Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 46: Quantum Dots, Quantum Wires, Point Contacts

TT 46.2: Vortrag

Mittwoch, 3. April 2019, 15:15–15:30, H22

Enhancing entanglement by spin manipulation in Cooper pair splitters — •Ciprian Padurariu1, Jami Rönkkö2, Michael V. Moskalets3, and Christian Flindt21Institute for Complex Quantum Systems and IQST, Ulm University, 89069 Ulm, Germany — 2Department of Applied Physics, Aalto University, 00076 Aalto, Finland — 3Department of Metal and Semiconductor Physics, NTU Kharkiv Polytechnic Institute, 61002 Kharkiv, Ukraine

We study a Cooper pair splitter device consisting of two single level quantum dots fabricated in a strong spin-orbit coupling material (such as InAs or InSb) and coupled to a superconductor. The combined presence of spin-orbit coupling and Zeeman field gives rise to a finite probability of Cooper pair tunneling accompanied by spin flip, thereby involving the spin-triplet states of the doubly occupied dots.

We show that the population of triplet states leads to the spin blockade of Cooper pair tunneling. The blockade is advantageous for entanglement production if Cooper pair tunneling is resonant, when the blockaded electrons are in a fully entangled spin state. The entangled state is a superposition of singlet and triplet Bell states.

We propose two detection schemes, the first based on conventional transport spectroscopy and a second, based on charge detectors, [1] suitable for future devices capable of producing on-demand spin-entangled pairs.
N. Walldorf, C. Padurariu, A.-P. Jauho, and C. Flindt, Phys. Rev. Lett. 120, 087701 (2018).

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