2019-07-09T17:48:13Z, Mantovani, Mattia, Belzig, Wolfgang, Rastelli, Gianluca, Hussein, Robert

Hybrid quantum dot-oscillator systems have become attractive platforms to inspect quantum coherence effects at the nanoscale. Here, we investigate a Cooper-pair splitter setup consisting of two quantum dots, each linearly coupled to a local resonator. The latter can be realized either by a microwave cavity or a nanomechanical resonator. Focusing on the subgap regime, we demonstrate that cross-Andreev reflection, through which Cooper pairs are split into both dots, can efficiently cool down simultaneously both resonators into their ground state. Moreover, we show that a nonlocal heat transfer between the two resonators is activated when opportune resonance conditions are matched. The proposed scheme can act as a heat-pump device with potential applications in heat control and cooling of mesoscopic quantum resonators.

2017, Hussein, Robert, Braggio, Alessandro, Governale, Michele

The control of nonlocal entanglement in solid state systems is a crucial ingredient of quantum technologies. We investigate a Cooper-pair splitter based on a double quantum dot realized in a semiconducting nanowire. In the presence of interdot tunneling the system provides a simple mechanism to develop spatial entanglement even in absence of nonlocal coupling with the superconducting lead. We discuss the possibility to control the symmetry (singlet or triplet) of spatially separated, entangled electron pairs taking advantage of the spin-orbit coupling of the nanowire. We also demonstrate that the spin-orbit coupling does not impact over the entanglement purity of the nonlocal state generated in the double quantum dot system.

2019-07-09T17:48:13Z, Mantovani, Mattia, Belzig, Wolfgang, Rastelli, Gianluca, Hussein, Robert

Hybrid quantum dot-oscillator systems have become attractive platforms to inspect quantum coherence effects at the nanoscale. Here, we investigate a Cooper-pair splitter setup consisting of two quantum dots, each linearly coupled to a local resonator. The latter can be realized either by a microwave cavity or a nanomechanical resonator. Focusing on the subgap regime, we demonstrate that cross-Andreev reflection, through which Cooper pairs are split into both dots, can efficiently cool down each resonator into its ground state. Moreover, we show that a nonlocal heat transfer between the two resonators is activated when opportune resonance conditions are matched. The proposed scheme can act as a heat-pump device with potential applications in heat control and cooling of mesoscopic quantum resonators.

2019, Hussein, Robert, Governale, Michele, Kohler, Sigmund, Belzig, Wolfgang, Giazotto, Francesco, Braggio, Alessandro

We investigate the nonlocal thermoelectric transport in a Cooper-pair splitter based on a double-quantum-dot-superconductor three-terminal hybrid structure. We find that the nonlocal coupling between the superconductor and the quantum dots gives rise to nonlocal thermoelectric effects which originate from the nonlocal particle-hole breaking of the system. We show that Cooper-pair splitting induces the generation of a thermo-current in the superconducting lead without any transfer of charge between the two normal metal leads. Conversely, we show a nonlocal heat exchange between the normal leads mediated by non-local Andreev reflection. We discuss the influence of finite Coulomb interaction and study under which conditions nonlocal power generation becomes possible, and when the Cooper-pair splitter can be employed as a cooling device.