Method and system for generating a random bit sample

A system for generating a random bit sample, the system comprising:

• a quantum tunneling barrier circuit having a quantum tunneling barrier incorporating an insulator sandwiched between two conductors, a current of charges tunneling from a first one of the two conductors to a second one of the two conductors and across the insulator, the current of the tunnelled charges having an instantaneous level varying randomly due to quantum tunneling fluctuations and forming a raw signal;
• a monitor configured to received said raw signal and to, from said raw signal, obtain a raw bit sample having a first bit number n, the first bit number n being an integer;
• and
• a randomness extractor configured to extract the randomness out of the raw bit sample into the random bit sample, the random bit sample having a second bit number m being smaller than the first bit number n, said extracting being based on calibration data comprising at least a quantum contribution value of said quantum tunneling fluctuations in said raw bit sample;
• and an external noise contribution value in said raw bit sample;
• wherein said extracting comprises determining said calibration data from variance data indicative of a variance of raw bit samples obtained from said quantum tunneling barrier as function of a voltage at which the quantum tunneling barrier is operated.