Higher order antibunching is not a rare phenomenon
Since the introduction of higher order nonclassical effects, higher order squeezing has been reported in a number of different physical systems but higher order antibunching is predicted only in three particular cases. In the present work, we have shown that the higher order antibunching is not a rare phenomenon; rather it can be seen in many simple optical processes. To establish our claim, we have shown it in the six wave mixing process, four wave mixing process and second harmonic generation process.
What we did?
The present work strongly establishes the fact that HOA is not a rare phenomenon. In the case of an
interaction of an intense electromagnetic field with a third-order nonlinear medium it was reported
that the degree of antibunching (d(l)) can be tuned because they depend strongly on the phase of the input
field which can be tuned. This is not the case with any of the physical systems studied in the present work.
It is also clear that the higher order antibunching would not have been observed if we have considered
first-order operator solutions (first order in g); on the other hand, if we use second-order operator solutions,
then the depth of nonclassicality is found to increase monotonically with the increase of the input photon
number (|α|2). Possibly this monotonic increment will be ceased by the higher order perturbation terms.
It is also observed that if we assume that the
anharmonic constant and
number of photon initially present in
the pump mode are the same for all three cases, then the depth of nonclassicality is the same in the four wave
mixing and second harmonic generation process and it is more in the six wave mixing process.
The present work opens up the possibility of studying higher order nonclassical effects from a new perspective.
This is also important from the application point of view because any
probabilistic single-photon source used
for quantum cryptography has to satisfy the condition for higher order antibunching. Therefore, the simple
prescription followed in the present work may help us to compare the existing sources of a single photon.
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