EPJ Quantum Technol. (2018) 5: 1
https://doi.org/10.1140/epjqt/s40507-017-0065-9

Research

Robust quantum state engineering through coherent localization in biased-coin quantum walks

¹ Centre for Secure Information Technologies (CSIT), Queen’s University, Belfast, BT7 1NN, United Kingdom
² Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen’s University, Belfast, BT7 1NN, United Kingdom
³ Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom

^* e-mail: hmajury01@qub.ac.uk

Received: 25 July 2017
Accepted: 21 December 2017
Published online: 5 January 2018

Abstract

We address the performance of a coin-biased quantum walk as a generator for non-classical position states of the walker. We exploit a phenomenon of coherent localization in the position space - resulting from the choice of small values of the coin parameter and assisted by post-selection - to engineer large-size coherent superpositions of position states of the walker. The protocol that we design appears to be remarkably robust against both the actual value taken by the coin parameter and strong dephasing-like noise acting on the spatial degree of freedom. We finally illustrate a possible linear-optics implementation of our proposal, suitable for both bulk and integrated-optics platforms.