Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture
Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture
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DOI：
10.1038/s41534-017-0022-6
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发表时间：
2017-06-09
影响因子：
7.6
通讯作者：
Warburton, P. A.
中科院分区：
文献类型：
--
作者：
Chancellor, N.;Zohren, S.;Warburton, P. A.
量子退火提供了一种解决优化问题的方法，将它们编码为使用物理量子位实现的伊辛自旋模型。然后，优化问题的解对应于系统的基态。利用量子隧穿使系统能够在潜在的高非凸能量景观中移动到基态。在物理量子退火设备中编码优化问题的主要困难在于，许多真实的世界优化问题需要更高连通性的相互作用，以及超出物理硬件限制的多体项。在这项工作中，我们解决的问题，如何实现多体相互作用，使用硬件本身只提供两个机构的相互作用。主要结果是使用超导通量量子比特的这种多体项的有效电路设计，其中使用N个辅助量子比特和仅两个电感耦合器来实现有效的N体相互作用。然后，它示出了如何将该电路可以被用作一个可扩展的架构的单元格，通过将其应用到最近提出的嵌入技术，用于构建具有任意连接的逻辑量子位的架构，使用具有最近邻居四体相互作用的物理量子位。它进一步表明，这种设计是强大的耦合回路中的非线性效应，以及在一些电路参数的失配。
Quantum annealing provides a way of solving optimization problems by encoding them as Ising spin models which are implemented using physical qubits. The solution of the optimization problem then corresponds to the ground state of the system. Quantum tunneling is harnessed to enable the system to move to the ground state in a potentially high non-convex energy landscape. A major difficulty in encoding optimization problems in physical quantum annealing devices is the fact that many real world optimization problems require interactions of higher connectivity, as well as multi-body terms beyond the limitations of the physical hardware. In this work we address the question of how to implement multi-body interactions using hardware which natively only provides two-body interactions. The main result is an efficient circuit design of such multi-body terms using superconducting flux qubits in which effective N-body interactions are implemented using N ancilla qubits and only two inductive couplers. It is then shown how this circuit can be used as the unit cell of a scalable architecture by applying it to a recently proposed embedding technique for constructing an architecture of logical qubits with arbitrary connectivity using physical qubits which have nearest-neighbor four-body interactions. It is further shown that this design is robust to non-linear effects in the coupling loops, as well as mismatches in some of the circuit parameters.