Spin-flip induced superfluidity in a ring of spinful hard-core bosons

TL;DR

This paper solves the t-J Hamiltonian for spinful hard-core bosons in a ring, revealing unique ground state behaviors and intrinsic spin-induced gauge fields that support superfluidity, with implications for experimental verification.

Contribution

It provides an exact solution for the energy spectrum of spinful bosonic rings and uncovers the role of spin-induced gauge fields in superfluidity, differing from fermionic systems.

Findings

Ground state is ferromagnetic only for N=2,3 bosons

Energy levels are quantized due to spin and cyclic permutations

Intrinsic spin-generated gauge fields support superfluidity

Abstract

The t - J Hamiltonian of the spinful hard-core bosonic ring in the Nagaoka limit is solved. The energy spectrum becomes quantized due to presence of spin, where each energy level corresponds to a cyclic permutation state of the spin chains. The ground state is true ferromagnetic when the ring contains N = 2, 3 spinful hard-core bosons; for all other N it is a mixture of the ferromagnetic and non-ferromagnetic states. This behaviour is different from the fermionic ring, where ground state is true ferromagnetic only for N = 3. It is shown that the intrinsic spin generated gauge fields are analogous to the synthetic gauge fields generated by rotation of either the condensate or the confining potential. It is argued that the low lying excited levels of the spin flipped states intrinsically support the superfluidity. Possible ways to experimentally verify these results are also discussed.