Out-of-phase Andreev transports in a double-quantum-dot Cooper-pair splitter

Abstract

We investigate the Andreev transports through a double-quantum-dot Cooper-pair splitter with an additional direct coupling between the dots. It is found that when finite magnetic flux is applied through this structure, its induced phase adjusts the local and crossed Andreev reflections in different manners. Moreover, in the presence of appropriate magnetic flux, the crossed Andreev reflection can be efficiently enhanced, accompanied by the suppression of the local Andreev reflection. Such a result exists in both the linear and nonlinear transport regions, even in the case of strong intradot Coulomb interaction. Therefore, such a work provides a promising scheme to enhance the splitting of the Cooper pair.

Splitting efficiency and interference effects in a Cooper pair splitter based on a triple quantum dot with ferromagnetic contacts

“…One can generally expect an enhancement of CAR processes when the magnetic configuration changes from the parallel to the antiparallel one, since then the nonlocal processes are mainly determined by a fast majority spin channel, while the local processes are slower because they depend on the minority spin subband [32,57]. However, it turns out that this rule can depend on the position of dots' levels and interference effects [16,17,30,34,40,58]. Quantum interference can in fact make the situation quite counterintuitive and re- verse the role of CAR and DAR processes, as we discuss below.…”

“…The transport properties of quantum-dot-based CPS are already relatively well understood [13,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Such systems can be modeled by a double quantum dot Anderson-type Hamiltonian, with the two dots coupled to a common superconducting lead and each dot attached to a normal electrode.…”

Well-defined Fano effect in the Andreev reflection process of a parallel double-quantum-dot structure

“…Using the Heisenberg equation of motion, the current can be rewritten as J = −e j,kσ [V jk G < jk,σ (t, t) + c.c], where G < jk,σ (t, t ) = i c † kσ (t )d jσ (t) is the lesser Green's function. With the help of the Langreth continuation theorem and taking the Fourier transformation, we have [44]…”

Quantum transport through a quantum dot side-coupled to a Majorana bound state pair in the presence of electron-phonon interaction

“…A Y-shaped junction device consisting of two metallic leads, each connected to a SC electrode through two QDs, played the role of a Cooper-pair splitter and allowed control over CAR and LAR processes when tuning the gate voltages [73]. The Andreev transport properties of the double-QD Cooper-pair splitters [74][75][76][77] or multi-QD-MBSs setups [78][79][80][81][82][83][84][85] have also been theoretically explored. These systems show more complicated transport behavior due to quantum interference and many system parameters [79,85] and provide a feasible platform to probe MBSs [85].…”