Presentation of the project

While spins are excellent quantum bits, their long-range coupling remains a challenge to tackle towards complex quantum computing architectures. Our research proposes to take up this challenge using a microwave photon as a quantum mediator between qubits in silicon (see first figure).

Practically, we plan to couple hole spin-orbit qubits in silicon to high impedance microwave resonators as illustrated in second figure. We expect that a strong photon/spin-orbit qubit is achievable allowing long distance quantum state transfer between spin qubits.

This project involves Romain Maurand, Cécile Yu, Gonzalo Troncoso Fernandez-Bada, Estelle Vincent, Simon Zihlmann, Zoltan Scherubl, Frederic Gustavo, Jean-luc Thomassin et Frederic Poletti. It is funded by the European Research council under the ERC starting grant project LONGPSIN (link).

Scientific Publication about "CQED with spins project :

Strong coupling between a photon and a hole spin in silicon

We demonstrate strong coupling between a microwave photon in a superconducting resonator and a hole spin in a silicon-based double quantum dot issued from a foundry-compatible metal–oxide–semiconductor fabrication process. By leveraging the strong spin–orbit interaction intrinsically present in the valence band of silicon, we achieve a spin–photon coupling rate as high as 330 MHz, largely exceeding the combined spin–photon decoherence rate. This result, together with the recently demonstrated long coherence of hole spins in silicon, opens a new realistic pathway to the development of circuit quantum electrodynamics with spins in semiconductor quantum dots.

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Magnetic field resilient high kinetic inductance superconducting niobium nitride coplanar waveguide resonators

High quality superconducting microwave resonators are at the heart of circuit quantum electrodynamics experiments. Here, we report on simple to fabricate coplanar waveguide resonators fabricated from a thin film of NbN. Using the large kinetic inductance of NbN, we achieve characteristic impedances of up to 4 kOhm. These large impedances, paired with the excellent magnetic field resilience (see figure), makes these resonators perfectly suited for cQED experiments requiring magnetic fields such as spin qubits.

Read more in Yu et al. APL 118 054001 (2021)