The Kibble-Zurek mechanism (KZM) captures the essential physics of nonequilibrium quantum phase transitions with symmetry breaking. KZM predicts a universal scaling power law for the defect density which is fully determined by the system's critical exponents at equilibrium and the quenching rate. We experimentally tested the KZM for the simplest quantum case, a single qubit under the Landau-Zener evolution, on an open access IBM quantum computer (IBM-Q). We find that for this simple one-qubit model, experimental data validates the central KZM assumption of the adiabatic-impulse approximation for a well isolated qubit. Furthermore, we report on extensive IBM-Q experiments on individual qubits embedded in different circuit environments and topologies, separately elucidating the role of crosstalk between qubits and the increasing decoherence effects associated with the quantum circuit depth on the KZM predictions. Our results strongly suggest that increasing circuit depth acts as a decoherence source, producing a rapid deviation of experimental data from theoretical unitary predictions.
翻译:KOBT- Zurek 机制( KZM) 捕捉了无平衡量级转换和对称断裂的基本物理。 KZM 预测了系统在平衡和电解速率上的关键指数所完全决定的缺陷密度的通用缩放功率法。 我们实验了KZM 的简单量子案例,Landau-Zener进化下的一个单一qubit,在开放访问 IBM 量级计算机( IBM-Q ) 上。 我们发现,对于这个简单的单方位模型,实验数据验证了KZM 中心假设的偏差- 偏差度近似值。 此外, 我们报告了关于嵌入不同电路环境和地形的个体Q 的广泛IBM- 实验, 分别揭示了昆虫之间的交叉对话作用和与KZM 预测的量子电路深度相关的日益分解效应。 我们的结果表明, 电路深度的增加作为分解源, 导致实验性理论性数据与理论性预测的迅速偏离。