  Number state filtering in coherent states leads to sub-Poissonian photon
statistics. These states are more suitable for phase estimation when compared
with the coherent states. Nonclassicality of these states is quantified in
terms of the negativity of the Wigner function and the entanglement potential.
Filtering of the vacuum from a coherent state is almost like the
photon-addition. However, filtering makes the state more resilient against
dissipation than photon-addition. Vacuum state filtered coherent states perform
better than the photon-added coherent states for a two-way quantum key
distribution protocol. A scheme to generate these states in multi-photon
atom-field interaction is presented.
