Nonadiabatic Transition Probabilities: Applications in Spectroscopy, Quantum Thermodynamics, and Quantum Computing

在化学系化学理论、模型和计算方法项目的支持下，密歇根州立大学的凯瑟琳·亨特正在开发新的量子力学理论和计算分析，以确定由外部电磁场引起的分子状态的变化。 亨特和她的研究小组将分析一个与时间相关的电磁场诱导从分子的初始量子态到激发态的跃迁的概率。 研究结果有望在分析能量吸收和能量转换器件方面有重要的应用。 量子奥托发动机的功、热、功率和效率将在亨特研究小组开发的新理论中进行分析。 这项分析预计将表明，量子发动机可以超过传统的卡诺限制，将热量转化为有用功。 该分析还可能提出改善量子制冷机性能的方法，这是由于减少电子元件尺寸和相关散热问题的推动而需要的。 对该理论的新测试将由亨特研究小组与实验研究小组合作进行。 该理论将应用于量子计算的背景下，提出新的算法，可以最大限度地减少错误和探测量子纠缠的影响。 除了上述在工程和计算机科学方面的潜在广泛影响外，该项目还将通过将本科生和高中生纳入研究团队以及编写教学文章，在将STEM（科学、技术、工程和数学）研究与教育相结合方面产生更广泛的影响。 在整个项目中，将鼓励妇女、残疾人和代表性不足的少数群体的充分参与。亨特小组探索了一种超越狄拉克跃迁理论的理论，将量子系统的实际激发与对扰动的绝热响应分开。 该小组将开发方法，充分考虑退相干和激发态的衰变，导致预测的激发态的占用预计将不同于狄拉克理论，扰动结束后。 多芳香族化合物的振动光谱、小分子的超快光谱和较大分子的非绝热电子跃迁将用作测试案例。 此外，通过斯塔克诱导绝热拉曼通道在选定的激发振转态的分子的生产将被调查，与非零相位阻尼添加到现有的理论的潜在影响。 当应用于量子奥托发动机的操作时，已知亨特群理论在动力冲程结束时产生与先前理论的量子态占据率的差异;预计它将预测整体发动机效率的差异，超过卡诺极限。 本文将研究一种新的绝热量子计算算法，该算法基于非绝热和绝热响应的逐步分离，以减少误差。 这项工作预计将在工程和计算机科学领域产生更广泛的影响，通过应用于有限时间量子运算，能量吸收和转换设备，量子发动机，量子冰箱和量子计算。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Katharine Hunt of Michigan State University is developing new quantum mechanical theory and computational analyses to determine the changes in molecular states caused by external electromagnetic fields. Hunt and her research group will analyze the probability for a time-dependent electromagnetic field to induce transitions from the initial quantum state of a molecule to excited states. The results are expected to have important applications in analyzing energy uptake and energy conversion devices. The work, heat, power, and efficiency of quantum Otto engines will be analyzed within the new theory developed by the Hunt research group. This analysis is expected to show that quantum engines can exceed traditional Carnot limits on the conversion of heat into useful work. The analysis may also suggest means of improving the performance of quantum refrigerators, which are needed due to the push to reduce the size of electronic components and the associated problems of heat dissipation. Novel tests of the theory will be carried out in collaborations by the Hunt research group with experimental research groups. The theory will be applied in the context of quantum computing, to suggest new algorithms that may minimize error and to probe effects of quantum entanglement. In addition to the potential broader impacts in engineering and computer science mentioned above, the project will have broader impact in integrating STEM (science, technology, engineering and mathematics) research with education, through the inclusion of undergraduates and high school students in the research team and the preparation of pedagogical articles. The full participation of women, persons with disabilities, and underrepresented minorities will be encouraged throughout the project.The Hunt group has explored a theory that goes beyond Dirac’s theory of transitions, to separate the actual excitations of quantum systems from the adiabatic response to a perturbation. The group will develop methods to take full account of decoherence and decay of excited states, leading to predictions for the occupancy of excited states that are expected to differ from Dirac theory, after a perturbation has ended. Vibrational spectroscopy of polyaromatic compounds, ultrafast spectroscopy of small molecules, and nonadiabatic electronic transitions in larger molecules will be used as test cases. In addition, the production of molecules in selected excited rovibrational states via Stark-induced adiabatic Raman passage will be investigated, with the potential effects of non-zero phase damping added to the existing theory. As applied to the operation of quantum Otto engines, the Hunt-group theory is known to produce differences from previous theories in the quantum-state occupancies at the end of the power stroke; it is expected to predict differences in the overall engine efficiency, surpassing the Carnot limits. A new algorithm for adiabatic quantum computing will be investigated, based on step-wise separation of nonadiabatic and adiabatic response, to reduce errors. The work is expected to have broader impact in engineering and computer science, through applications to finite-time quantum operations, energy uptake and conversion devices, quantum engines, quantum refrigerators, and quantum computing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.