Volume 128, Number 2, October 2019
|Number of page(s)||7|
|Published online||03 January 2020|
Mimicking disorder on a clean graph: Interference-induced inhibition of spread in a cyclic quantum random walk
Harish-Chandra Research Institute, HBNI - Chhatnag Road, Jhunsi, Allahabad 211 019, India
Received: 7 June 2019
Accepted: 1 November 2019
We quantitatively differentiate between the spreads of discrete-time quantum and classical random walks on a cyclic graph. Due to the closed nature of any cyclic graph, there is additional “collision”-like interference in the quantum random walk along with the usual interference in any such walk on any graph, closed or otherwise. We find that the quantum walker exhibits inhibition of spread in comparison to the classical one, even in the absence of disorder, a phenomenon that is potentially attributable to the additional interference in the quantum case. This is to be contrasted with the situation on open graphs, where the quantum walker, being effectively denied the collision-like interference, garners a much higher spread than its classical counterpart. Inhibition of spread also occurs on open graphs, but with insertion of disorder. We use the Shannon entropy of the position probability distribution to quantify the spread of the walker in both quantum and classical cases. We find that for a given number of vertices on a cyclic graph, the entropy with respect to number of steps for the quantum walker saturates, on average, to a value lower than that for the corresponding classical one. We also analyze variations of the entropies with respect to system size, and look at the corresponding asymptotic growth rates.
PACS: 05.40.Fb – Random walks and Levy flights / 03.65.-w – Quantum mechanics
© EPLA, 2020
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.