Speaker: Professor Matteo G.A.Paris，University of Milan

Inviter: 张悦

Title: Chiral quantum walks and possible applications

Language: English

Time & Venue: 2026.09.24 10:00-11:00 N620

Abstract: Quantum walks are the quantum mechanical counterpart of classical random walks and provide a general and flexible tool to describe the quantum propagation of a particle or an excitation in a network, i.e. a discrete structure modeled as a graph. Besides the fundamental interest, quantum walks represent a valuable tool to describe, design and optimize energy transport in artificial or biological systems. Continuous-time quantum walks (CTQW) on graphs are traditionally defined as the quantum analogue of classical random walks (RW), by promoting the classical transfer matrix, i.e. the RW graph Laplacian, to an Hamiltonian. However, this association does not encompass all the possible quantum evolutions of a walker on a graph, thus strongly limiting the set of exploitable quantum Hamiltonians to achieve quantum enhancement in specific tasks. A question thus arises on whether it is possible to define more general quantum walks on a graph, by considering all Hermitian Hamiltonians compatible with a given graph topology, and how do these generalized QWs compare with their classical analogues. In this talk, I present a systematic approach to chiral quantum walks, introducing a full characterization of all the possible Hamiltonians describing the time evolution over a given topology. As applications, we address the problem of optimally routing classical and quantum information encoded in the position of a quantum walker on the simplest graphs apt to this task, and prove that chirality may be exploited to achieve the quantum speed limit in search algorithms on graphs.