Lin Liang-Chun, Smith Tanner, Ai Qianxiang, Rugg Brandon K, Risko Chad, Anthony John E, Damrauer Niels H, Johnson Justin C
Department of Chemistry, University of Colorado Boulder Boulder CO 80309 USA.
Department of Chemistry & Center for Applied Energy Research, University of Kentucky Lexington Kentucky 40506-0055 USA.
Chem Sci. 2023 Oct 2;14(41):11554-11565. doi: 10.1039/d3sc03153e. eCollection 2023 Oct 25.
The multiexciton quintet state, TT, generated as a singlet fission intermediate in pairs of molecular chromophores, is a promising candidate as a qubit or qudit in future quantum information science schemes. In this work, we synthesize a pyrene-bridged parallel tetracene dimer, TPT, with an optimized interchromophore coupling strength to prevent the dissociation of TT to two decorrelated triplet (T) states, which would contaminate the spin-state mixture. Long-lived and strongly spin-polarized pure TT state population is observed transient absorption spectroscopy and transient/pulsed electron paramagnetic resonance spectroscopy, and its lifetime is estimated to be >35 µs, with the dephasing time () for the TT-based qubit measured to be 726 ns at 10 K. Direct relaxation from TT to the ground state does diminish the overall excited state population, but the exclusive TT population at large enough persistent density for pulsed echo determination of spin coherence time is consistent with recent theoretical models that predict such behavior for strict parallel chromophore alignment and large exchange coupling.
在分子发色团对中作为单线态裂变中间体产生的多激子五重态TT，是未来量子信息科学方案中作为量子比特或量子位的有前途的候选者。在这项工作中，我们合成了一种芘桥连的平行并四苯二聚体TPT，其具有优化的发色团间耦合强度，以防止TT解离为两个不相关的三重态（T），这会污染自旋态混合物。通过瞬态吸收光谱和瞬态/脉冲电子顺磁共振光谱观察到了长寿命且强自旋极化的纯TT态布居，其寿命估计大于35 μs，在10 K下基于TT的量子比特的退相时间（）测量为726 ns。从TT直接弛豫到基态确实会减少整体激发态布居，但在足够大的持续密度下用于自旋相干时间脉冲回波测定的唯一TT布居与最近的理论模型一致，该模型预测了这种严格平行发色团排列和大交换耦合的行为。
