8 research outputs found
Nonadiabatic Josephson current pumping by microwave irradiation
Irradiating a Josephson junction with microwaves can operate not only on the
amplitude but also on the phase of the Josephson current. This requires
breaking time inversion symmetry, which is achieved by introducing a phase
lapse between the microwave components acting on the two{\dag} sides of the
junction. General symmetry arguments and the solution of a specific single
level quantum dot model show that this induces chirality in the Cooper pair
dynamics, due to the topology of the Andreev bound state wavefunction. Another
essential condition is to break electron-hole symmetry within the junction. A
shift of the current-phase relation is obtained, which is controllable in sign
and amplitude with the microwave phase and an electrostatic gate, thus
producing a "chiral" Josephson transistor. The dot model is solved in the
infinite gap limit by Floquet theory and in the general case with Keldysh
nonequilibrium Green's functions. The chiral current is nonadiabatic: it is
extremal and changes sign close to resonant chiral transitions between the
Andreev bound states.Comment: 13 pages, 7 figures, extended versio
Material and integration challenges for large scale Si quantum computing
International audienceSi spin qubits are very promising to enable large scale quantum computing as they are fast, of high quality and small. However, they are still lagging behind in terms of number of qubits. Indeed there are material and integration challenges to be tackled before fully expressing their potential
Towards scalable quantum computing based on silicon spin
International audienc
Challenges and perspectives in the modeling of spin qubits
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