  We investigate experimentally the nonlocal phase modulation of
multiple-frequency-mode, continuous-variable entangled twin beams. We use a
pair of electro-optical phase modulators to modulate the entangled probe and
conjugate light beams produced by four-wave mixing in hot Rb vapor. A single
phase modulator in either one of the twin beams reduces the two-mode squeezing
signal, and we find that the modulations interfere nonlocally to modify the
beam correlations. The nonlocal modulation of the beams can produce quantum
correlations among frequency modes of the multimode fields.
