  High spin magnetic molecules are promising candidates for quantum information
processing because they intrinsically have multiple sublevels for information
storage and computational operations. However, due to their susceptibility to
the environment and limitation from the selection rule, the arbitrary control
of the quantum state of a multilevel system on a molecular and electron spin
basis has not been realized. Here we exploit the photoexcited triplet of C70 as
a molecular electron spin qutrit. After the system was initialized by
photoexcitation, we prepared it into representative three-level superposition
states characteristic of the qutrit, measured their density matrices, and
showed the interference of the quantum phases in the superposition. The
interference pattern is further interpreted as a map of evolution through time
under different conditions.
