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Coherent coupling between a quantum dot and a donor in silicon

Vendredi 30 mars 14:00 - Duree : 1 heure
Lieu : Salle du bâtiment accueil, CEA - 17 rue des Martyrs - Grenoble

Orateur : Patrick HARVEY-COLLARD (Université de Sherbrooke and Sandia National Labs)

Individual donors and quantum dots in silicon chips are used as bits of quantum information with different but complementary advantages. In this work, we show that these two qubit systems can be combined by demonstrating the coherent interaction of a 31P donor electron with the electron of a metal-oxide-semiconductor quantum dot. We form a logical qubit encoded in the spin singlet and triplet states of the two-electron system. We show that the donor nuclear spin drives coherent rotations between the electronic qubit states through the contact hyperfine interaction. This provides every key element for compact two-electron spin qubits requiring only a single dot and no additional magnetic field gradients, as well as a means to interact with the nuclear spin qubit. This system furthermore introduces an engineered path to couple donors together, alleviating the need for challenging atomic-precision fabrication and providing a scalable path to multi-donor qubit systems. In this talk, I will also discuss our advances in engineering the valley splitting and the shell filling of QDs to overcome the system’s challenges. I will present a scheme for high fidelity spin readout that combines the advantages of the Pauli blockade and spin 1/2 readouts. If there is time, I will also discuss my recent work on spin-orbit interaction in silicon MOS devices. In this work, we use a silicon MOS double quantum dot singlet-triplet qubit as a sensitive probe of the spin-orbit effect. We first show that a strong magnetic field enables rotations between the singlet S and triplet T0, an effect which amounts to an effective g-factor difference between the two quantum dots. Two-axis control and single shot readout of the qubit is used to study AC resonant control and achieve few microsecond Rabi flip times. Secondly, we investigate a different effect of the spin-orbit interaction on the S/T− transition and its impact on schemes like dynamic nuclear polarization. Our results shed light on the implications of spin-orbit interaction for the operation of spin qubits in silicon. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE under contract DE-AC04-94AL85000.

Contact : marc.sanquer@cea.fr

Discipline évènement : (Physique)
Entité organisatrice : (INAC/SPSMS)
Nature évènement : (Séminaire)
Site de l'évènement : Site CEA sans badge requis

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