论文标题

Markov链在非规范图中更快的量子混合量较少

Faster quantum mixing of Markov chains in non-regular graph with fewer qubits

论文作者

Li, Xinyin, Shang, Yun

论文摘要

固定分布的采样是基于马尔可夫链算法的基本任务之一,并且在机器学习,组合优化和网络科学方面具有重要的应用。对于量子情况,可以将来自马尔可夫链的Q采样构建,以制备具有任意接近固定分布的平方根而不是从固定分布的经典采样的量子状态。在本文中,与现有结果相比,所有可逆的马尔可夫链的新Q采样算法都是由离散时间的量子步行构建的,并且工作没有任何限制。从详细的角度来看,我们构建了一种Q采样算法,该算法不仅可以加速非规范图,而且还可以加快常规图的现有量子算法的速度。在非规范图中,量子快速算法的调用加速了现有的离散时间和连续时间案例的现有最新QS采样算法,尤其是在稀疏图上。与现有算法相比,我们减少了log n,其中n是图顶点的数量。在常规图中,我们的结果与其他量子算法相匹配,与经典案例相比,我们对马尔可夫链间隙的依赖达到了二次加速。在这两种情况下,我们减少了与现有结果相比所需的Ancilla Qubits数量。在某些广泛使用的图和一系列稀疏图中,很难快速到达固定分布,我们的算法是第一个实现经典案例的完整二次加速度(没有log factor)的算法,而无需任何限制。为了扩大成功概率幅度扩增。我们在固定状态下建立了一个新的反思,而Ancilla Qubits的固定状态可能会有独立的应用。

Sampling from the stationary distribution is one of the fundamental tasks of Markov chain-based algorithms and has important applications in machine learning, combinatorial optimization and network science. For the quantum case, qsampling from Markov chains can be constructed as preparing quantum states with amplitudes arbitrarily close to the square root of a stationary distribution instead of classical sampling from a stationary distribution. In this paper, a new qsampling algorithm for all reversible Markov chains is constructed by discrete-time quantum walks and works without any limit compared with existing results. In detail, we build a qsampling algorithm that not only accelerates non-regular graphs but also keeps the speed-up of existing quantum algorithms for regular graphs. In non-regular graphs, the invocation of the quantum fast-forward algorithm accelerates existing state-of-the-art qsampling algorithms for both discrete-time and continuous-time cases, especially on sparse graphs. Compared to existing algorithms we reduce log n, where n is the number of graph vertices. In regular graphs, our result matches other quantum algorithms, and our reliance on the gap of Markov chains achieves quadratic speedup compared with classical cases. For both cases, we reduce the number of ancilla qubits required compared to the existing results. In some widely used graphs and a series of sparse graphs where stationary distributions are difficult to reach quickly, our algorithm is the first algorithm to achieve complete quadratic acceleration (without log factor) over the classical case without any limit. To enlarge success probability amplitude amplification is introduced. We construct a new reflection on stationary state with fewer ancilla qubits and think it may have independent application.

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