Dunjko, Vanja — Quantum advantage in precision measurement with matter-wave solitons

One-dimensional ultracold Bose gases with attractive atom-atom
interactions support bright matter-wave solitons. Once a fundamental
soliton is created, a four-fold quench in the interaction strength
produces two daughter solitons. These, due to quantum fluctuations
atop the mother soliton, are born in a coherent macroscopic
superposition, their relative position described by a nearly
minimum-uncertainty wavefunction. We show how this state can be used
to effect precision measurement. Despite not being an interferometric
scheme, a preliminary analysis shows that it features quantum
advantage: a precision that scales proportionally to N, the number of
particles in the solitons.