Abstract
We study topological phenomena of quantum walks by implementing a novel protocol that extends the range of accessible properties to the eigenvalues of the walk operator. To this end, we experimentally realise for the first time a split-step quantum walk with decoupling, which allows for investigating the effect of a bulk-boundary while realising only a single bulk configuration. The experimental platform is implemented with the well-established time-multiplexing architecture based on fibre-loops and coherent input states. The symmetry protected edge states are approximated with high similarities and we read-out the phase relative to a reference for all modes. In this way we observe eigenvalues which are distinguished by the presence or absence of sign flips between steps. Furthermore, the results show that investigating a bulk-boundary with a single bulk is experimentally feasible when decoupling the walk beforehand.
Highlights
Phenomena such as the quantum Hall effect [1] and topological insulators [2, 3] aroused vivid interest in the study of the topological properties of physical systems
The continuous-time quantum walk is defined by a Hamiltonian including nearest neighbour hopping, while discrete-time quantum walks (DTQW) describe the discrete time evolution of a walker with an internal degree of freedom on a lattice
This work constitutes the first experimental implementation of a split-step quantum walk with decoupling as proposed in [56, 57], which allows for investigating the effect of a bulkboundary while realising only a single bulk configuration
Summary
Thomas Nitsche , Tobias Geib, Christoph Stahl, Lennart Lorz, Christopher Cedzich, Sonja Barkhofen, Reinhard F Werner and Christine Silberhorn.
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