论文标题
经典$ \ mathbb {z} _2 $旋转液体在可编程量子设备中的实验实现
Experimental Realization of Classical $\mathbb{Z}_2$ Spin Liquids in a Programmable Quantum Device
论文作者
论文摘要
我们在可编程量子设备（D-Wave DW-2000Q）中构建和探测$ \ mathbb {z} _2 $旋转液体。具体而言，我们观察到经典的8 vertex和6 vertex（自旋冰）及其之间的过渡。为了实现这种物质状态，我们仅使用成对的量相互作用和横向场，即在此量子设备中可访问的相互作用，设计一种使用组合量规对称性的哈密顿量。组合规量规的对称性保持沿着完整的量子退火路径保持精确，将系统降落到路径端点的经典8-Vertex模型上。设备的输出配置使我们能够直接观察经典模型的循环结构。此外，我们变形了哈密顿量，以改变8个顶点的权重，并表明我们可以选择性地达到经典的6-Vertex（ICE）模型，或者将系统驱动到铁磁状态。我们介绍了系统的经典相图作为8-vertex变形和有效温度的功能，我们通过改变可编程耦合的相对强度来控制它们，并且我们表明实验结果与理论分析一致。最后，我们确定其他功能，如果将这些功能添加到这些设备中，则可以使我们实现$ \ Mathbb {z} _2 $ Quantum Spin液体来构建拓扑量子的量子。
We build and probe a $\mathbb{Z}_2$ spin liquid in a programmable quantum device, the D-Wave DW-2000Q. Specifically, we observe the classical 8-vertex and 6-vertex (spin ice) states and transitions between them. To realize this state of matter, we design a Hamiltonian with combinatorial gauge symmetry using only pairwise-qubit interactions and a transverse field, i.e., interactions which are accessible in this quantum device. The combinatorial gauge symmetry remains exact along the full quantum annealing path, landing the system onto the classical 8-vertex model at the endpoint of the path. The output configurations from the device allows us to directly observe the loop structure of the classical model. Moreover, we deform the Hamiltonian so as to vary the weights of the 8 vertices and show that we can selectively attain the classical 6-vertex (ice) model, or drive the system into a ferromagnetic state. We present studies of the classical phase diagram of the system as function of the 8-vertex deformations and effective temperature, which we control by varying the relative strengths of the programmable couplings, and we show that the experimental results are consistent with theoretical analysis. Finally, we identify additional capabilities that, if added to these devices, would allow us to realize $\mathbb{Z}_2$ quantum spin liquids on which to build topological qubits.
