Quantum and classical optics–emerging links

Abstract

Quantum optics and classical optics are linked in ways that are becoming apparent as a result of numerous recent detailed examinations of the relationships that elementary notions of optics have with each other. These elementary notions include interference, polarization, coherence, complementarity and entanglement. All of them are present in both quantum and classical optics. They have historic origins, and at least partly for this reason not all of them have quantitative definitions that are universally accepted. This makes further investigation into their engagement in optics very desirable. We pay particular attention to effects that arise from the mere co-existence of separately identifiable and readily available vector spaces. Exploitation of these vector-space relationships are shown to have unfamiliar theoretical implications and new options for observation. It is our goal to bring emerging quantum-classical links into wider view and to indicate directions in which forthcoming and future work will promote discussion and lead to unified understanding.

Quantum correlations in separable multi-mode states and in classically entangled light

“…(28) we can say that the polarization-cebit of the beam pair is entangled with its position-cebit [19]. Eberly et al [63] generalized the notion of classical entanglement even further, advocating an inherent link between quantum and classical optics, uniting them via common elementary notions of interference, polarization, coherence, complimentarity and entanglement. In their view, the association of entanglement with quantum theory is unnecessary and there is no need in identifying two different types of entanglement as we, following [19] and others, did above.…”

Bell violations with entangled and non-entangled optical fields

“…BCHSH violations by themselves do not rule out the possibility of constructing local-realistic models that are in full accordance with physical phenomena (see, e.g., [15][16][17][18][19][20][21]). This is so because the BCHSH inequality does not derive from the sole assumptions of realism and locality.…”

“…In a broad sense, though, entanglement is nonetheless behind our Bell violations, because η AB itself is non-factorable: it cannot be written as a product of two functions, whereby each function depends on a single degree of freedom. This feature may be taken as the very definition of entanglement [14][15][16].…”

Polarization coherence theorem

“…We join them to polarization P via the Polarization Coherence Theorem, a tight equality:Centuries after Thomas Young's famous double-slit interference experiment [1], quantification of coherence as a contextual resource (see [2]) is just now being examined (see [3,4]), and experimental evidence of polarization coherence in a previously unexplored context has been reported, exposing a new coherence triad [5].The theorem of the title arises from the recognition that polarization is a two-party property, even in common usage. A polarized electorate means two things: (a) opinions within the population favor only a few political factions and (b) this occurs within a specified background (the voting public, but not kindergarten school children).…”

“…Centuries after Thomas Young's famous double-slit interference experiment [1], quantification of coherence as a contextual resource (see [2]) is just now being examined (see [3,4]), and experimental evidence of polarization coherence in a previously unexplored context has been reported, exposing a new coherence triad [5].…”