SPICE Workshop on Quantum Functionalities of Nanomagnets, June 17th - 19th 2025
Matthieu Delbecq
Electron spins in quantum dots represent an attractive path towards the realization of quantum processors due to the high spin resilience to environmental noise and the large electric dipole allowed by the DQD. While multi-qubit gates are commonly mediated through nearest-neighbor exchange interaction, achieving coherent long-range coupling between spins remains a major challenge for such architectures. Enabling spin-photon interaction is thus appealing. In this talk I will discuss recent progress we made in this field with carbon nanotube based devices in circuit quantum electrodynamics architecture (cQED).
We manipulated the quantum state of an ultra-clean suspended carbon nanotube double quantum dot with ferromagnetic contacts embedded in a microwave cavity. By performing quantum manipulations in the time domain via the cavity photons, we demonstrated coherence times T2* of the order of 1.3 microseconds. This is two orders of magnitude larger than what was ever measured in any carbon quantum circuit and one order of magnitude larger than silicon based quantum dots in comparable environment, finally showing the potential of carbon nanotube as a good host material for spin qubits.