  One of the most fundamental quantum states of light is squeezed vacuum, in
which noise in one of the quadratures is less than the standard quantum noise
limit. Significant progress has been made in the generation of optical squeezed
vacuum and its utilization for numerous applications. However, it remains
challenging to generate, manipulate, and measure such quantum states in
nanophotonics with performances required for a wide range of scalable quantum
information systems. Here, we overcome this challenge in lithium niobate
nanophotonics by utilizing ultrashort-pulse phase-sensitive amplifiers for both
generation and all-optical measurement of squeezed states on the same chip. We
generate a squeezed state spanning over more than 25 THz of bandwidth
supporting only a few optical cycles, and measure a maximum of 4.9 dB of
squeezing ($\sim$11 dB inferred). This level of squeezing surpasses the
requirements for a wide range of quantum information systems. Our results on
generation and measurement of few-optical-cycle squeezed states in
nanophotonics enable a practical path towards scalable quantum information
systems with THz clock rates and open opportunities for studying non-classical
nature of light in the sub-cycle regime.
