Transport properties of double quantum dots coupled to a superconductor

Superconductor/semiconductor hybrid systems have drawn a lot of attention due to their rich physics and the potential to demonstrate topologically protected qubits. We experimentally investigate transport properties of a double dot electrostatically defined in an InAs nanowire by metallic gates under the wire. Superconductivity is provided by epitaxial Al shell grown in-situ after nanowire growth. The shell induces a hard gap and sharp spectral features of Andreev bound states in the nanowire. The source of the double dot is a normal metal while the drain is a superconductor. We study the spectra of the resulting normal-Andreev double dot and search for the recently proposed Andreev blockade upon which current is blocked in the triplet (1,1) configuration which is unable to form a Cooper pair and enter the drain superconductor.