  Randomness is a very important resource for cryptography, algorithms, and
scientific simulations. Since all classical processes are considered to be
intrinsically deterministic, we must build quantum random number generators
which utilize quantum processes to generate true randomness. Quantum random
number generators have been realized in different quantum systems, including
quantum optical systems, and trapped ions. Here we present a proof-of-concept
random number generator based on a nuclear spin system for the first time. The
state preparation and measurements are performed with high-fidelity operations
in our system. The entropy of randomness in the experimental data is quantified
by two dimension witness certification protocols, which require no detailed
models to describe the experimental devices but only some general assumptions,
such as the limited dimensionality and the independence of the experimental
devices.
