and nearby semiconductor dots. Our proposed architecture have following principal virtues: (1) magnetic...

We consider theoretically tunneling characteristic of a junction between normal metal and chain coupled Majorana bound states generated at crossings topological non-topological superconducting sections, as result of, for example, disorder in nanowires. While an isolated state supports resonant Andreev process, yielding zero bias differential conductance peak height 2e^2/h, the situation with more is distinctively different both zeros 2e^2/h peaks conductance. derive general expression...

We report an experimental study of the scaling zero-bias conductance peaks compatible with Majorana zero modes as a function magnetic field, tunnel coupling, and temperature in one-dimensional structures fabricated from epitaxial semiconductor-superconductor heterostructure. Results are consistent theory, including peak that is proportional to saturates at $2e^2/h$, decreases expected field-dependent gap, collapses onto simple dimensionless ratio coupling.

Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries, enabled by sophisticated fabrication, have uncovered new phenomena that completely change our understanding transport these devices, especially the role spin and valley degrees freedom. This review describes modern through nanotube devices. Unlike conventional semiconductors, electrons two angular momentum quantum numbers, arising from We focus on interplay between...

Quantum information protected by the topology of storage medium is expected to exhibit long coherence times. Another feature are topologically gates generated through braiding Majorana bound states. However, requires structures with branched topological segments which have inherent difficulties in semiconductor-superconductor heterostructures now believed host In this paper, we construct quantum bits taking advantage protection and non-local properties states a network parallel wires, but...

We demonstrate that non-Abelian rotations within the degenerate groundstate manifold of a set Majorana fermions can be realized by addition or removal single electrons, and propose an implementation using Coulomb blockaded quantum dots. The exchange electrons generates similar to braiding, though not in real space. Unlike braiding operations, continuum angles are possible, while still being partially robust against perturbations. dots also used for readout state system via charge measurement.

We model theoretically a two-dimensional electron gas (2DEG) covered by superconductor and demonstrate that topological superconducting channels are formed when stripes of the layer removed. As consequence, Majorana bound states (MBSs) created at ends stripes. calculate invariant energy gap single stripe, using realistic values for an InAs 2DEG proximitized epitaxial Al layer. show is enhanced structure made asymmetric. This can be achieved either imposing phase difference (by driving...

Abstract Coupling a two-dimensional (2D) semiconductor heterostructure to superconductor opens new research and technology opportunities, including fundamental problems in mesoscopic superconductivity, scalable superconducting electronics, topological states of matter. One route towards matter is by coupling 2D electron gas with strong spin–orbit interaction an s-wave superconductor. Previous efforts along these lines have been adversely affected interface disorder unstable gating. Here we...

The possibility of engineering artificial Kitaev chains in arrays quantum dots coupled via narrow superconducting regions has emerged as an attractive way to overcome the disorder issues that complicate realization and detection topological phases other platforms. Although a true phase would require long chains, two-site chain realized double dot can already be tuned points parameter space where it hosts zero-energy states seem identical Majorana bound characterize phase. These have been...

Transport through molecular devices with strong coupling to a single vibrational mode is considered in the case where vibration damped by environment. We focus on weak tunneling limit, for which rate equation approach valid. The role of environment can be characterized frictional damping term $\mysig(\omega)$ and corresponding frequency shift. consider molecule that attached substrate, leading frequency-dependent oscillator molecule, compare it reference model frequency-independent featuring...

We present corrected calculations of the subharmonic energy-gap structure using model Octavio, Tinkham, Blonder, and Klapwijk, which includes effect normal scattering in weak link. show that while overall predictions this do not change qualitatively, details predicted curves are different better agreement with experiment. also calculation current-voltage characteristics excess currents for T=0, as parameter Z is varied. how can be shortened symmetry arguments discuss improves understanding...

We show that confined Majorana fermions can exist in nanowires with proximity induced s-wave superconducting pairing if the direction of an external magnetic field rotates along wire. The system is equivalent to Rashba-type spin-orbit coupling, strength proportional derivative angle. For realistic parameters, we demonstrate a set permanent magnets bring nearby nanowire into topologically non-trivial phase localized modes at its ends. Without requirement coupling this opens up for new route...

We demonstrate an electrically controlled high-spin (S = 5/2) to low-spin 1/2) transition in a three-terminal device incorporating single Mn2+ ion coordinated by two terpyridine ligands. By adjusting the gate-voltage we reduce moiety and thereby strengthen ligand-field on Mn-atom. Adding electron thus stabilizes configuration corresponding sequential tunnelling current is suppressed spin-blockade. From low-temperature inelastic cotunneling spectroscopy, infer magnetic excitation spectrum of...

We study a double quantum dot connected via common superconducting lead and show that this system can be tuned to host one Majorana bound state (MBS) on each dot. call them "poor man's states" since they are not topologically protected, but otherwise share the properties of MBS formed in topological superconductors. describe conditions for existence two spatially separated MBS, which include breaking spin degeneracy dots, with spins polarized different directions. Therefore, we propose use...

We report on quantum dot based Josephson junctions designed specifically for measuring the supercurrent. From high-accuracy fitting of current−voltage characteristics, we determine full magnitude supercurrent (critical current). Strong gate modulation critical current is observed through several consecutive Coulomb blockade oscillations. The crosses zero close to, but not at, resonance due to so-called 0−π transition in agreement with a simple theoretical model.

We present a detailed study of the nonlinear thermoelectric properties molecular junction, represented by dissipative Anderson-Holstein model. A single-orbital level with strong Coulomb interaction is coupled to localized vibrational mode and we account for both electron phonon exchange electrodes, investigating how these contribute heat charge transports. calculate efficiency power output device operated as electric converter in regime weak tunnel coupling rate identify optimal operating...

We use charge sensing of Pauli blockade (including spin and isospin) in a two-electron 13C nanotube double quantum dot to measure relaxation dephasing times. The time, T1, first decreases with parallel magnetic field then goes through minimum 1.4 T. attribute both results the spin-orbit-modified electronic spectrum carbon nanotubes, which suppresses hyperfine mediated enhances due soft phonons. inhomogeneous T2*, is consistent previous data on coupling strength nanotubes.

We propose a setup to measure the lifetime of parity pair Majorana bound states. The proposed experiment has one edge state tunnel coupled quantum dot, which in turn is metallic electrode. When fermions overlap, even small relaxation rate qualitatively changes nonlinear transport spectrum, and for strong overlap can be read off directly from height current peak. This important usage as platform topological computing, where limiting factor.