Transferência de estados quânticos em redes desordenadas

Abstract

We live in an era of rapid technological advances, where the relentless pursuit of innovations allows us to envision ways to enhance the capacity for processing and storing information. Faced with the limitations of current classical computers in solving complex problems, the need for quantum computers arises, offering greater efficiency and viability for more intricate calculations. This work adopts the approach of using spin networks as quantum channels, a relevant proposal in quantum computing. Initially, we analyze crystalline spin networks, observing that as the network size increases, both probability and fidelity decrease, rendering the system impractical for quantum transmission in short-range networks. We introduce a protocol with hopping g < J at the network edges, analyzing the regimes of g ≪ J and g ≲ J. For g ≪ J, the system behaves like a two-level system due to subspaces generated between the emitter and the receiver. For g ≲ J, we observe a ballistic behavior similar to projectile motion, where the transmitted information travels across the entire network to reach the receiver. The efficiency of these regimes in the "information transmission speed"was also assessed. We also analyze the behavior of the network with correlated local disorder, observing interesting effects. Quantum State Transfer (QST) is of poor quality for random disorder (α = 0) but improves as we increase the correlation involved in the system. We conclude that correlation in disorder makes the system more robust, resulting in better QST quality. Allowing the induction of disorder may be more interesting and feasible than designing highly specific chains, making implementation in quantum computers more complex. This work seeks to encourage the search for quantum communication protocols in disordered spin chains, promoting the advancement of this innovative technology.