Generating superposition of up-to three photons for continuous variable quantum information processing.

We develop an experimental scheme based on a continuous-wave (cw) laser for generating arbitrary superpositions of photon number states. In this experiment, we successfully generate superposition states of zero to three photons, namely advanced versions of superpositions of two and three coherent states. They are fully compatible with developed quantum teleportation and measurement-based quantum operations with cw lasers.

Observation of -9 dB quadrature squeezing with improvement of phase stability in homodyne measurement.

We observe -9.01+/-0.14 dB of squeezing and +15.