Qiu Yunfan, Eckvahl Hannah J, Equbal Asif, Krzyaniak Matthew D, Wasielewski Michael R
Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States.
J Am Chem Soc. 2023 Nov 29;145(47):25903-25909. doi: 10.1021/jacs.3c10772. Epub 2023 Nov 14.
An important criterion for quantum operations is long qubit coherence times. To elucidate the influence of molecular structure on the coherence times of molecular spin qubits and qudits, a series of molecules featuring perylenediimide (PDI) chromophores covalently linked to stable nitroxide radicals were synthesized and investigated by pulse electron paramagnetic resonance spectroscopy. Photoexcitation of PDI in these systems creates an excited quartet state () followed by a spin-polarized doublet ground state (), which hold promise as spin qudits and qubits, respectively. By tailoring the molecular structure of these spin qudit/qubit candidates by selective deuteration and eliminating intramolecular motion, coherence times of = 9.1 ± 0.3 and 4.2 ± 0.3 μs at 85 K for and , respectively, are achieved. These coherence times represent a nearly 3-fold enhancement compared to those of the initial molecular design. This approach offers a rational structural design protocol for effectively extending coherence times in molecular spin qudits/qubits.
量子操作的一个重要标准是长量子比特相干时间。为了阐明分子结构对分子自旋量子比特和量子位相干时间的影响，合成了一系列以共价连接到稳定氮氧自由基的苝二酰亚胺（PDI）发色团为特征的分子，并通过脉冲电子顺磁共振光谱进行了研究。这些体系中PDI的光激发产生一个激发四重态（），随后是一个自旋极化的二重态基态（），它们分别有望作为自旋量子位和量子比特。通过选择性氘化和消除分子内运动来定制这些自旋量子位/量子比特候选物的分子结构，在85 K时，和的相干时间分别达到= 9.1±0.3和4.2±0.3 μs。与最初的分子设计相比，这些相干时间提高了近3倍。这种方法为有效延长分子自旋量子位/量子比特的相干时间提供了一种合理的结构设计方案。
