Measurement-Incompatibility Constraints for Maximal Randomness

Abstract: We propose a general method to certify maximal quantum randomness without relying on Bell inequalities, applicable to arbitrary multi-user scenarios. By analyzing probability distributions directly, we identify a class of quantum states and projective measurements that achieve maximal randomness. We establish a constraint among users' measurement incompatibilities. Surprisingly, we find that sufficiently big incompatibility on one party's measurements relaxes the requirements on the others', which can even be arbitrarily weak. The method is demonstrated in both bipartite and tripartite systems, providing a versatile framework for device-independent randomness generation in quantum networks.