Abstract
We characterize parallel double quantum dot Josephson junctions based on closely-grown double nanowires bridged by in-situ deposited superconductors. The parallel double dot behavior occurs despite the closeness of the nanowires and the potential risk of nanowire clamping during growth. By tuning the charge filling and lead couplings, we map out the simplest parallel double quantum dot Yu-Shiba-Rusinov phase diagram. Our quasi-independent two-wire hybrids show promise for the realization of exotic topological phases.
Highlights
Double Rashba-nanowires bridged by superconductors are at the center of proposals for qubits [1], coupled subgap states [2], and exotic topological superconducting phases based on Majorana zero modes (MZMs) [3,4,5,6,7,8,9,10,11,12,13,14,15,16]
As a guide to the different ground state (GS) configurations accessed in this paper, we show in Fig. 1(e) a sketch of the phase diagram of the parallel double quantum dot (DQD) Josephson junctions (JJs) versus coupling to the leads when the two quantum dots (QDs) have independent GSs
We have demonstrated parallel QD JJs fabricated out of a double-nanowire platform in which the nanowires are bridged by an in-situ deposited superconductor
Summary
Double Rashba-nanowires bridged by superconductors are at the center of proposals for qubits [1], coupled subgap states [2], and exotic topological superconducting phases based on Majorana zero modes (MZMs) [3,4,5,6,7,8,9,10,11,12,13,14,15,16]. Researchers have theorized on the existence of a topological Kondo phase in such wires when the bridging superconductor is in Coulomb blockade [3,4,15,17] and, more recently, described a device hosting parafermions [6] Realization of these proposals should benefit from material science developments, resulting in improved nanowire-superconductor interfaces with low quasiparticle poisoning rates [18,19,20]. YSR states, belonging to the class of Andreev bound states [23,24,25,27,28,29,30,31,32,33,34,35,36,37,38,39], arise in the limit of large Coulomb charging energy, U > , as a result of the virtual excitation of a quasiparticle into the edge of the superconducting gap [40,41]. V we present our conclusions and provide perspectives of our paper
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