Condensation of Cooper Triples

TL;DR

This paper explores the theoretical possibility of a new type of many-body condensate formed by three-body fermionic bound states, called Cooper triples, which could exhibit bosonic behavior despite their fermionic constituents.

Contribution

It introduces the concept of Cooper triple condensation, proposing a variational wave function and analyzing the ground-state energy, extending the BCS theory to three-body fermionic systems.

Findings

Cooper triples can form a condensate at zero center-of-mass momentum.

The proposed variational wave function models the condensate effectively.

Ground-state energy calculations support the feasibility of Cooper triple condensation.

Abstract

The condensation of Cooper pairs, originating from the Fermi-surface instability due to a weakly attractive interaction between two fermions, opened a new frontier for exploring many-body physics in interdisciplinary contexts. In this work, we discuss the possible condensation of Cooper triples, which are three-body counterparts of Cooper pairs for three-component fermions with a three-body attraction. Although each composite trimer-like state obeys the Fermi-Dirac statistics, its aggregate can form a condensate at zero center-of-mass momentum in the presence of the internal degrees of freedom associated with the relative momenta of constituent particles of momenta close to the Fermi surface. Such condensation can be regarded as bosonization in infinite-component fermions. We propose a variational wave function for the condensate of Cooper triples in analogy with the Bardeen-Cooper-Schrieffer ground state and obtain the ground-state energy.