High-rate photon pairs and sequential Time-Bin entanglement with Si₃N₄ microring resonators

Abstract

Integrated photonics is increasing in importance for compact, robust, and scalable enabling quantum technologies. This is particularly interesting for developing quantum communication networks, where resources need to be deployed in the field. We exploit photonic chip-based Si 3 N 4 ring microresonators to realise a photon pair source with low-loss, high-noise suppression and coincidence rates of 80×10 3 s −1 . A simple photonic noise characterisation technique is presented that distinguishes linear and nonlinear contributions useful for system design and optimisation. We then demonstrate an all-fibre 750 MHz clock-rate sequential Time-Bin entanglement scheme with raw interference visibilities > 98 %.

Broadband quadrature-squeezed vacuum and nonclassical photon number correlations from a nanophotonic device

“…Homodyne detection provides exquisite mode selectivity of the probed quantum state, whereas most photon counting schemes are limited in their ability to extract information from only a single well-defined field mode without incurring unacceptably high losses. For example, at the powers required to generate squeezing, one might be concerned that broadband spontaneous Raman scattering of the bright pump ( 32 ) (either in the chip or in the various fiber components through which the pump must propagate) might place unreasonable spectral filtering requirements on the signal and idler paths, adding losses that would destroy quantum correlations. In addition, as discussed in Introduction, any multimodedness of the light measured by a photon counting detection system will alter the measured statistics and corrupt the corresponding performance.…”

Integrated photon-pair sources with nonlinear optics

“…With SiN MRRs, time-bin/energy-time 171,173 and highdimensional frequency-bin 172 entangled states were also generated with a brightness of 150 MHz/nm/mW 171 . Thanks to the wider bandgap and ultra-low losses of SiN, time-energy entangled photon pairs were generated also in the visible range with a CAR as high as 3780 174 .…”

Coherent manipulation of graph states composed of finite-energy Gottesman-Kitaev-Preskill-encoded qubits

“…Quantum information is most commonly encoded in the photonic domain in the discrete, finite degrees of freedom of single photons such as their polarization or propagation paths, or transverse spatial modes [15,16], or frequency [17][18][19] or temporal modes [20,21], or time bins [22,23]. Deterministic generation of single photons forms the key challenge in realizing these encodings.…”