Efficient photon triplet generation in integrated nanophotonic waveguides

Abstract

Generation of entangled photons in nonlinear media constitutes a basic building block of modern photonic quantum technology. Current optical materials are severely limited in their ability to produce three or more entangled photons in a single event due to weak nonlinearities and challenges achieving phase-matching. We use integrated nanophotonics to enhance nonlinear interactions and develop protocols to design multimode waveguides that enable sustained phase-matching for third-order spontaneous parametric down-conversion (TOSPDC). We predict a generation efficiency of 0.13 triplets/s/mW of pump power in TiO₂-based integrated waveguides, an order of magnitude higher than previous theoretical and experimental demonstrations. We experimentally verify our device design methods in TiO₂ waveguides using third-harmonic generation (THG), the reverse process of TOSPDC that is subject to the same phase-matching constraints. We finally discuss the effect of finite detector bandwidth and photon losses on the energy-time coherence properties of the expected TOSPDC source.

Multiphoton nonclassical light from clusters of single-photon emitters

“…lead to the curves that are indistinguishable in the figure. In both cases, g (2) <1 and g (3) <1 for any number of emitters in a cluster.…”

“…One way is nonlinear optical interactions of higher orders, leading to the emission of photon triplets, quadruples and so on [1]. Realization of such processes remains a challenge, although there are several experimental attempts to generate photon triplets through the third-order interaction in nonlinear crystals [2], waveguides [3], and fibers [4]. Generation of photon triplets from solid-state emitters, such as 'quantum dot molecules' [5] is another option.…”

Quasi-phase-matched χ(3) -parametric interactions in sinusoidally tapered waveguides

“…5(a). Panels (b,c) show the 2D representation of Γ THG (equivalent to the phase-matching function of photon triplets [15,16]) over which the energy and momentum conservation conditions are satisfied for TH at 500 and 516 nm, respectively. Because of the weakness of the sidelobes, the spectral purity of three downconverted photons out of one pump photon (reverse process of TH generation) is anticipated to be high.…”

“…For instance: (i) Spontaneous four-wave mixing in waveguides, in which two photons will coalesce to generate two other photons, has been enabled via balancing the waveguide and material dispersion in narrow spectral range near the zero dispersion wavelength, or exploiting the nearly-phase matched range, where the coherence length is much longer than the structure length [9][10][11][12]. (ii) Third-harmonic generation has been enhanced via nonlinear interactions in multimode waveguides [13][14][15], using a hybrid photonic crystal fibre to allow interaction between a pump wave with its third-harmonic, both in the fundamental mode [16], or exploiting slow-light effect introduced by photonic crystals [17].…”

Fundamental-mode third harmonic generation in microfibers by pulse-induced quasi-phase matching

“…This issue has been given more attention as the reverse process of triple photon generation (TPG), which shares the same phase matching condition with THG, is useful for quantum optics applications [9,16]. However, it is very difficult to overcome chromatic dispersion to reach phase matching between the fundamental pump and third harmonic modes in fibers, so very few attempts had been reported.…”