Non-classicality of photon added coherent and thermal radiations

Abstract

Production and analysis of non-Gaussian radiation fields has evinced a lot of attention recently. Simplest way of generating such non-Gaussians is through adding (subtracting) photons to Gaussian fields. Interestingly, when photons are added to classical Gaussian fields, the resulting states exhibit non-classicality. Two important classical Gaussian radiation fields are coherent and thermal states. Here, we study the non-classical features of such states when photons are added to them. Nonclassicality of these states shows up in the negativity of the Wigner function. We also work out the entanglement potential, a recently proposed measure of non-classicality for these states. Our analysis reveals that photon added coherent states are non-classical for all seed beam intensities; their non-classicality increases with the addition of more number of photons. Thermal state exhibits non-classicality at all temperatures, when a photon is added; lower the temperature, higher is their non-classicality.

Quantifying Process Nonclassicality in Bosonic Fields*

“…Therefore, the nonclassicality of the photon addition process increases with 𝑛. This is consistent with the previous observation [39,48] where the authors employed the entanglement potential as the nonclassicality measure and computed them numerically for single, two and three photon added coherent states.…”

A geometric measure of non-classicality

“…This gives us the opportunity to compare our present distance-type results to those given by a non-classicality measure of a totally different origin, the EP. Our formula (11) depicted in figure 2 describes the behaviour of  Q in close agreement with the investigation in [39]. It is sufficient to compare our figure 2(b) and the corresponding figure 3 in [39] to see their similarity.…”

“…As such, the task of measuring non-classicality is transferred to an evaluation of a two-mode entanglement which is not a simpler problem in most cases of interest. Fortunately, for some lower numbers of added photons to a coherent state the EP could be evaluated in [39]. This gives us the opportunity to compare our present distance-type results to those given by a non-classicality measure of a totally different origin, the EP.…”

“…a 2 , but are well separated for low beam intensity, being larger for higher numbers of photons added to a weak coherent state. Non-classicality of a p-photon-added coherent state was discussed in [39] by evaluating its entanglement potential (EP). This measure of non-classicality was defined as the entanglement generated by a non-classical state when mixed with the vacuum state in a balanced beam splitter [40].…”

Quantifying Athermality and Quantum Induced Deviations from Classical Fluctuation Relations

“…The states and are diagonal in the energy eigenbasis and therefore are classical in the sense that they are devoid of coherence. Nonetheless, they are non-Gaussian and have negative Wigner functions [ 45 , 65 , 66 , 67 , 68 ], traits which are considered non-classical in the context of quantum optics.…”