EAGER-QAC-QSA: Bifurcation-Enabled Efficient Preparation of Many-body Ground States

非技术概述该项目支持理论研究和教育，以实现具有实际设备的专用量子计算机。现在可以在实验室中建立具有50-100个量子比特和退相干时间不足以用于通用量子计算的量子计算机。有了这样的设备，量子模拟器，一种特殊用途的量子计算机，可能能够解决经典计算机无法解决的问题。实现量子模拟的前提是使模拟器处于适当的多体基态，这也有利于组合优化问题的解决。这些多体状态通常是未知的、高度纠缠的，很难用量子逻辑门来准备。尽管之前做出了努力，但准备如此高保真的多体国家仍然是一个具有挑战性的问题。PI旨在开发一种通用且可实现的算法，通过将量子模拟器耦合到诱导非线性的辅助系统来高效而准确地生成这种多体基态。这种新的方法利用非线性系统的一般但独特的性质来抑制基态和激发态之间不必要的转变。这个项目的目标包括开发算法的通用框架，对算法进行基准测试，以及研究电路噪声的影响。该算法将在代表量子模拟中不同兴趣问题的四个模型上进行测试。使用经典计算机的数值模拟和使用超导云平台的硬件仿真将被用来测试该算法。由于它利用了一般的非线性动力学，该算法可以应用于广泛的问题。该项目不仅对量子计算和量子模拟具有潜在的科学影响，而且还可以打开利用非线性物理进行高效量子计算的新方向的大门。该项目的教育部分将扩大妇女和少数族裔学生的参与，并提高量子技术劳动力的多样性。国际和平研究所将开发一门关于先进量子计算的课程，积极从代表性不足的群体中招收学生和博士后，并与加州大学默塞德分校的妇女STEM小组和物理学生学会一起组织活动。这些活动将使西班牙裔服务机构加州大学默塞德分校的学生参与量子研究。技术总结这个项目支持关于使用嘈杂的中型量子设备实现量子模拟的理论研究和教育。量子模拟器是一种特殊用途的量子计算机，可以解决经典难题。多体系统基态的有效制备是在量子模拟器中探索量子动力学和多体关联的前提。了解态制备的可行性和局限性也有助于绝热量子计算中组合优化问题的研究。尽管前人做了大量的工作，但由于缺乏对能谱的了解、能隙随量子模拟器的大小迅速减小以及实际器件中有限的退相干时间，制备高保真的多体态仍然是一个具有挑战性的问题。PI旨在开发一种通用且可实现的算法，通过将量子模拟器耦合到诱导非线性的辅助系统来高效而准确地生成多体基态。这种新的方法利用了分叉点附近的独特动力学特性，这是非线性系统中的一个普遍特性，使得能够在显著抑制非绝热跃迁的情况下实现自主绝热演化。该项目包括三个目标：1.制定算法的通用框架、操作协议和对量子电路的要求；2.对算法进行基准测试并将其性能与其他方法进行比较；3.定性地研究电路噪声的影响。该算法将在代表量子模拟中不同兴趣的四个模型上进行测试：横场伊辛模型、精确覆盖问题、有限大小的Jaynes-Cummings格子和具有多个能隙的玩具模型。在IBM Q云平台上进行了数值模拟和硬件仿真，验证了算法的有效性。由于它利用了一般的非线性动力学，该算法可以在不知道能谱或构造非物理多体相互作用的情况下应用于广泛的问题。该项目不仅对量子计算和量子模拟具有潜在的科学影响，而且还可以打开利用非线性物理进行高效量子计算的新方向的大门。该项目的教育部分将扩大妇女和少数族裔学生的参与，并提高量子技术劳动力的多样性。国际和平研究所将开发一门关于先进量子计算的课程，积极从代表性不足的群体中招收学生和博士后，并与加州大学默塞德分校的女性STEM小组和物理学生学会一起组织活动。这些活动将吸引加州大学默塞德分校的学生参与量子研究。该奖项反映了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。

Nontechnical SummaryThis project supports theoretical research and education on the implementation of a special purpose quantum computer with practical devices.Quantum computers with 50-100 qubits and decoherence times not long enough for general-purpose quantum computing can now be built in laboratories. With such devices, a quantum simulator, a special-purpose quantum computer, may be able to solve problems that cannot be solved with classical computers. A prerequisite to implementing quantum simulation is to prepare the simulator in an appropriate many-body ground state, something that could also benefit the solution of combinatorial optimization problems. These many-body states are often unknown, highly entangled, and hard to prepare with quantum logic gates. Despite previous efforts, it remains a challenging question to prepare such many-body states with high fidelity. The PI aims to develop a universal and implementable algorithm to efficiently and accurately generate such many-body ground states by coupling the quantum simulator to an auxiliary system that induces nonlinearity. This novel approach exploits a generic but unique property of nonlinear systems to suppress unwanted transitions between the ground state and the excited states. The objectives of this project include the development of the general framework for the algorithm, benchmarking the algorithm, and studying the effect of circuit noise. The algorithm will be tested on four models that represent problems of different interests in quantum simulation. Both numerical simulation using classical computers and hardware emulation using a superconducting cloud platform will be employed to test the algorithm. Because it exploits generic nonlinear dynamics, this algorithm can be applied to a broad range of problems.The project not only has potential scientific impact on quantum computing and quantum simulation, but it can also open the door