Quandoop: A Classical Simulator of Quantum Walks on Computer Clusters

Abstract

We describe software Quandoop, a novel simulator of discrete-time quantum walks using high-performance computing (HPC) with the goal of handling simulations with very large Hilbert spaces. Those simulations are usually restricted to a relatively small number of steps due to memory limitations or reduced processing power. The most important feature of Quandoop when compared to previous simulators is to provide a low cost solution for simulations of quantum walks with extreme memory requirements. Examples of such simulations include quantum walks on fractals or with multiple interacting walkers.Quandoop uses Apache Hadoop to parallelize the calculations on a computer cluster, thus reducing the amount of time required to perform the quantum walk simulation and allowing its execution with more steps. Our simulator takes the input as text files containing the initial state, the evolution operators and the description of simulation parameters. This approach allows the integration with other quantum walk simulators such as HiPerWalk or QWalk. After running the necessary calculations in parallel, Quandoop outputs text files describing the results associated to the quantum walk.