Photonic quantum computing has been dramatically scaled up recently by the promising approach of combining the continuous-variable" and time-multiplexing" schemes. We report on our recent development of time-multiplexed programmable continuous-variable photonic quantum computing, including a programmable loop-based quantum processor for single-mode multi-step Gaussian gates and a programmable time-multiplexed squeezed light source for initial state preparation. Our works pave the way to large-scale programmable continuous-variable quantum computing.
One of the leading approaches to large-scale quantum information processing (QIP) is the continuous-variable (CV) scheme based on time multiplexing (TM). As a fundamental building block for this approach, quantum light sources to sequentially produce time-multiplexed squeezed-light pulses are required; however, conventional CV TM experiments have used fixed light sources that can only output the squeezed pulses with the same squeezing levels and phases. We here demonstrate a programmable time-multiplexed squeezed light source that can generate sequential squeezed pulses with various squeezing levels and phases at a time interval below 100 ns. The generation pattern can be arbitrarily chosen by software without changing its hardware configuration. This is enabled by using a waveguide optical parametric amplifier and modulating its continuous pump light. Our light source will implement various large-scale CV QIP tasks.