cQMM · circuit Quantum Magneto-Mechanics : interfacing single molecular spins with nanomechanical resonators in the quantum regime.

The spin degree of freedom is a natural candidate to carry quantum information. Because of a generally weak coupling to its environment, it benefits from long lifetimes even in solid-state devices. The counterpart of this natural isolation is the challenge to engineer efficient control and readout of these spin states. Even more challenging is the coupling between distant spins, which is fundamental requirement to perform quantum computations. Among the various types of existing spin systems, molecular spins have shown remarkable properties. They are stable, they can be produced in large numbers of absolutely identical molecules and their properties are tuned and defined via chemical synthesis. The host group is recognized as an international leader in the field of molecular spins and has recently demonstrated elementary quantum information processing with such spins.Besides, it is known that in a solid state context, the dominant source of decay for molecular spins comes from the coupling to their mechanical environment via spin-phonon coupling. These phonons are often seen as a nuisance, but they actually constitute an interesting degree of freedom that has recently been intensely investigated in the field of circuit quantum electromechanics. The ER has acquired experience in this field during his 3.5 years of postdoc in the group of Konrad Lehnert (USA), a pioneering group in this field. We propose to take advantage of the natural spin-phonon coupling in molecular magnets, maximize it, and use it as a resource to control and readout molecular spins on fast time scales. The architecture consists of a molecular spin deposited on a mechanical oscillator in the quantum regime, which is controlled using the powerful techniques available in circuit quantum electromechanics. Such an interface could enable the coupling of distant molecular spins, but also the coupling to other degree of freedom such as optical photons, superconducting qubits or other spin systems.