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

Project description

Controlling and reading out molecular spins for scalable quantum computing

Conventional computers represent, process and store information as combinations of zeros and ones. Transistors are the physical method of storage of these 'bits' of information since transistors are like switches with an 'on' or 'off' state. Qubits, or quantum bits, rely on quantum states of a 2-level quantum system. Spins in molecules have discrete energy levels, and their associated quantum states can be used to encode qubits. Further, molecules are larger and more versatile than atoms, opening the door to scalability. We need the ability for control and readout on fast time scales. The EU-funded cQMM project will tackle this challenging task with the help of nanomechanical resonators.


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.



Net EU contribution
€ 157 184,72
Rue michel ange 3
75794 Paris

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Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
Other funding
€ 39 523,12