Observation of pairs of atoms at opposite momenta in an equilibrium interacting Bose gas

Quantum fluctuations play a central role in the properties of quantum matter. In non-interacting ensembles, they manifest as non-commuting observables, quantified by Heisenberg inequalities1. presence interactions, additional appear, from which many-body correlations and entanglement arise2. Weak interactions are predicted to deplete Bose–Einstein condensates formation correlated pairs bosons with opposite momenta3,4. Here we report observation these atom depletion an equilibrium interacting Bose gas5. Our measurements atom–atom correlations, both at close-by momenta6,7, allow us characterize state. We also show that share two-mode squeezed states8,9, including relative number squeezing10–12. results illustrate how systems acquire non-trivial result interplay between interactions13. Interactions atoms condensate cause creation atoms. These effects have now been directly observed, confirming long-standing theoretical predictions.