Spontanous spin squezing in a rubidium BEC

TL;DR

This paper reports on spontaneous spin squeezing in a rubidium Bose-Einstein condensate driven by collisional interactions, achieving 1.3 dB of metrological squeezing with potential applications in atom interferometry.

Contribution

It demonstrates spontaneous spin squeezing in a standard BEC setup without requiring cavities or Feshbach resonances, highlighting a new method for generating entangled atomic states.

Findings

Achieved 1.3+/-0.4 dB spin squeezing with 5000 atoms

Observed spin squeezing in a standard Ramsey sequence

Method applicable to atom interferometry without complex setups

Abstract

We describe an experiment where spin squeezing occurs spontaneously within a standard Ramsey sequence driving a two-component Bose-Einstein condensate (BEC) of 87Rb atoms trapped in an elongated magnetic trap. Multiparticle entanglement is generated by state-dependent collisional interactions, despite the near-identical scattering lengths of the spin states in 87Rb. In our proof-of-principle experiment, we observe a metrological spin squeezing that reaches 1.3+/-0.4dB for 5000 atoms, with a contrast of 90+/-1%. The method may be applied to realize spin-squeezed BEC sources for atom interferometry without the need for cavities, state-dependent potentials or Feshbach resonances.