Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework

Singlet fission (SF) can generate an exchange-coupled quintet triplet pair
state 5TT, which could lead to the realization of quantum computing and
quantum sensing using entangled multiple qubits even at room temperature.
However, the observation of the quantum coherence of 5TT has been limited
to cryogenic temperatures, and the fundamental question is what kind of
material design will enable its room-temperature quantum coherence. Here
we show that the quantum coherence of SF-derived 5TT in a
chromophore-integrated metal-organic framework (MOF) can be over hundred
nanoseconds at room temperature. The subtle motion of the chromophores in
ordered domains within the MOF leads to the enough fluctuation of the
exchange interaction necessary for 5TT generation, but at the same time
does not cause severe 5TT decoherence. Furthermore, the phase and
amplitude of quantum beating can be controlled by molecular motion,
opening the way to room-temperature molecular quantum computing based on
multiple quantum gate control.