Topology Induced Macroscopic Quantum Coherence in Josephson Junction Networks

TL;DR

This paper explores how the topology of Josephson junction networks influences quantum coherence, demonstrating that specific network structures like comb graphs can induce spatial Bose-Einstein condensation, which can be experimentally detected.

Contribution

It introduces the concept that network topology can induce macroscopic quantum coherence in Josephson junctions, with detailed analysis of comb graphs and a proposed experiment for detection.

Findings

Topology affects quantum properties of bosons in networks

Comb graphs induce spatial Bose-Einstein condensation

Proposed experiment to detect condensation in Josephson networks

Abstract

We argue that Josephson junction networks may be engineered to allow for the emergence of new and robust quantum coherent states. We provide a rather intuitive argument showing how the change in topology may affect the quantum properties of a bosonic particle hopping on a network. As a paradigmatic example, we analyze in detail the quantum and thermodynamic properties of non-interacting bosons hopping on a comb graph. We show how to explicitly compute the inhomogeneities in the distribution of bosons along the comb's fingers, evidencing the effects of the topology induced spatial Bose-Einstein condensation characteristic of the system. We propose an experiment enabling to detect the spatial Bose-Einstein condensation for Josephson networks built on comb graphs.