Ying Wang, Carlos F. D. Faurby, Fabian Ruf, Patrik I. Sund, Kasper H. Nielsen, Nicolas Volet, Martijn J. R. Heck, Nikolai Bart, Andreas D. Wieck, Arne Ludwig, Leonardo Midolo, Stefano Paesani, Peter Lodahl
Feb 13, 2023·quant-ph·PDF We develop a quantum photonic platform that interconnects a high-quality quantum dot single-photon source and a low-loss photonic integrated circuit made in silicon nitride. The platform is characterized and programmed to demonstrate various multiphoton applications, including bosonic suppression laws and photonic entanglement generation. The results show a promising technological route forward to scale-up photonic quantum hardware.
Kasper H. Nielsen, Etienne Corminboeuf, Benedikt Tissot, Love A. Pettersson, Sven Scholz, Arne Ludwig, Leonardo Midolo, Anders S. Sørensen, Peter Lodahl, Ying Wang, Stefano Paesani
Apr 23, 2026·quant-ph·PDF High-quality photonic Bell state measurements (BSMs) enable scalable universal quantum computing and long distance quantum communication. However, when implemented with linear optics, BSMs are fundamentally probabilistic, introducing substantial hardware overheads and limiting noise tolerance in photonic quantum computing architectures. Nonlinear interactions at the single-photon level can overcome these limitations by enabling near-deterministic photon-photon gates. Here, we demonstrate a passive photon-sorting circuit based on the induced nonlinearity arising from photon scattering in a solid-state quantum emitter. The scattering is implemented in a directional waveguide-emitter coupling interface and embedded on-chip into a linear optical circuit, through which we demonstrate sorting of one- and two-photon components with a success probability of 62%. We find that the current system can enable BSMs with a 57% post-selected success probability without ancillary photons, exceeding the linear-optical limit of 50%, and can be readily improved to >65% with design optimisations.
Kasper H. Nielsen, Ying Wang, Edward Deacon, Patrik I. Sund, Zhe Liu, Sven Scholz, Andreas D. Wieck, Arne Ludwig, Leonardo Midolo, Anders S. Sørensen, Stefano Paesani, Peter Lodahl
May 28, 2024·quant-ph·PDF The lack of interactions between single photons prohibits direct nonlinear operations in quantum optical circuits, representing a central obstacle in photonic quantum technologies. Here, we demonstrate multi-mode nonlinear photonic circuits where both linear and direct nonlinear operations can be programmed with high precision at the single-photon level. Deterministic nonlinear interaction is realized with a tunable quantum dot embedded in a nanophotonic waveguide mediating interactions between individual photons within a temporal linear optical interferometer. We demonstrate the capability to reprogram the nonlinear photonic circuits and implement protocols where strong nonlinearities are required, in particular for quantum simulation of anharmonic molecular dynamics, thereby showcasing the new key functionalities enabled by our technology.