Hong–Ou–Mandel interference between independent III–V on silicon waveguide integrated lasers

Abstract

The versatility of silicon photonic integrated circuits has led to a widespread usage of this platform for quantum information based applications, including Quantum Key Distribution (QKD). However, the integration of simple high repetition rate photon sources is yet to be achieved. The use of weak-coherent pulses (WCPs) could represent a viable solution. For example, Measurement Device Independent QKD (MDI-QKD) envisions the use of WCPs to distill a secret key immune to detector side channel attacks at large distances. Thus, the integration of III-V lasers on silicon waveguides is an interesting prospect for quantum photonics. Here, we report the experimental observation of Hong-Ou-Mandel interference with 46 ± 2% visibility between WCPs generated by two independent III-V on silicon waveguide integrated lasers. This quantum interference effect is at the heart of many applications, including MDI-QKD. Our work represents a substantial first step towards an implementation of MDI-QKD fully integrated in silicon, and could be beneficial for other applications such as standard QKD and novel quantum communication protocols.

Boosting the secret key rate in a shared quantum and classical fibre communication system

“…This can be achieved using either conventional wavelength and space multiplexing technology in fibre or photonic integration, since several devices can be integrated onto the same chip. Fast and reliable photonic integrated circuits are already commercially available for classical communications, while quantum integrated photonics is a rapidly growing field [20,30,[49][50][51][52][53]. At the same time, to achieve a very high rate for quantum communication, SNSPDs or fast gated InGaAs single photon detectors are needed.…”

Integrated photonic quantum technologies

“…A few exciting technical challenges need to be tackled towards full integrations, such as how to manipulate photons at cryogenic temperature required for the detector operations. Nevertheless, fully integrated QKD chips are readily achievable in the InP [37,70] and Si/III-V platforms [71], promising miniaturized, low-costs devices allow for both quantum and classical communications.…”

The Quantum Regime Operation of Beam Splitters and Interference Filters

“…where χ (1) is the real part of the first-order susceptibility of the dielectric medium. This interaction will modify the complex field amplitude s n , j ( j = 1 , 2) of two co-propagating and overlapping optical beams of the same frequency, identifiable by their respective optical waveguides ( j = 1 , 2) .…”

“…ECENT developments in the integration of photonic devices for quantum information processing [1][2] are characterized by their capability to generate two-photon destructive interference for temporally overlapping indistinguishable photons, which is commonly known as the Hong-Ou-Mandel dip [3]. The reduction in the counting rate of coincident detection of photons at two spatially separated photodetectors is explained by opposite sign amplitudes for the probabilities of detecting each photon pair after having been reflected or transmitted by a beam splitter.…”

“…where ̂ is the electric dipole operator raising the atomic electron from one level to the next, and ̂ is the photon annihilation operator, with ̂ † its conjugate operator, the photon creation operator. The optically linear susceptibility χ (1) is included in the spatial coupling coefficient κ. The absorption of one photon through quantum Rayleigh conversion leads to the disappearance of an entangled state, that is:…”