Parrondo's paradox for three discrete-time quantum walks with distinct shift operators

Abstract

Parrondo's paradox describes a surprising phenomenon in which certain combinations of biased quantum walks result in an unexpected reversal of their bias direction. To date, research on this effect has predominantly focused on one-dimensional discrete-time quantum walks that employ fixed sequences of two or three quantum coins, paired with a single shift operator. In this work, we first introduce a wide class of unitary shift operators which allow for three movement options (left, right or stay in place) of a walker in one time step, and we then demonstrate that Parrondo's paradox can also arise with a single coin and three distinct shift operators. Furthermore, we investigate how this paradox influences the time evolution of quantum entanglement between the walker and the coin in such quantum walks.