Fast generation of spin-squeezed states in bosonic Josephson junctions

TL;DR

This paper presents methods for rapidly generating highly coherent spin-squeezed states in bosonic Josephson junctions by extending shortcuts to adiabaticity to the many-body Bose-Hubbard model, achieving optimal squeezing scaling.

Contribution

It introduces a novel approach to produce spin-squeezed states quickly in BJJs by applying shortcut protocols to the many-body Hamiltonian, improving efficiency over traditional adiabatic methods.

Findings

Achieves near-optimal squeezing scaling of /N for large atom numbers.

Extends shortcut-to-adiabaticity techniques to many-body Bose-Hubbard systems.

Demonstrates fast generation of highly coherent spin-squeezed states.

Abstract

We describe methods for fast production of highly coherent-spin-squeezed many-body states in bosonic Josephson junctions (BJJs). We start from the known mapping of the two-site Bose-Hubbard (BH) Hamiltonian to that of a single effective particle evolving according to a Schr\"odinger-like equation in Fock space. Since, for repulsive interactions, the effective potential in Fock space is nearly parabolic, we extend recently derived protocols for shortcuts to adiabatic evolution in harmonic potentials to the many-body BH Hamiltonian. The best scaling of the squeezing parameter for large number of atoms N is \xi^2_S ~ 1/N.