Real-time vacuum-state quantum random-number generator on a chip

Quantum random-number generators (QRNGs) produce true random numbers, which are guaranteed by the fundamental principles of quantum physics. Miniaturization of QRNGs is crucial for a wide range of communication and cryptography applications. Here, we first report a fully functional QRNG chip based on vacuum-state fluctuations, with dimensions of $16.6\ifmmode\times\else\texttimes\fi{}7.8\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}$. The quantum entropy source, which is achieved via hybrid photonic integration with an ${\mathrm{Si}\mathrm{O}}_{2}$ waveguide, generates raw quantum random numbers. The hybrid photonic and electrical components are assembled into a compact ceramic package using system-in-package technology. A microcontroller unit acquires the raw data and outputs the processed quantum random numbers via a serial peripheral interface. According to the characterization results, the QRNG chip achieves a constant real-time output rate of 5.2 Mbps across the industrial temperature range of $\ensuremath{-}40$ to $85{\phantom{\rule{0.1em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$, making it suitable for practical applications.