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Researchers have developed a chip-based quantum random number generator that provides high-speed, high-quality operation on a miniaturized platform. This advance could help move quantum random number generators closer to being built directly into everyday devices, where they could strengthen security without sacrificing speed.

True randomness is essential for secure online banking, private messaging, and protecting sensitive data from hackers, and the rising need for stronger digital protection is driving fast-growing demand for high-quality random numbers generated at high speeds.

"The quantum properties of light make it possible to produce numbers that are truly random, unlike the numbers generated by computer algorithms, which only imitate randomness," said research team leader Raymond Smith from Toshiba's Cambridge Research Laboratory in the United Kingdom. "However, making this technology practical for real-world use requires the optical components that create these quantum effects to be as small as possible so they can fit inside other systems."

In the journal Optica Quantum, the researchers a new quantum random number generator design that can recover the quantum signal even when it's buried in noise, which has been challenging to accomplish with chip-integrated devices. The new device can generate unpredictable random numbers at a rate of 3 gigabits per second, fast enough to support the security needs of large-scale data centers.

"A major application of random number generators is in protecting sensitive data and communications using encryption keys," said Smith. "Our technology can generate those keys at high speed and with strong security guarantees. High-speed random numbers are also critical for scientific simulations and artificial intelligence and for ensuring fairness in applications like online gaming or digital lotteries."

Suppressing noise

Integrated photonics—which uses tiny optical circuits on a chip to generate, guide, and manipulate light—makes it possible to shrink complex optical setups down to just a few millimeters. However, these small systems are more sensitive to external disturbances such as electronic noise, which can ruin the quality of the quantum random numbers. For this reason, recovering true quantum randomness typically requires complex filtering procedures to clean the numbers, but these extra steps significantly reduce the generation rate.

To overcome these challenges, the researchers developed a quantum random number generator that boosts weak signals with an optical amplifier and uses a second photodiode to help suppress crosstalk and any other optical or electrical noise.

"Thanks to its built-in noise-rejection features, the photonic integrated circuit produces a much cleaner signal from the start, so it relies far less on heavy post-processing," said Smith. "This means we can keep the benefits of a miniaturized platform while still generating truly random numbers at high speed."

Robust random number generation

To test the new design, the researchers began by measuring the optical performance of the chip-based quantum random number generator in isolation. They found that the circuit behaved as expected, with the on-chip optical amplifier boosting the quantum signal.

They then packaged the chip and mounted it on a printed circuit board so that it could operate alongside high-speed electronics. Once the chip was no longer isolated, they observed electronic crosstalk, but their dual-photodiode design helped minimize this interference. In addition to generating random numbers at 3 Gbps, the system ran continuously for 24 hours, confirming excellent stability—a benefit of using a single laser to maximize interference visibility.

Next, the researchers plan to increase the level of integration between the optical and electronic parts. "Our goal is to add more electronic functionality directly alongside the photonic chip, so the generator becomes as close as possible to a compact, standalone device," said Smith. "This would make it easier to deploy in real-world systems and move it closer to commercial viability."