Researchers at ETH Zurich have demonstrated a means of generating "perfect randomness" by using entangled superconducting qubits.

Creating true randomness is extremely difficult. Even the most sophisticated conventional random number generator can carry tiny biases. While in most everyday uses those biases are harmless, in cryptography — where the security of encrypted systems depends on unpredictability — even the most subtle pattern can become an exploitable weakness.

The team at ETH Zurich, led by physics professors Renato Renner and Andreas Wallraff, say they have shown how to overcome this flaw and create perfectly random numbers using quantum physics, a milestone they describe as the first certified realization of perfect randomness.

Traditional random-number generators often rely on physical processes such as photon behavior, but those systems can still be slightly skewed and exhibit a bias that causes certain numbers to appear more frequently than others. The ETH team's approach uses quantum entanglement to push randomness beyond that limit.