WG3. Molecular spins for quantum technologies
Quantum technologies appears as a promising area in which magnetic molecules can be used not only for the storage of classical bits, but also for the creation, manipulation and readout of quantum superpositions of two spin states, thus providing realizations of spin qubits. The possible advantages of molecular spin systems in this context are the long quantum-coherence times they exhibit compared with semiconducting materials and the possibility of scalability either by arranging several qubits in a given molecule or by self-assembly processes. While coherent manipulation of single molecular qubits has been already demonstrated as well as spin entanglement at supramolecular level, effort is now concentrated on multi (two) qubit gates and on hybrid devices comprising molecular spins.
One of the issues to be addressed in this area is that of increasing the coherence time of the magnetic molecules. Application of error correction protocols imposes that gate operations must be 10^4 times faster than the rate at which qubits lose coherence (at present this figure of merit stands at 10^3). The couplings of the spins with the environment (phonons, nuclear spins, dipolar interactions) are important sources of decoherence, which are far from being understood and controlled. Still, via an appropriate chemical design of the molecule, some sources of decoherence (nuclear hyperfine and dipolar interactions) can be minimized. Furthermore, pulsed EPR experiments need to be performed in order to measure the decoherence parameters, together with theoretical calculations to account for the different mechanisms of decoherence.
A second important issue to be addressed is the search for new spin qubits architectures and the schemes for applying quantum information processing tasks. In this context the quantum behaviour of magnetic molecules is unique for the richness and variety of levels and states, and also for the wide possibilities to couple spins between them (entanglement), or with the external world (photons, electrons, nuclei, phonons). This issue involves strong theoretical and experimental efforts.
This WG will have strong interactions with WG2.
The associated research tasks to reach these goals can be summarized as follows:
T3.1. Chemical design of molecular spin qubits and qu-gates.
T3.2. Experimental and theoretical studies of the quantum coherence processes.
T3.3. Search for new spin qubits architectures and fabrication of quantum devices.
The key milestones are:
M3.1. Demonstration that magnetic molecules can be used for encoding multi-qubit gates.
M3.2. Definition of reliable procedures for preparing, characterising and positioning organized arrays of molecular spin qubits. Development of models and experimental setups for efficient coherent control and read-out.
M3.3. Realization of hybrid quantum devices including molecular spin.
Working Group 3
Leader: Fernando Luis