EAGER: Chemically-Inspired, Tunable Quantum Computing Architectures for Dynamics of Molecular Systems

在化学系化学理论、模型和计算方法计划的支持下，印第安纳大学的菲利普·里切姆和斯里尼瓦桑·艾扬格正在开发受量子化学动力学启发并用于研究量子化学动力学的量子设备。Richerme和Iyengar研究的化学过程在大多数生物、材料和大气系统的反应化学中起着核心作用。例如，量子化学动力学可能是具有全球重要性的催化转化的基础，包括二氧化碳的减少，这对将温室气体转化为有用的原料、人工光合作用和固氮至关重要。对这些过程进行建模的经典方法一直不成功，因为它们需要指数级的大量计算资源来准确描述系统中大量的量子力学电子和原子核。相反，Richerme和Iyengar将使用基本的量子硬件，其设计反映了正在研究的分子的几何形状，以模拟这些化学系统的动力学。这可能使他们能够直接计算这些系统的波包动力学和振动光谱，而不需要大量的门模型量子计算开销。此外，该项目将为实验和理论研究生提供丰富的培训环境-包括MS和博士水平-并将在印第安纳大学量子硕士学位计划内开发量子化学轨道，满足全国公认的量子信息科学领域劳动力发展的需求。Richerme和Iyengar将开发一种新方法，将化学系统的微观量子相互作用映射到工程量子硬件。他们的核心见解是，量子物体的相对几何形状决定了它们的连接性，从而决定了它们的行为，并在设计量子硬件以模拟自然过程时提供了显著的简化。他们从分子本身的几何结构中获得灵感，安排了囚禁离子量子比特阵列的几何结构，以自然地复制不同核自由度之间的相互作用和纠缠传播的时间尺度。这种方法的动机是观察到紧密间隔的囚禁离子量子比特相互作用强烈，而相互作用随着离子-离子距离的增加而迅速衰减。这种从相对离子位置产生的耦合强度的差异提供了一个框架，在这个框架中，在多个密集分布的离子群内并行模拟多个核维度；然后，跨这些离子团的弱耦合产生有效核自由度之间的关联。通过改变施加到离子陷阱电极上的限制电压，离子团簇之间的间距可以控制到亚微米精度，这类似于以前的工作，即控制陷阱电压以实现等间距的离子串。一旦这些自然相互作用通过系统几何被编码，模拟量子模拟方法应该能够在系统中传播分子动力学和提取振动频率，而不需要指数数量的量子门。这种方法的成功有可能在量子动力学和振动光谱领域带来变革。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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, Philip Richerme and Srinivasan Iyengar of Indiana University, are developing quantum devices inspired by and for the study of quantum chemical dynamics. The chemical processes studied by Richerme and Iyengar play central roles in the reactive chemistry of most biological, materials, and atmospheric systems. For instance, quantum chemical dynamics likely underlie catalytic transformations of global importance, including the reduction of CO2, which is critical to converting this greenhouse gas to useful feedstocks, artificial photosynthesis, and nitrogen fixation. Classical approaches toward modeling these processes have been unsuccessful, since they would require exponentially large computing resources to accurately describe the large numbers of quantum-mechanical electrons and nuclei within the system. Instead, Richerme and Iyengar will use fundamentally quantum hardware, whose design mirrors the geometry of the molecules under study, to emulate the dynamics of these chemical systems. This may allow them to directly calculate wavepacket dynamics and vibrational spectra for these systems without the significant overhead of gate-model quantum computation. In addition, this project will provide a rich training environment for experimental and theory graduate students – both at the MS and PhD levels – and will enable the development of a Quantum Chemistry track within the Indiana University Quantum Master’s degree program, addressing the nationally-recognized need for workforce development in the area of Quantum Information Science.Richerme and Iyengar will develop a new approach to mapping the microscopic quantum interactions of chemical systems to engineered quantum hardware. Their central insight is that the relative geometry of quantum objects drives their connectivity, and hence, behavior and offers significant simplifications when designing quantum hardware to emulate natural processes. Drawing inspiration from the geometry of the molecules themselves, they arrange the geometry of trapped-ion qubit arrays to natively replicate the interactions and timescales of entanglement propagation between the various nuclear degrees of freedom. This approach is motivated by the observation that closely-spaced trapped-ion qubits interact strongly, while interactions decay quickly as the ion-ion distance is increased. This difference in coupling strengths, emerging from the relative ion positions, provides a framework in which multiple nuclear dimensions are simulated in parallel within multiple closely-spaced groups of ions; weak couplings across these ion clusters then generates correlations among the effective nuclear degrees of freedom. The spacing between ion clusters is controllable to sub-micron precision by changing the confinement voltages applied to ion-trap electrodes, similar to prior work which controls the trap voltages to achieve equally-spaced ion strings. Once these native interactions are encoded through the system geometry, analog quantum simulation methods should enable propagation of the molecular dynamics and extraction of the vibrational frequencies in the system, without requiring exponential numbers of quantum gates. Success in this approach has the potential to be transformational in the fields of quantum dynamics and vibrational spectroscopy.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.