All electronics “runs on quantum mechanics”, from semiconductors and lasers to giant-magnetoresistance-based hard drives and memories. A number of technologies even depend very explicitly of quantum effects, from medical MRIs to quantum dots. Nevertheless, there is ample room for research, development and innovation in the next-generation quantum technologies such as quantum computation, quantum key distribution and quantum metrology, which all revolve around the coherent manipulation of the wave function and the concept of quantum two-state system or qubit. Very different physical, chemical or even biological systems can embody a qubit, but not all are equally well suited. For decades, a large number of physicists –including giants such as Haroche and Cirac– have performed experiments on trapped ions and resonant cavities, performing quantum manipulations that often were beyond the capabilities of quantum dots or SQUIDs. However, in recent times the spectacular results using Nitrogen-Vacancy (NV) defects in a diamond matrix have shown the potential of systems in the domain of Chemistry and Materials Science. In the last few years, the study of quantum effects in a chemical context is also becoming a hot topic for biophysicists. Whatever the hardware, the key to quantum technologies are basic quantum effects: quantum superposition and quantum correlations. In real systems, and specially in the solid state, these quantum states are very fragile: uncontrolled interaction with the environment destroy, they lose any existing quantum superposition and/or quantum correlations. This phenomenon, called decoherence, is a major obstacle for quantum aplications. As a result, it will not be possible to exploit the advantages of solid state systems, such as stable circuits or scalability, that would make them disruptive technologies, until we have a realistic model for decoherence. Of course, to give practical answers we will need to choose and focus on a particular qubit architecture. In our case we will focus on molecular spin qubits, as this molecular approach appears to be very promising to chemically design and manipulate spins in solid matter. A major advantage of molecular spin qubits over other candidates stems from the power of chemistry for a tailored and inexpensive synthesis of systems for their experimental study. Molecular Magnetism has produced an array of tools to study, design and fine-tune magnetic molecules, and, in particular, Single-Molecule Magnets (SMMs). Experimentally, magnetic molecules have already been used to perform experiments on coherent oscillations, and there have been recent theoretical studies about coherently manipulating a single qubit with electric fields. Note that Quantum Tunneling of the Magnetization, which can be seen as a particular case of decoherence, is the main phenomenon in SMMs. Moreover, SMMs typically have a doubly (near-)degenerate ground state with a large separation to the first excited state, that is, a qubit, and a crucial parameter to describe this qubit is the tunneling splitting breaking its near degeneracy. Thus, SMMs have a potential to be crucial in understanding and solving the decoherence problem for the Solid State, much like in the first days of Quantum Computing, NMR was key to implement the first quantum circuits. The general goal of this project will be to model decoherence in molecular spin systems of various nuclearities based on lanthanoid complexes.
