  Continuous variable encoding of quantum information requires the
deterministic generation of highly correlated quantum states of light in the
form of quantum networks, which, in turn, necessitates the controlled
generation of a large number of squeezed modes. In this work, we present an
experimental source of multimode squeezed states of light at telecommunication
wavelengths. Generation at such wavelengths is especially important as it can
enable quantum information processing, communication, and sensing beyond the
laboratory scale. We use a single-pass spontaneous parametric down-conversion
process in a non-linear waveguide pumped with the second harmonic of a
femtosecond laser. Our measurements reveal significant squeezing in more than
21 frequency modes, with a maximum squeezing value exceeding 2.5 dB. We
demonstrate multiparty entanglement by measuring the state's covariance matrix.
Finally, we show the source reconfigurability by preparing few-node cluster
states and measure their nullifier squeezing level. These results pave the way
for a scalable implementation of continuous variable quantum information
protocols at telecommunication wavelengths, particularly for multiparty,
entanglement-based quantum communications. Moreover, the source is compatible
with additional pulse-by-pulse multiplexing, which can be utilized to construct
the necessary three-dimensional entangled structures for quantum computing
protocols.
