Spin-controlled stimulated echo formed in molecular triads through photodriven quantum teleportation.

A new protocol for recording correlations in the spin system preserved during photodriven quantum teleportation in molecular triads is proposed. It is assumed that an electron can be transferred from donor (D) to acceptor (A) by photoexcitation and that reduction of the stable radical (R) by the acceptor radical anion can take place. The protocol is based on the three-pulse stimulated spin echo sequence, with the first and third microwave pulses selectively applied to the spin R and the second microwave pulse applied to the spin D. Only those molecules in which the state of spin R is teleported to spin D contribute to the spin echo. The echo is formed only when the spin state of radical R after the first microwave pulse is dephased, transferred to the state of D by the laser flash and conserved by the second microwave pulse, and reversed to the state of radical R by charge recombination and refocused after the third pulse. The proposed procedure allows the state in which the radical is reduced to be studied even when its lifetime is short compared to the spin evolution. It also might be useful for investigating the validity of the Haberkorn approach to determining the spin decoherence rate induced by the recombination of the radical pairs. Possible perspectives on the preservation of the correlation between the electron and the nuclear spins in the context of quantum phenomena in spin chemistry research are discussed.