Single-System-Based Generation of Certified Randomness Using Leggett-Garg Inequality

We theoretically formulate and experimentally demonstrate a secure scheme for semi-device-independent quantum random number generation by utilizing Leggett-Garg inequality violations, within a loophole-free photonic architecture. The quantification of the generated randomness is rigorously estimated by analytical as well as numerical approaches, both of which are in perfect agreement. We securely generate 919 118 truly unpredictable bits at a rate of 3865 bits/sec. This opens up an unexplored avenue toward an empirically convenient class of reliable random number generators harnessing the quantumness of single systems.