Fano interference and a slight fluctuation of the Majorana hallmark

Abstract

Articles you may be interested inQuantum transport through the system of parallel quantum dots with Majorana bound states J. Appl. Phys. 115, 083706 (2014) (2011)], an isolated Majorana state bound to one edge of a long enough Kitaev chain in the topological phase and connected to a quantum dot, results in a robust transmittance of 1/2 at zero-bias. In this work, we show that the removal of such a hallmark can be achieved by using a metallic surface hosting two adatoms in a scenario where there is a lack of symmetry in the Fano effect, which is feasible by coupling the Kitaev chain to one of these adatoms. Thus in order to detect this feature experimentally, one should apply the following two-stage procedure: (i) first, attached to the adatoms, one has to lock AFM tips in opposite gate voltages (symmetric detuning of the levels De) and measure by an STM tip, the zero-bias conductance; (ii) thereafter, the measurement of the conductance is repeated with the gates swapped. For jDej away from the Fermi energy and in the case of strong coupling tip-host, this approach reveals in the transmittance, a persistent dip placed at zero-bias and immune to the aforementioned permutation, but characterized by an amplitude that fluctuates slightly around 1/2. However, in the case of a tip acting as a probe, the adatom decoupled from the Kitaev chain becomes completely inert and no fluctuation is observed. Therefore, the STM tip must be considered in the same footing as the "hostþadatoms" system. As a result, we have found that despite the small difference between these two Majorana dips, the zero-bias transmittance as a function of the symmetric detuning yields two distinct behaviors, in which one of them is unpredictable by the standard Fano's theory. Therefore, to access such a non trivial pattern of Fano interference, the hypothesis of the STM tip acting as a probe should be discarded. V C 2014 AIP Publishing LLC.

Probing the antisymmetric Fano interference assisted by a Majorana fermion

“…7 as can be seen in panels (a) and (b) of the same figure. Thus the ZBA is a Majorana dip that drops to above or below 1/2 depending on the sign of De: A detailed discussion on the mechanism of such a fluctuation is addressed in Ref. 13 for an analogous Scanning Tunneling Microscope system. To remove this instability of the Majorana fingerprint, the QD 2 should be discarded by keeping e M ¼ 10 À7 as shown in Figs.…”

“…In such conditions, p-wave superconductivity is induced on the nanowire due to the so-called proximity effect. [5][6][7] In the context of quantum transport, [8][9][10][11][12][13][14][15][16][17][18][19] in particular for a single quantum dot (QD) hybridized with a Majorana bound state (MBS), a zero-bias anomaly (ZBA) 11,12 in the conductance is predicted to appear, given by G ¼ 0:5G 0 , where G 0 ¼ e 2 =h is the quantum of conductance. The ZBA has been observed experimentally in conductance measurements through a nanowire of indium antimonide merged to gold and niobium titanium nitride.…”

Spin-sensitive interference due to Majorana state on the interface between normal and superconducting leads

“…1). In the case when both external leads are metallic it has been predicted reduction (by half) of the quantum dot conductance 32 , suppression of the Seebeck coefficient (due to perfect particle-hole symmetry at the Fermi level) 33 and unique interferometric lineshapes [34][35][36][37][38][39] .…”

Majorana oscillations modulated by Fano interference and degree of nonlocality in a topological superconducting-nanowire–quantum-dot system

“…First, at eV = 0, G = e 2 /2h and is independent on the values of |λ 1 | and applied field B. Moreover, differential conductance as function of bias-voltage reveals fractional Fano-like resonances around eV = 0 with intriguing minimal and maximal values equal to e 2 /4h and 3e 2 /4h 31,38 . Similar fractional Fano interference process was already reported by Barański et al 32 in a T-shaped geometry with a QD between metallic and superconducting leads, side-coupled to a MBS.…”