Coherent manipulation and quantum phase interference in a fullerene-based electron triplet molecular qutrit

High-spin magnetic molecules are promising candidates for quantum information processing because their intrinsic multiplicity facilitates information storage and computational operations. However, due to the absence of suitable sublevel splittings, their susceptibility to environmental disturbances and limitation from the selection rule, the arbitrary control of the quantum state of a molecular electron multiplet has not been realized. Here, we exploit the photoexcited triplet of C-70 as a molecular electron spin qutrit with pulsed electron paramagnetic resonance. We prepared the system into 3-level superposition states characteristic of a qutrit and validated them by the tomography of their density matrices. To further elucidate the coherence of the operation and the nature of the system as a qutrit, we demonstrated the quantum phase interference in the superposition. The interference pattern is further interpreted as a map of possible evolution paths in the space of phase factors, representing the quantum nature of the 3-level system.

Automated summary

High-spin magnetic molecules are potential candidates for quantum information processing due to their intrinsic multiplicity, but their quantum state control has been limited by environmental disturbances and selection rule constraints. By utilizing the photoexcited triplet of C-70 as a molecular electron spin qutrit, quantum phase interference and evolution paths in the space of phase factors were demonstrated, showcasing the quantum nature of the 3-level system.