论文标题

用于量子近似优化的离子天然变异ansatz

Ion native variational ansatz for quantum approximate optimization

论文作者

Rabinovich, Daniil, Adhikary, Soumik, Campos, Ernesto, Akshay, Vishwanathan, Anikin, Evgeny, Sengupta, Richik, Lakhmanskaya, Olga, Lakhmanskiy, Kiril, Biamonte, Jacob

论文摘要

变分量子算法涉及使用经典协作者训练参数化的量子电路。量子近似优化算法是为组合优化设计的重要变分算法。在任何现代量子处理器上实现该算法都需要将问题实例嵌入到哈密顿量中,或者通过栅极序列模拟相应的传播器。对于大量的问题实例,由于当前的电路深度和硬件限制,这是不可能的。因此,我们适应了使用离子汉密尔顿人的变异方法来创建可以准备更普遍问题的汉密尔顿人的基础状态的Ansatze家庭。我们通过分析确定对称性保护的类,这些类别使某些问题实例无法访问,除非这些对称性被打破。我们详尽地搜索了六个量子位,并考虑了多达二十个电路层,表明可以打破对称性来解决Sherrington-Kirkpatrick Hamiltonian的所有问题实例。进一步,我们在数值上展示了培训收敛性和高度二十个量子位的水平改进。具体而言,这些发现扩大了基于离子的量子处理器可以解决的类问题实例。通常,这些结果是基于系统本地哈密顿量和对称性保护的量子近似优化方法的测试床。

Variational quantum algorithms involve training parameterized quantum circuits using a classical co-processor. An important variational algorithm, designed for combinatorial optimization, is the quantum approximate optimization algorithm. Realization of this algorithm on any modern quantum processor requires either embedding a problem instance into a Hamiltonian or emulating the corresponding propagator by a gate sequence. For a vast range of problem instances this is impossible due to current circuit depth and hardware limitations. Hence we adapt the variational approach -- using ion native Hamiltonians -- to create ansatze families that can prepare the ground states of more general problem Hamiltonians. We analytically determine symmetry protected classes that make certain problem instances inaccessible unless this symmetry is broken. We exhaustively search over six qubits and consider upto twenty circuit layers, demonstrating that symmetry can be broken to solve all problem instances of the Sherrington-Kirkpatrick Hamiltonian. Going further, we numerically demonstrate training convergence and level-wise improvement for up to twenty qubits. Specifically these findings widen the class problem instances which might be solved by ion based quantum processors. Generally these results serve as a test-bed for quantum approximate optimization approaches based on system native Hamiltonians and symmetry protection.

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