Quantum advantage for communication tasks in networks

• Grant number: 23/02575-2
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Effective date (Start): June 01, 2023
• Effective date (End): August 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Rafael Luiz da Silva Rabelo
• Grantee: Pedro Nóbrega Lauand
• Supervisor: Elie Wolfe
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Research place: Perimeter Institute for Theoretical Physics, Canada
• Associated to the scholarship: 22/03792-4 - Bell nonlocality on quantum networks, BP.MS

Abstract

Bell's theorem shows that local measurements of an entangled state create nonlocal quantum correlations, a fundamental signature of quantum physics. Bell inequalities provide standard methods to detect such nonlocal correlations, and constitute a powerful toolbox with various applications. More generally, we can see Bell's theorem as the impossibility of providing a classical causal explanation to certain quantum phenomena, and Bell inequalities as specific tasks in which quantum correlations may give an advantage. In this project, we would like to explore scenarios beyond the ones proposed by Bell which take into account independent sources and messages from distant parties in the experiment. To this end, we are going to focus on the Evans scenario, a causal structure in which it is unknown whether it can give rise to quantum non-classical correlations. We propose several avenues to explore the quantum correlations in this elusive scenario: resorting to interventions, rather than pure passive observations, in order to reveal quantum non-classicality, considering prepare-and-measure type protocols where quantum messages can be transmitted in a network with the assistance of entanglement, and using tools of non-convex optimization to propose new Bell-like inequalities for communication tasks in networks. Our main objective is to explore such strategies and inequalities to find quantum violations of the Evans scenario. (AU)