Parametric amplification of vacuum fluctuations is crucial in modern quantum optics, enabling the creation of squeezing and entanglement. We demonstrate the parametric amplification of vacuum fluctuations for matter waves using a spinor F = 2(87) Rb condensate. Interatomic interactions lead to correlated pair creation in the m(F) = +/- 1 states from an initial m(F) = 0 condensate, which acts as a vacuum for m(F) not equal 0. Although this pair creation from a pure mF 0 condensate is ideally triggered by vacuum fluctuations, unavoidable spurious initial m(F) = +/- 1 atoms induce a classical seed which may become the dominant triggering mechanism. We show that pair creation is insensitive to a classical seed for sufficiently large magnetic fields, demonstrating the dominant role of vacuum fluctuations. The presented system thus provides a direct path towards the generation of nonclassical states of matter.
|