QLunch: Marc-Olivier Renou

Speaker: Marc-Olivier Renou

Title: Fermions are more nonlocal than Bosons and distinguishable particles

Abstract: Bell's theorem rules out a world containing only classical particles. It does so by exhibiting an experiment whose correlations, produced by quantum particles, cannot be reproduced within classical information theory. Remarkably, it rests on the minimal assumption that information is carried by particles travelling at finite speed — no stronger physical postulate is needed — and on nothing more than the standard Alice–Bob scenario.

Here we rule out a world containing only distinguishable particles and bosons. We propose an experiment based on identical fermions whose correlations cannot be reproduced within standard quantum information theory, that is, by distinguishable particles or identical bosons. Our result rests on the same minimal assumption, but is formulated in a new scenario inspired by distributed computing: indistinguishable fermions sent through a quantum network produce correlations that distinguishable particles and bosons can match only if granted additional communication. In this precise sense, fermions are fundamentally more nonlocal than bosons or distinguishable particles, which makes anticommutation and indistinguishability unavoidable operational resources.

Our work therefore establishes device-independently the existence of particles beyond the distinguishable and bosonic ones, and shows that fermionic information theory can outperform standard quantum information theory for certain distributed tasks. Quantum information textbooks built on qubits alone thus miss genuine possibilities for distributed processing: a single fermionic bit, or febit, can achieve what no number of qubits can without extra communication.

Based on https://arxiv.org/abs/2606.12363