Unified Microscopic Theory of a System of Interacting Bosons

TL;DR

This paper develops a unified microscopic theory for interacting bosons like liquid helium-4, explaining superfluidity, quantum correlations, and collective excitations, and extends potential applications to lower-dimensional systems and fermionic systems.

Contribution

It introduces a novel microscopic framework that describes superfluidity and quantum phase transitions in bosonic systems, including new quasi-particle modes and a unified explanation of experimental phenomena.

Findings

Identifies an energy gap as the binding mechanism for superfluidity.

Explains the lambda transition as a result of quantum correlations.

Predicts a new quasi-particle called omon with phonon-like properties.

Abstract

This paper reports the unified microscopic theory of a system of interacting bosons such as liquid $^4He$.Each particle in the system represents a $(q;-q)$ pair moving with a centre of mass momentum K.Particles form bound pairs below $\lambda$-point and have a kind of collection binding between them.The binding is idenified as an energy gap between the superfluid and the normal states of the system.The $\lambda$-transition is a consequence of interparticle quantum correlations.It follows an order-disoder of particles in their phase structure as well as the onset of Bose_ Einstein condensatin in the state of $q={\pi}/d$ and K=0.In addition to the well known modes of collective motion such as photons,rotons, maxons etc.,the superfluid state also exhibits a new kind of quasi-particle,omon,characterised by a phononlike wave of the oscillations of the momentum coordinates of the particle.The theory explains the properties of $He-II$ at quantitative level and vindicates the two-fluid theory of Landau.The paper finally describes the way this theory could help in understanding the superfluidity of 1-D and 2-D systems.It also analyses the possibility of applying this approach to develop similar framework for a fermion system including an atomic nucleus.