  Quantum random number generation is a key ingredient for quantum cryptography
and fundamental quantum optics and could advance Monte-Carlo simulations and
machine learning. An established generation scheme is based on single photons
impinging on a beam splitter. Here, we experimentally demonstrate quantum
random number generation solely based on the spontaneous emission process in
combination with the symmetric emission profile of a dipole aligned orthogonal
to the laboratory frame. The demonstration builds on defect centers in
hexagonal boron nitride and benefits from the ability to manipulate and align
the emission directionality. We prove the randomness in the correlated photon
detection events making use of the NIST randomness test suite and show that the
randomness remains for two independently emitting defect centers. The scheme
can be extended to random number generation by coherent single photons with
potential applications in solid-state based quantum communication at room
temperature.
