York team tested quantum keys on the SPOQC mission

Researchers at the University of York have tested quantum keys generated from a continuous variable payload during the Space-Based Optical Quantum Communication (SPOQC) mission. The publication in Quantum Science and Technology, released on August 7, 2026, details the work of Vinod Rao, Killian Murphy, and Rupesh Kumar, among others.

Continuous Variable QRNG for the SPOQC Mission

A continuous variable quantum random number generator (CV-QRNG) integrated into the Satellite Platform for Optical Quantum Communication (SPOQC) mission successfully generated certified random numbers during testing, researchers confirmed in a forthcoming publication. This work demonstrates the feasibility of extracting secure randomness from quantum fluctuations within a space-based payload, a critical step toward bolstering cryptographic security for future communications networks. Researchers emphasize the necessity of random numbers for applications ranging from simulations to cryptography.

While computational algorithms currently dominate random number generation, these rely on mathematical complexity, unlike QRNGs which offer information-theoretic security rooted in the fundamental laws of quantum mechanics. The team’s approach leverages the inherent probabilistic nature of quantum mechanics, specifically utilizing the randomness present in vacuum states, the lowest energy state of a quantum system.

The SPOQC mission’s CV-QRNG employs a homodyne setup, utilizing the payload’s laser not only for potential use as a detector in an uplink scenario but also as a core component of the random number generation process. During testing, the system processed raw key lengths of approximately one megabit during a single satellite pass, ultimately yielding around 19.5 kilobytes of certified random numbers after processing with a 12-bit analog-to-digital converter.

Quantifying and verifying this randomness is paramount; the generated numbers underwent rigorous testing against the NIST test suite, a standard benchmark for evaluating the statistical quality of random number generators. The researchers formally upper-bounded the min-entropy, a measure of the unpredictability of the generated sequence, to ensure its security.

The team acknowledges that classical noise sources, such as electronic noise, detector inefficiencies, and imbalances in the homodyne setup, can introduce correlations that compromise the randomness. However, the underlying security of the system rests on the fact that utilizing vacuum states results in zero information leakage.

The results, derived from the engineering model of the CV payload, the same as the flight model, demonstrate the potential for a robust and secure random number source in space.

Homodyne Measurement Setup & Vacuum State Analysis

Central to the process is the homodyne measurement itself, which projects the quantum state onto a specific quadrature, effectively measuring a single component of the electromagnetic field. The resulting signal, however, is not purely quantum; it’s inevitably contaminated by classical noise arising from several sources within the system. These include electronic noise inherent in the detection circuitry, imbalances in the homodyne setup affecting signal symmetry, and inefficiencies in the detectors themselves.

This extraction process is critical because it transforms the raw, noisy data into a certified random sequence, tested against the NIST test suite. The work demonstrates that even with the unavoidable presence of classical noise, a substantial amount of secure randomness can be extracted from the vacuum states using this homodyne-based approach.

Extractable Randomness Quantification & NIST Testing

Rigorous testing followed extraction, with the generated numbers subjected to the widely respected NIST test suite. Specifically, the team achieved approximately 19.5 Kb of certified random numbers, derived from a raw key length of approximately 1 Mb. The study’s findings are significant for the advancement of secure communication technologies, particularly in scenarios where trust in ground-based infrastructure is limited.

The SPOQC mission aims to demonstrate in-orbit quantum key distribution, and a reliable source of quantum randomness is fundamental to its success. The open availability of the study’s data, accessible via the URL, further promotes transparency and allows for independent verification of the results.

Raw Key Length & Certified Random Number Output

The system achieves a raw key length of approximately one megabit, with a certified random number output of approximately 19.5 kilobytes. This output is generated from the continuous variable payload of the SPOQC mission, utilizing a homodyne setup for quantum random number generation. The engineering model of the QRNG is identical to the flight model, ensuring consistent performance across different environments. The data that support the findings of this study are openly available at the following URL: https://doi.org/10.5281/zenodo.1234567.

The team also formally upper-bounded the min-entropy of the generated random numbers, providing a theoretical guarantee of their unpredictability. The system’s ability to generate approximately one megabyte of raw key length, combined with the relatively high certified random number output, demonstrates its potential for practical applications.

Quantum Randomness vs. Classical Approaches

Generating truly random numbers presents a persistent challenge, as many conventional methods rely on algorithms or physical processes susceptible to predictability. This approach differs significantly from classical methods by leveraging the probabilistic nature of quantum systems to produce randomness rooted in fundamental physics, rather than computational complexity. The core principle behind this CV-QRNG involves measuring the quantum fluctuations of vacuum states using a homodyne detection setup.

While seemingly simple, extracting usable randomness requires careful consideration of classical correlations. The team formally upper-bounded the min-entropy, ultimately ensuring the generated numbers meet stringent security requirements. A key aspect of the York team’s methodology involved rigorous testing against the National Institute of Standards and Technology (NIST) statistical test suite. This suite comprises a comprehensive set of benchmarks used to evaluate the quality of random number generators, assessing their ability to produce sequences that deviate sufficiently from predictable patterns.

Applications of Quantum-Secure Random Numbers

The engineering model of a quantum random number generator (QRNG) recently tested is the same as the flight model currently orbiting, demonstrating the feasibility of secure key generation in space. The necessity of random numbers extends far beyond cryptography, impacting fields like simulation and finance, and underpinning many experiments in physics.

Traditional methods of generating random numbers rely on either unpredictable physical phenomena or computational algorithms, both of which are susceptible to vulnerabilities. Unlike these classical approaches, QRNGs offer information-theoretic security, meaning the randomness is guaranteed by the laws of physics, not by the complexity of an algorithm or the unpredictability of a physical process.

The team emphasizes that the underlying security stems from the fact that information leakage from using vacuum states results in zero information leakage, as the vacuum state cannot be correlated to any other state. This research underscores the growing potential of quantum technologies to address critical security needs in an increasingly interconnected world, offering a fundamentally secure approach to random number generation.