contextuality

We experimentally realize a quantum random number generator (QRNG) with randomness of each generated number certified by the Kochen-Specker theorem. Employing this novel certification scheme eliminates the necessity for input seed random numbers and lifts the non-locality requirement for the certified QRNG. Implementation on the base of superconducting qubits allows achieving a bit rate of 25 kBit/s, two orders of magnitude higher than previously reported certified QRNGs. These improvements make our result a major step towards realization a practical certified quantum QRNG with implications for digital security and modelling algorithms.

Contextuality is one of the most fundamental properties of quantum mechanics, distinguishing it from classical physics without a need for nonlocality or entanglement. It is also a critical resource for exponential speedup in universal surface-code quantum computing. Our result is the first experiment violating a noncontextuality inequality with an indivisible system where entanglement cannot be defined which also addresses all known major loopholes, such as the detection, compatibility and individual-existence loopholes. Violating noncontextuality with superconducting circuits, a leading candidate for implementing surface-code quantum computing, comprises an important conceptual milestone in demonstrating their suitability for quantum technological applications.