Hybrid system composed by a semiconducting nanowire with proximity-induced superconductivity and a quantum dot at the end working as spectrometer was recently used to quantify the so-called degree of Majorana nonlocality [Deng et al., Phys.Rev.B, 98, 085125 (2018)]. Here we demonstrate that spin-resolved density of states of the dot responsible for zero-bias conductance peak strongly depends on the separation between the Majorana bound states (MBSs) and their relative couplings with the dot and investigate how the charging energy affects the spectrum of the system in the distinct scenarios of Majorana nonlocality (topological quality). Our findings suggest that spinresolved spectroscopy of the local density of states of the dot can be used as a powerful tool for discriminating between different scenarios of the emergence of zero-bias conductance peak. arXiv:1811.10305v2 [cond-mat.mes-hall]

We investigate theoretically thermal and electrical conductances for the system consisting of a quantum dot (QD) connected both to a pair of Majorana fermions residing at the edges of a Kitaev wire and two metallic leads. We demonstrate that both quantities reveal pronounced resonances, whose positions can be controlled by tuning of an asymmetry of the couplings of the QD and a pair of MFs. Similar behavior is revealed for the thermopower, Wiedemann-Franz law and dimensionless thermoelectric figure of merit. The considered geometry can thus be used as a tuner of heat and charge transport assisted by MFs.

The Aharonov-Bohm-Fano interferometer as a spin-manipulating device J. Appl. Phys. 109, 074315 (2011); 10.1063/1.3559270 Coulomb-modified equilibrium and nonequilibrium properties in a double quantum dot Aharonov-Bohm-Fano interference device J. Appl. Phys. 107, 073702 (2010); 10.1063/1.3311641 Impurity-modified Fano effect in a double quantum dot Aharonov-Bohm interferometerAs the Fano effect is an interference phenomenon where tunneling paths compete for the electronic transport, it becomes a probe to catch fingerprints of Majorana fermions lying on condensed matter systems. In this work, we benefit of this mechanism by proposing as a route for that an Aharonov-Bohm-like interferometer composed by two quantum dots, being one of them coupled to a Majorana bound state, which is attached to one of the edges of a semi-infinite Kitaev wire within the topological phase. By changing the Fermi energy of the leads and the symmetric detuning of the levels for the dots, we show that opposing Fano regimes result in a transmittance characterized by distinct conducting and insulating regions, which are fingerprints of an isolated Majorana quasiparticle. Furthermore, we show that the maximum fluctuation of the transmittance as a function of the detuning is half for a semi-infinite wire, while it corresponds to the unity for a finite system. The setup proposed here constitutes an alternative experimental tool to detect Majorana excitations. V C 2014 AIP Publishing LLC. [http://dx.

We explore theoretically the influence of Fano interference in the so-called Majorana oscillations in a T-shaped hybrid setup formed by a quantum dot (QD) placed between conducting leads and sidecoupled to a topological superconducting nanowire (TSNW) hosting zero-energy Majorana bound states (MBSs) at the ends. Differential conductance as a function of the external magnetic field reveals oscillatory behavior. Both the shape and amplitude of the oscillations depend on the biasvoltage, degree of MBSs non-locality and Fano parameter of the system determining the regime of interference. When the latter is such that direct lead-lead path dominates over lead-QD-lead path and the bias is tuned in resonance with QD zero-energy, pronounced fractional Fano-like resonances are observed around zero-bias for highly non-local geometries. Further, the conductance profiles as a function of both bias-voltage and QD energy level display "bowtie" and "diamond" shapes, in qualitative agreement with both previous theoretical and experimental works. These findings ensure that our proposal can be used to estimate the degree of MBS non-locality, thus allowing to investigate their topological properties. arXiv:1802.07106v2 [cond-mat.mes-hall] 30 Sep 2018 wherein H o = k ε k c † o,k c o,k −V SD k,q c † o,k c o,q describes the odd conduction states, which are decoupled from the QD 9 .The term 34

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We theoretically investigate a topological Kitaev chain connected to a double quantum-dot (QD) setup hybridized with metallic leads. In this system, we observe the emergence of two striking phenomena: i) a decrypted Majorana Fermion (MF)-qubit recorded over a single QD, which is detectable by means of conductance measurements due to the asymmetrical MF-leaked state into the QDs; ii) an encrypted qubit recorded in both QDs when the leakage is symmetrical. In such a regime, we have a cryptographylike manifestation, since the MF-qubit becomes bound states in the continuum, which is not detectable in conductance experiments. PACS numbers: 72.10.Fk 73.63.Kv 74.20.MnIntroduction.-It is well known that Majorana fermions (MFs) zero-modes [1,2] are expected to appear bounded to the edges of a topological Kitaev chain [3][4][5][6][7]. Interestingly enough, by approaching the Kitaev chain to a quantum dot (QD), the MF state leaks[8] into it and manifests itself as a zero-bias peak (ZBP) in conductance measurements. The latter reveals experimentally the MF-qubit recorded over the QD. Indeed, such a phenomenon was experimentally confirmed in a QD hybridnanowire made by InAs/Al[9] with huge spin-orbit interaction and magnetic fields, being the nanowire placed close to an s-wave superconductor. It is worth mentioning that MFs can also emerge in the fractional quantum Hall state with filling-factor ν = 5/2[10], in threedimensional topological insulators [11], at the core of superconducting vortices [12][13][14] and on the edges of ferromagnetic atomic chains covering superconductors with pronounced spin-orbit interaction [15,16], similarly to semiconducting nanowires [17]. In terms of technological applications, MFs-qubits are of particular interest. This is because of their topological protection against decoherence[3], a key ingredient for the achievement of efficient quantum computers.In this work, we show that the employment of two QDs, as depicted in Fig.1(a), enables the cryptography of the MF-qubit state η ↑ = 1

We explore theoretically the formation of bound states in the continuum (BICs) in graphene hosting two collinear adatoms situated at different sides of the sheet and at the center of the hexagonal cell, where a phantom atom of a fictitious lattice emulates the six carbons of the cell. We verify that in this configuration the local density of states (LDOS) near the Dirac points exhibits two characteristic features: i) the cubic dependence on energy instead of the linear one for graphene as found in New J. Phys. 16, 013045 (2014) and ii) formation of BICs as aftermath of a Fano destructive interference assisted by the Coulomb correlations in the adatoms. For the geometry where adatoms are collinear to carbon atoms, we report absence of BICs.

We report on a theoretical investigation of the interplay between vacuum fluctuations, Majorana quasiparticles (MQPs) and bound states in the continuum (BICs) by proposing a new venue for qubit storage. BICs emerge due to quantum interference processes as the Fano effect and, since such a mechanism is unbalanced, these states decay as regular into the continuum. Such fingerprints identify BICs in graphene as we have discussed in detail in Phys. Rev. B 92, 245107 and 045409 (2015). Here by considering two semi-infinite Kitaev chains within the topological phase, coupled to a quantum dot (QD) hybridized with leads, we show the emergence of a novel type of BICs, in which MQPs are trapped. As the MQPs of these chains far apart build a delocalized fermion and qubit, we identify that the decay of these BICs is not connected to Fano and it occurs when finite fluctuations are observed in the vacuum composed by electron pairs for this qubit. From the experimental point of view, we also show that vacuum fluctuations can be induced just by changing the chain-dot couplings from symmetric to asymmetric. Hence, we show how to perform the qubit storage within two delocalized BICs of MQPs and to access it when the vacuum fluctuates by means of a complete controllable way in quantum transport experiments.