Deterministic control of photonic de Broglie waves using coherence optics

Abstract

Photonic de Broglie waves offer a unique property of quantum mechanics satisfying the complementarity between the particle and wave natures of light, where the photonic de Broglie wavelength is inversely proportional to the number of entangled photons acting on a beam splitter. Very recently, the nonclassical feature of photon bunching has been newly interpreted using the pure wave nature of coherence optics [Sci. Rep. 10, 7,309 (2020)], paving the road to unconditionally secured classical key distribution [Sci. Rep. 10, 11,687 (2020)]. Here, deterministic photonic de Broglie waves are presented in a coherence regime to uncover new insights in both fundamental quantum physics and potential applications of coherence-quantum metrology.

Experimental demonstrations of unconditional security in a purely classical regime

“…The asymmetric structure of the coupled MZIs with results in CBW, whose modulation frequency turns out to be doubled (2 Hz), as shown in the region left of the dashed line in Fig. 3 b due to 16 . This doubled frequency is a quantum feature obtained in a classical domain, where it is not the frequency beating.…”

“…This means that the basic scheme of USCKD is composed of two identical MZIs via quantum superposition (see the dotted box) between them. Here, the coupling method for superposition plays an important role 15 , 16 . Unlike the symmetric coupling for USCKD in Fig.…”

“…Unlike the symmetric coupling for USCKD in Fig. 1 , CBW is based on asymmetric coupling, in which the asymmetry represents a phase shift to the second MZI of 16 . In each MZI, two phase bases of each path can be controlled by an acousto-optic modulator (AOM) pair, in which each AOM driving frequency plays a key role for the phase control of the MZI (discussed in experiments).…”

“…Recently, experimental demonstrations of CBW have been successfully performed, where USCKD represents a special state of CBW under the same physics 28 . Thus, CBW as well as USCKD have been understood as a macroscopic feature 15 , 16 . In that sense, conventional understanding of the quantum nature limited to the microscopic world satisfying the uncertainty principle has been intrigued and expanded toward the macroscopic world, such as in the case of Schrodinger’s cat 29 , 30 .…”

On-demand quantum correlation control using coherent photons

“…Because MZI does not distinguish between single photons and coherent light, a macroscopic quantum feature such as Schrödinger's cat can also be manipulated deterministically. Such an example has been discussed for photonic de Broglie waves using coherent light, recently [33]. Experimental demonstrations for Fig.…”