Quantum walks with inhomogeneous coins

Abstract

Quantum walks, the quantum analogs of classical random walks, have become powerful tools in quantum information processing, offering unique advantages in areas such as quantum computation, search algorithms, and quantum transport. While homogeneous quantum walks with uniform coin operations have been well studied, introducing inhomogeneity - by varying the coin operator or evolution across time and space opens new avenues for controlling the dynamics and properties of quantum systems. Our research has explored the impact of such inhomogeneous quantum walks, yielding two significant results. First, we demonstrated Parrondo's paradox in discrete-time quantum walks using space- and time-dependent coins, achieving paradoxical outcomes without requiring higher-dimensional coins or decoherence, thus enhancing the practicality of implementations [1]. Second, by introducing a Gaussian-profiled coin rotation angle, we showed that this configuration not only improves localization of the walker's probability distribution but also generates maximal entanglement rapidly and a correlation that is robust against decoherence [2]. These findings underscore the potential of inhomogeneous quantum walks for more efficient and resilient quantum technologies.