Quantum interference of tunnel trajectories between states of different spin length in a dimeric mol

Abstract

An experimental study of a ‘dimeric’ single-molecule magnet—consisting of two coupled half-wheels of spin 7/2 each—provides evidence for quantum interference between the two sub-systems. Tunable electron spins in solid media are among the most promising candidates for qubits1. In this context, molecular nanomagnets have been proposed as hardware for quantum computation2. The flexibility in their synthesis represents a distinct advantage over other spin systems, enabling the systematic production of samples with desirable properties, for example, with a view to implementing quantum logic gates3,4. Here, we report the observation of quantum interference associated with tunnelling trajectories between states of different total spin length in a dimeric molecular nanomagnet. We argue that the interference is a consequence of the unique characteristics of a molecular Mn12 wheel, which behaves as a molecular dimer with weak ferromagnetic exchange coupling: each half of the molecule acts as a single-molecule magnet, whereas the weak coupling between the two halves gives rise to an extra internal spin degree of freedom within the molecule—that is, its total spin may fluctuate. More importantly, the observation of quantum interference provides clear evidence for quantum-mechanical superpositions involving entangled states shared between both halves of the wheel.

Cite this article

Ramsey, C., del Barco, E., Hill, S. et al. Quantum interference of tunnel trajectories between states of different spin length in a dimeric molecular nanomagnet. Nature Phys 4, 277–281 (2008). https://doi.org/10.1038/nphys886

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