Generation of correlated photons in nanoscale silicon waveguides

Abstract

.We experimentally study the generation of correlated pairs of photons through four-wave mixing (FWM) in embedded silicon waveguides. The waveguides, which are designed to exhibit anomalous group-velocity dispersion at wavelengths near 1555 nm, allow phase matched FWM and thus efficient pair-wise generation of non-degenerate signal and idler photons. Photon counting measurements yield a coincidence-to-accidental ratio (CAR) of around 25 for a signal (idler) photon production rate of about 0.05 per pulse. We characterize the variation in CAR as a function of pump power and pump-to-sideband wavelength detuning. These measurements represent a first step towards the development of tools for quantum information processing which are based on CMOS-compatible, silicon-on-insulator technology.

CMOS-compatible photonic devices for single-photon generation

“…3, when there is only one pump, the generated photons are at two different frequencies ωs and ω i , satisfying energy conversion ωs + ω i = 2ωp and phase matching ks + k i + 2 P − 2kp = 0; while when there are two pump waves at different frequencies ω p1 and ω p2 , the generated photons are frequency degenerate at ω s,i , also meeting the requirement of energy conversion 2ω s,i = ω p1 + ω p2 and phase matching 2k s,i + (P 1 + P 2 ) − k p1 − k p2 = 0 [25]. The former process can be used for heralded single-photon generation [26][27][28][29][30][31][32][33][34][35][36][37], and the latter can be used for indistinguishable photon-pair generation [38][39][40]. Phase matching is achieved by engineering the dispersion profile of the device through designing the device geometry and tailoring the waveguide core-cladding index contrast by the use of different cladding materials.…”

On-chip quantum interference between silicon photon-pair sources

“…[5,6] To date, increasingly complex quantum photonic circuits, [7][8][9] sources, [10][11][12][13] and detectors [14] have been shown independently, but the integration of more than one of these elements has proven difficult. Focussing on source-circuit integrations, initial demonstrations have consisted of a photon-pair source with passive directional coupler elements, forming a quantum relay, [15] and a source of colour-segregated, polarisation-entangled photons, using an on-chip polarisation rotator.…”

Generation and manipulation of entangled photons on silicon chips

“…Due to the high χ (3) nonlinearity of silicon in the telecommunication band (e.g. more than 100 times higher than that of silica) and the submicrometer scale mode field diameter [50,51], correlated photons can be efficiently generated via spontaneous FWM in an SWW [15,16,52,53]. Moreover, the Raman noise photons in a single-crystalline silicon core, which exhibit a sharp spectral peak that is 15.6 THz away from the pump frequency, can be easily eliminated with wavelength filters.…”

“…With the use of waveguides, several quantum tasks have been implemented, from basic quantum optic experiments [1,4,5] to sophisticated quantum information processing such as Shor's algorithm [6], quantum walks [7,8], and boson sampling [9][10][11][12][13][14]. In the future, it is expected that such quantum functional circuits will be integrated on chip with other devices such as photon sources [15,16], functional circuits [17,18], buffers [19], and detectors [20][21][22][23], so that we can realize all optical quantum processors, as shown in Figure 1 [19].…”

“…Because of this small cross-section, together with the large nonlinear refractive index of silicon, we can observe an enhanced nonlinear coefficient γ (/W/m) [33] that is much larger than that of a silica waveguide. Several groups have already reported the generation of correlated [15] and entangled [16] photon pairs using an SWW.…”