论文标题
投影驱动量子电路中的非额外纠缠水平统计
Nonuniversal Entanglement Level Statistics in Projection-driven Quantum Circuits
论文作者
论文摘要
我们研究随机通用量子电路的输出状态的纠缠状态的级别间距统计数据，在每个时间步骤中，量子位会受到计算基础的有限投影概率。我们遇到了两种相变的投影率：第一个是通过投影测量的量子回路中观察到的体积到区域定律过渡；第二个将大型投影测量率的纯泊泊托泊统计阶段与纠缠频谱中的残留水平排斥率的制度分开，其特征是Wigner-Dyson和Poisson分布之间的非宇宙水平间距统计。通过应用参考文献中引入的张量网络收缩算法。 [1]在巡回时空，我们将第二个投影测量驱动的转变确定为纠缠键的渗透过渡。在随机的两数Qubit单位和通用门集的电路的两个电路中都观察到了相同的行为，包括Google在其Sycamore电路中实现的集合。
We study the level-spacing statistics in the entanglement spectrum of output states of random universal quantum circuits where qubits are subject to a finite probability of projection to the computational basis at each time step. We encounter two phase transitions with increasing projection rate: The first is the volume-to-area law transition observed in quantum circuits with projective measurements; The second separates the pure Poisson level statistics phase at large projective measurement rates from a regime of residual level repulsion in the entanglement spectrum within the area-law phase, characterized by non-universal level spacing statistics that interpolates between the Wigner-Dyson and Poisson distributions. By applying a tensor network contraction algorithm introduced in Ref. [1] to the circuit spacetime, we identify this second projective-measurement-driven transition as a percolation transition of entangled bonds. The same behavior is observed in both circuits of random two-qubit unitaries and circuits of universal gate sets, including the set implemented by Google in its Sycamore circuits.
