Lutfi Arif Ngah

Hybrid photonic circuit for multiplexed heralded single photons

A key resource for quantum optics experiments is an on-demand source of single and multiple photon states at telecommunication wavelengths. This letter presents a heralded single photon source based on a hybrid technology approach, combining high efficiency periodically poled lithium niobate waveguides, low-loss laser inscribed circuits, and fast (>1 MHz) fibre coupled electro-optic switches. Hybrid interfacing different platforms is a promising route to exploiting the advantages of existing technology and has permitted the demonstration of the multiplexing of four identical sources of single photons to one output. Since this is an integrated technology, it provides scalability and can immediately leverage any improvements in transmission, detection and photon production efficiencies.

Polarization entangled photon-pair source based on quantum nonlinear photonics and interferometry

We present a versatile, high-brightness, guided-wave source of polarization entangled photons, emitted at a tele-com wavelength. Photon-pairs are generated using an integrated type-0 nonlinear waveguide, and subsequently prepared in a polarization entangled state via a stabilized fiber interferometer. We show that the single photon emission wavelength can be tuned over more than 50 nm, whereas the single photon spectral bandwidth can be chosen at will over more than five orders of magnitude (from 25 MHz to 4 THz). Moreover, by performing entanglement analysis, we demonstrate a high degree of control of the quantum state via the violation of the Bell inequalities by more than 40 standard deviations. This makes this scheme suitable for a wide range of quantum optics experiments, ranging from fundamental research to quantum information applications. We report on details of the setup, as well as on the characterization of all included components, previously outlined in F. Kaiser et al. (2013 Laser Phys. Lett. 10, 045202).

Toward Continuous-Wave Regime Teleportation for Light Matter Quantum Relay Stations

We report a teleportation experiment involving narrowband entangled photons at 1560 nm and qubit photons at 795 nm emulated by faint laser pulses. A nonlinear difference frequency generation stage converts the 795-nm photons to 1560 nm in order to enable interference with one photon out of the pairs, i.e., at the same wavelength. The spectral bandwidth of all involved photons is of about 25 MHz, which is close to the emission bandwidth of emissive quantum memory devices, notably those based on ensembles of cold atoms and rare earth ions. This opens the route toward the realization of hybrid quantum nodes, i.e., combining quantum memories and entanglement-based quantum relays exploiting either a synchronized (pulsed) or a asynchronous (continuous-wave) scenario.

All-optical synchronization for quantum communication networks

We report an all-optical realisation of a quantum relay experiment at a telecom wavelength. The main idea relies on utilizing a picosecond 2.5 GHz repetition rate telecom laser as a master clock to allow, thanks to dedicated distribution channels, the generation of synchronized entangled pairs of photons at remote locations. This is a necessary condition for achieving a reliable quantum relay function over a significant distance. We report a two-photon interference visibility at the relay station greater than 99%, validating our synchronization scheme at optical table scale, and paving the way for an extend of the communication distance.

Towards high repetition rate operational quantum relay at telecom wavelength

Quantum entanglement, besides being a theoretical ground in quantum physics, is now considered as a key resource for the implementations of many complex quantum information science (QIS) protocols. One of the most investigated QIS protocols for long-distance quantum communication, involving entanglement as a genuine resource, is the entanglement swapping in quantum relay (QR) configuration. Alas, the quality of a QR is heavily affected by synchronization issues between remote entangled photon pair sources. In this paper, we present an all-optical, high repetition rate synchronization technique in picosecond regime, and demonstrate the realization of ultra-fast photon pair sources based on high-performance telecom components and nonlinear optics.

Hybrid integration for spatially-multiplexed single-photon generation

We discuss the hybrid integration of multiple components for the production of telecom band single photon sources. We implement four, on-chip, waveguide channels capable of producing four spatially separated collinear pairs of single photons. Using laser inscribed waveguide circuits and point-by-point bre Bragg gratings (FBG), we interface, separate and lter generated photon pairs. We propose using fast switches to actively route multiple heralded single photons to a single output producing an enhanced rate while maintaining a xed noise level.

Ultra-fast photon pair sources for long-distance quantum communication

We report on the realization of ultra-fast photon pair sources for long-distance quantum relays. Our sources are capable to deliver high-quality single photon pairs at high repetition rate, guaranteeing efficient operational condition for intended protocol.

Polarization entanglement engineering at telecom wavelengths

We report an efficient polarization entanglement engineering scheme based on a stabilized birefringent delay line. The scheme is capable of handling ultra narrowband photons making it compatible for multiplexing and quantum memory based applications.