Quantum random-number generators (QRNGs) produce true random numbers based on the inherent randomness of quantum theory, rendering them a foundational segment of quantum cryptography. Distinguished from trusted-device QRNGs, whose security depends on characterized devices, semi-device-independent (semi-DI) QRNGs permit partial devices to be defective or even maliciously manipulated, achieving a good trade-off between generation rate and security. In this paper, we propose a semi-DI QRNG that resists general attacks while accounting for finite-size effects. The protocol requires no rigorous characterization of the source and measurement devices other than limiting the energy of the emitted states, significantly reducing the demand on practical QRNG systems. Leveraging the tight Kato’s inequality for correlated variables, we show that our protocol generates more randomness than it consumes. Furthermore, we demonstrate the scheme using a continuous-variable system with ternary inputs of states. Heterodyne detection is employed to enable phase compensation through data postprocessing, alleviating the stringent requirement on system stability. The system operates at 100 MHz, achieving a net random-number generation rate of 1.165 Mbps at $5.3\times {10}^9$ rounds. Our work offers a promising approach to achieving both robust security and a high generation rate with a simple experimental setup.

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• Entropy production
• Optical quantum information processing
• Quantum cryptography
• Quantum fluctuations & noise
• Quantum information processing with continuous variables
• Quantum protocols
• Devices
• Homodyne & heterodyne detection