to a new direction that uses nonlinear physics for efficient quantum computing. The educational component of this project will broaden the participation of women and minority students and improve the diversity of the workforce in quantum technology. The PI will develop a course on advanced quantum computing, actively recruit students and postdocs from underrepresented groups, and organize activities with the women-in-STEM group and the Society of Physics Students at UC Merced. These activities will engage students at UC Merced, a Hispanic serving institute, in quantum research.Technical SummaryThis project supports theoretical research and education on the implementation of quantum simulation with noisy intermediate-scale quantum devices.A quantum simulator is a special-purpose quantum computer that can solve classically-hard problems. Efficient preparation of a many-body system in its ground state is a prerequisite for exploring quantum dynamics and many-body correlations in quantum simulators. Understanding the feasibility and limits on state preparation also benefits the study of combinatorial optimization problems in adiabatic quantum computing. Despite previous efforts, it remains a challenging question to prepare many-body states with high fidelity due to the lack of knowledge of the energy spectrum, the rapid decrease of energy gaps with the size of the quantum simulator, and the limited decoherence times in practical devices. The PI aims to develop a universal and implementable algorithm to efficiently and accurately generate many-body ground states by coupling a quantum simulator to an auxiliary system that induces nonlinearity. This novel approach exploits the unique dynamics in the vicinity of bifurcation points, which is a generic property in nonlinear systems, to enable self-governed adiabatic evolution with significantly suppressed diabatic transitions. The project includes three objectives: 1. developing the generic framework, operational protocol, and requirements on the quantum circuits for the algorithm, 2. benchmarking the algorithm and comparing its performance with other methods, and 3. qualitatively studying the effect of circuit noise. The algorithm will be tested on four models representing different interests in quantum simulation: the transverse-field Ising model, an exact-cover problem, a finite-sized Jaynes-Cummings lattice, and toy models with multiple energy gaps. Both numerical simulation and hardware emulation using the IBM Q cloud platform will be employed to test the algorithm. Because it exploits generic nonlinear dynamics, this algorithm can be applied to a broad range of problems without knowledge of the energy spectrum or the construction of unphysical multipartite interactions.The project not only has potential scientific impact on quantum computing and quantum simulation, but it can also open the door to a new direction that uses nonlinear physics for efficient quantum computing. The educational component of this project will broaden the participation of women and minority students and improve the diversity of the workforce in quantum technology. The PI will develop a course on advanced quantum computing, actively recruit students and postdocs from underrepresented groups, and organize activities with the women-STEM group and the Society of Physics Students at UC Merced. These activities will engage students at UC Merced, a Hispanic serving institute, in quantum research.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.