Real-time Quantum Random Number Generator on a Chip Achieves Constant Output

True random number generators are essential for secure communication and a variety of technological applications, and scientists increasingly focus on creating compact, efficient devices. Guan-Ru Qiao, Bing Bai, and Zi-Xuan Weng, along with colleagues at their institutions, now demonstrate a fully functional quantum random number generator on a chip, representing a significant step towards miniaturised, practical quantum technology. The team achieves this breakthrough by harnessing the inherent randomness of vacuum-state fluctuations within a hybrid photonic circuit, integrating light-based and electrical components into a robust, compact package. This innovative chip delivers a constant stream of random numbers at a rate of 5. 2 Mbps, even across a wide industrial temperature range, paving the way for secure and reliable applications in diverse fields.

6mm x 7. 8mm, harnessing vacuum-state fluctuations as its source of randomness. The device’s core utilizes a hybrid photonic integration scheme with a silicon dioxide (SiO2) waveguide, fabricated using established planar lightwave circuit technology. This process involves depositing a germanium-doped SiO2 core layer onto a SiO2 substrate and cladding, followed by precise etching to define the Y-splitter waveguide geometry, creating the necessary contrast for guiding light waves.

Researchers optimized the splitting ratio of the waveguide through iterative refinement, ensuring balanced signal distribution. The study pioneered a system-in-package (SiP) technology to integrate both optical and electronic components onto a single chip. A Kovar alloy heat sink provides a stable foundation for mounting the Y-splitter waveguide, a distributed feedback laser diode (LD) emitting at 1550nm, a lens for coupling light into the waveguide, a transimpedance amplifier (TIA), and a photodiode (PD) array. The LD, operating efficiently, is precisely aligned with the waveguide via the lens, ensuring maximum light injection.

The PD array, with a small active area and high responsivity at 1550nm, functions as a homodyne detector, while the TIA amplifies the weak electrical signals from the PDs. Scientists employed a stacked configuration, placing the hybrid photonic entropy source on top of a printed circuit board (PCB) containing a microcontroller unit (MCU) and operational amplifier (OPA), optimizing space within the QRNG chip. Calibration procedures involved an external reference light source and current monitoring of the LD and PDs, ensuring balanced signal distribution across both detection channels. Researchers meticulously adjusted the PD array and lens position to maximize the optical response and achieve consistent dual-channel performance, ultimately realizing a compact and robust QRNG capable of delivering a constant real-time output rate of 5. 2 Mbps across an industrial temperature range of -40°C to 85°C.

Compact Chip Generates True Quantum Randomness

Scientists have achieved a significant breakthrough in quantum random number generation with the development of a fully functional chip based on vacuum-state fluctuations. This innovative device, measuring just 16. 6mm x 7. 8mm, represents a crucial step towards miniaturized and practical quantum random number generators, essential for secure communication and advanced computation. The core of the system is a quantum entropy source, realized through hybrid photonic integration utilizing a silicon dioxide waveguide, which generates the raw random numbers underpinning the entire process.

The research team successfully integrated both photonic and electrical components into a compact ceramic package using system-in-package technology, demonstrating a robust and efficient design. A microcontroller unit acquires the raw data generated by the entropy source and processes it, outputting the final random numbers via a serial peripheral interface. Characterization of the QRNG chip reveals a constant, real-time output rate of 5. 2 Mbps, a critical performance metric for practical applications. Importantly, this output rate remains stable across a wide industrial temperature range, from -40°C to 85°C, ensuring reliable operation in diverse environments.

The quantum entropy source leverages the inherent randomness of vacuum-state fluctuations, measured using a Y-splitter waveguide, to generate truly unpredictable random numbers. Mathematical analysis confirms the equivalence of this Y-splitter approach to traditional beam splitter designs, validating the effectiveness of this novel implementation. The team demonstrated that the system’s randomness arises from the quadrature measurement of these vacuum-state fluctuations, guaranteed by the fundamental principles of quantum mechanics. This breakthrough delivers a compact, high-performance quantum random number generator, paving the way for enhanced security and advanced computational capabilities in a wide range of applications.

Robust Quantum Randomness Across Industrial Temperatures

Researchers have successfully developed a fully functional quantum random number generator (QRNG) chip, achieving a constant output rate of 5. 2 Mbps across a wide industrial temperature range, from -40°C to 85°C. This compact device, measuring just 16. 6mm x 7. 8mm, generates truly random numbers based on the fundamental principles of quantum physics, specifically vacuum-state fluctuations.

The team implemented a hybrid photonic integration approach, utilising a silicon dioxide waveguide to create the entropy source, and integrated both photonic and electronic components within a compact ceramic package. The resulting chip acquires raw data, processes it to enhance uniformity and unpredictability, and outputs final random numbers via a serial peripheral interface. Rigorous testing confirms the high quality of the generated numbers, with statistical tests demonstrating both randomness and statistical independence. This achievement represents a significant step towards practical, cost-effective, and low-power quantum random number generation suitable for a broad range of applications.