Mathematics

Title: "Quantum Advantage through Communication Tasks: From Unbounded Separations to the Usefulness of Nonlocality"

Abstract: Quantum advantage is operational: whether a quantum resource is useful depends on the task and on which other resources are constrained. Communication tasks make this dependence especially clear. In this talk, I will illustrate this principle in one-way communication scenarios.

First, I consider graph-based relation reconstruction. In the absence of shared resources, we find graph families for which the quantum communication cost remains fixed while the classical cost grows without bound. Fixing the communication instead to one classical bit reveals a second separation, now between assisting resources: one ebit is sufficient, whereas the shared randomness required grows without bound.

This shifts attention to the shared correlation and raises a broader question: is every Bell-nonlocal correlation advantageous in some bounded classical communication task? For tasks with linear payoffs, wire-cutting maps a communication task to an associated Bell inequality, making Bell violation equivalent to communication advantage in the corresponding setting. Wire-reading takes a complementary route: by including the transmitted classical symbol among the observed variables, it enables the construction of tasks adapted to nonlocal facets of the no-signalling polytope. I will also present one-bit tasks in which Hardy-type correlations with dichotomic inputs achieve positive payoffs, while shared-randomness-assisted strategies achieve at most zero. Finally, I show that communication performance can witness dimension: in one task, two qutrits attain the quantum optimum while every two-qubit strategy falls short.

Bio: Dr. Sumit Rout received his PhD in Physics from the University of Gdańsk in 2026 under the supervision of Prof. Paweł Horodecki, a pioneer of quantum entanglement theory and a leading figure in quantum information science. Rooted in quantum foundations, his research is increasingly directed toward quantum information science, with emerging interests in computational complexity and quantum algorithms. A unifying theme of his work is to determine when, and precisely why, genuinely quantum features enable provable advantages in computation, communication, thermodynamics, and other information-processing tasks.

Dr. Rout is currently a postdoctoral researcher at the International Centre for Theory of Quantum Technologies (ICTQT), University of Gdańsk, where he works with Michał Studziński in the Quantum Devices in Computer Science group. The group develops algorithms and methods for quantum computation, measurements, data transmission, and error correction, with particular emphasis on exploiting symmetries in quantum systems. He has authored or co-authored multiple top-rated peer-reviewed publications and preprints.