Vibrational State Approach to Quantum Computing

提出了一种有前途的量子计算新方法的理论研究，该方法使用分子的振动本征态来表示量子比特，并使用最优控制形成的快速飞秒红外激光脉冲来应用量子逻辑门（即诱导特定的振动跃迁）。这种方法可能满足量子计算的所有五个DiVincenzo标准，并提供了在亚皮秒时间尺度上运行的独特可能性。目前的实验技术使用反馈回路来优化脉冲形状。然而，在没有理论指导的情况下，实验人员面临着巨大的参数空间，需要在其中寻找最优的脉冲参数。如果不仔细选择脉冲参数，实验脉冲形状优化过程可能不会收敛，或者可能引起非常不希望的过渡。本研究的目的是为形状脉冲的各种参数（持续时间、频谱、幅度等）的选择提供重要的理论指导。此外，最适合量子逻辑运算的特定分子是未知的，理论计算将有助于选择实验考虑的最佳候选分子。提案中提出的初步结果证明了理论研究对该领域进一步发展的重要性，支持了方法的可行性，并证明了作者进行拟议研究的能力。

A theoretical study is proposed of a promising new approach to quantum computing which uses the vibrational eigenstates of molecules to represent quantum bits, and fast femtosecond infrared laser pulses shaped with optimal control to apply quantum logic gates (i.e., to induce specific vibrational transitions). This approach potentially meets all five DiVincenzo criteria for quantum computing and offers the unique possibility of operation on a sub-picosecond time scale. Current experimental techniques use feedback loops to optimize the pulse shape. However, without theoretical guidance, experimentalists are faced with an over-whelmingly large parameter space in which to search for optimal pulse parameters. If pulse parameters are not carefully chosen, the experimental pulse shape optimization procedure may not converge, or it may induce highly undesirable transitions. The objective of this study is to provide crucial theoretical guidance for choosing the various parameters (duration, frequency spectrum, amplitude, etc.) of the shaped pulses. Furthermore, specific molecules which are best for quantum logic operations are unknown and theoretical calculations will help to choose the best candidates for experimental consideration. Preliminary results presented in the proposal demonstrate importance of theoretical studies for further progress in the field, support feasibility of the approach and attest to the ability of the author to conduct the proposed research.