High-Efficiency Plug-and-Play Source of Heralded Single Photons

Abstract

Reliable generation of single photons is of key importance for fundamental physical experiments and to demonstrate quantum technologies. Waveguide-based photon pair sources have shown great promise in this regard due to their large degree of spectral tunability, high generation rates and long photon coherence times. However, for such a source to have real world applications it needs to be efficiently integrated with fiber-optic networks. We answer this challenge by presenting an alignment-free source of photon pairs in the telecommunications band that maintains heralding efficiency > 50 % even after fiber pigtailing, photon separation, and pump suppression. The source combines this outstanding performance in heralding efficiency with a compact, stable, and easy-touse 'plug & play' package: one simply connects a laser to the input and detectors to the output and the source is ready to use. This high performance can be achieved even outside the lab without the need for alignment which makes the source extremely useful for any experiment or demonstration needing heralded single photons.

Fabrication limits of waveguides in nonlinear crystals and their impact on quantum optics applications

“…Ti:LN waveguides have been widely used for classical and quantum applications [5,6,[27][28][29][30][31][32]. They exhibit extremely low propagation losses (<0.1 dB cm −1 ), can guide both TE and TM polarization modes, possess high nonlinearity, allow on-chip manipulation of the light field via integrated beamsplitters and acousto-and electrooptical modulators and can be easily interfaced to fibre network via pigtailing [14].…”

“…Realizing nonlinear processes in integrated waveguides is fundamental in bringing quantum protocols and devices closer to every-day life [13]. Integrated nonlinear waveguides offer a few advantages over bulk nonlinear crystals, since they achieve a stronger nonlinear interaction by increasing the field confinement over longer lengths and can be interfaced more easily with fibre networks [14]. Moreover, they can be integrated along with other linear and nonlinear elements to generate and manipulate different quantum states of light [15][16][17][18].…”

Integrated transition edge sensors on titanium in-diffused lithium niobate waveguides

“…Titanium indi used waveguides in lithium niobate are surface-guiding and o er low-loss waveguiding in both polarization directions (TE and TM), across a broad frequency range, making them ideal for a range of quantum optical circuits. For example, integrated single-photon sources using parametric down conversion 3,4 can be combined with electro-optic modulators 5,6 and active or passive routing to enable a variety of applications in quantum optics 7 . In addition, low-loss ber pigtailing, by a aching single-mode bers directly to the waveguide end-faces ("bu -coupling"), enables high overall system e ciency 3 and compatibility with the existing communication network infrastructure.…”

Frequency-Domain Quantum Interference with Correlated Photons from an Integrated Microresonator

“…Cavity-enhanced spontaneous four-wave mixing (SFWM) in integrated microresonators produces frequency-entangled photon pairs with an effectively discrete joint spectral intensity [13][14][15][16][17]. A large number of such compact, identical sources can be integrated on a monolithic platform for the generation and manipulation of complex non-classical states of light [18][19][20][21]. Our demonstration establishes BS-FWM as a tool for selective, high-fidelity two-photon operations between frequency modes of integrated microresonators.…”