Quantum computers can in principle solve certain problems faster than classical computers. Despite substantial progress in the past decades, building quantum machines that can actually outperform classical computers for some specific tasks—a milestone termed as “quantum supremacy”—remained challenging. Boson sampling has been considered as a strong candidate to demonstrate the “quantum supremacy”.
The experimental challenge for realizing a large-scale boson sampling mainly lies in the lack of a perfect single-photon sources. In this talk, I will report two routes towards building boson sampling machines with many photons, which is also a first, necessary toward photonic quantum computing. In the first path, we developed SPDC two-photon source with simultaneously a collection efficiency of 97% and an indistinguishability of 96% between independent photons. With this, we demonstrate genuine entanglement of 12 photons.
In the second path, using a quantum dot-micropillar, we produced single photons with high purity (>99%), near-unity indistinguishability for >1000 photons, and high extraction efficiency—all combined in a single device compatibly and simultaneously. We build 3-, 4-, and 5-bosonsampling machines which runs >24,000 times faster than all the previous experiments, and for the first time reaches a complexity about 100 times faster than the first electronic computer (ENIAC) and transistorized computer (TRADIC). We hope to achieve 20-photon boson sampling in the near term.
Relevant papers can be found at http://staff.ustc.edu.cn/~cylu.