  We report on the experimental observation of quantum-network-compatible light
described by a non-positive Wigner function. The state is generated by photon
subtraction from a squeezed vacuum state produced by a continuous wave optical
parametric amplifier. Ideally, the state is a coherent superposition of odd
photon number states, closely resembling a superposition of weak coherent
states (a Schroedinger cat), with the leading contribution from a single photon
state in the low parametric gain limit. Light is generated in a nearly perfect
spatial mode with a Fourier-limited frequency bandwidth which matches well
atomic quantum memory requirements. The source is also characterized by high
spectral brightness with about 10,000 and more events per second routinely
generated. The generated state of light is the ultimate input state for testing
quantum memories, quantum repeaters and linear optics quantum computers.
