Phase-Programmable Gaussian Boson Sampling Using Stimulated Squeezed Light

We report phase-programmable Gaussian boson sampling (GBS) which produces up to 113 photon detection events out of a 144-mode photonic circuit. A new high-brightness and scalable quantum light source is developed, exploring the idea of stimulated emission of squeezed photons, which has simultaneously near-unity purity and efficiency. This GBS is programmable by tuning the phase of the input squeezed states. The obtained samples are efficiently validated by inferring from computationally friendly subsystems, which rules out hypotheses including distinguishable photons and thermal states. We show that our GBS experiment passes a nonclassicality test based on inequality constraints, and we reveal nontrivial genuine high-order correlations in the GBS samples, which are evidence of robustness against possible classical simulation schemes. This photonic quantum computer, Jiuzhang 2.0, yields a Hilbert space dimension up to similar to 1043, and a sampling rate similar to 1024 faster than using brute-force simulation on classical supercomputers.

Automated summary

Phase-programmable Gaussian boson sampling (GBS) is a new quantum technology that allows for high-purity and high-efficiency photon sampling through tuning the phase of squeezed input states. The experimental results demonstrate the capability of GBS to pass nonclassicality tests and exhibit nontrivial genuine high-order correlations, indicating robustness against classical simulation schemes.