We experimentally demonstrate a high-entropy source based on the intensity fluctuation in a femtosecond laser. The setup successfully passes statistical tests without any post-processing. The generator can be potentially used for quantum communication and cryptography.
True random numbers with high security originate from non-deterministic physical processes. Random laser with random feedback arising from multiple elastic scattering in a highly disordered structure is an ideal physical entropy source theoretically. In this work, a secure optical ultrafast random number generator based on random laser spectra was demonstrated. Unlike the usual method of recording laser intensity over time, the random laser spectrum under each pump pulse was recorded and converted into random numbers through post-processing. Approaches in three different dimensions—space, spectrum and time were used to increase the rate of random number generation. The randomness of resulting random bit streams was verified by the NIST statistics tests. Experimental results showed that an instantaneous bit rate of 810 terabits per second with off-line post-processing could be theoretically reached with an ideal experimental condition. This novel technique has big advantages in secure communications and promises to further increase the speed of random number generators to the lever of petabits per second or even higher.
True randomness is critical to secure communication in both quantum and classical regimes. We propose an approach of true random number generation based on the intrinsic randomness of spontaneous emission. In this approach, a method of random bit extraction was employed to extract true random bits simultaneously as the measurement of the physical entropy source. The random bits generated by the true random number generators have been statistically verified to be bias-free and mutually independent. With the current experimental setup, 7 random bits can be generated in parallel at a rate up to 40 GHz.
A simple novel method for random number generation is presented, based on a random Raman fiber laser. This laser is built in a half-open cavity scheme, closed on one side by a narrow-linewidth 100 mm fiber Bragg grating. The interaction between the randomly excited lasing modes of this laser, in addition to nonlinear effects such as modulation instability, allow the generation of random bits at rates of up to 540 Gbps with minimal post processing. Evaluation of the resulting bit streams' randomness by the NIST statistical test suite highlights the importance of evaluating the physical entropy content, as bit sequences generated by this random laser pass all the statistical tests with a significance level of 0.01, despite being generated at more than twice the theoretical entropy generation speed.
Random numbers are essential for our modern information based society e.g. in cryptography. Unlike frequently used pseudo-random generators, physical random number generators do not depend on complex algorithms but rather on a physical process to provide true randomness. Quantum random number generators (QRNG) do rely on a process, which can be described by a probabilistic theory only, even in principle. Here we present a conceptually simple implementation, which offers a 100% efficiency of producing a random bit upon a request and simultaneously exhibits an ultra low latency. A careful technical and statistical analysis demonstrates its robustness against imperfections of the actual implemented technology and enables to quickly estimate randomness of very long sequences. Generated random numbers pass standard statistical tests without any post-processing. The setup described, as well as the theory presented here, demonstrate the maturity and overall understanding of the technology.
Lasers are recently being used more frequently in random number generators. The world record in random number generation was broken by the help of lasers. The world's fastest quantum random number generators utilize lasers to tap into the random fluctuations in order to extract true random bit sequences. We investigate a system based on a Nd:YAG laser that potentially generates true random bits at Gbit/s rates. As photonic on chip technologies progress we foresee laser based high speed random number generators integrated on chips. Such a photonic chip will create a revolution in the technology of security devices that employ quantum cryptography techniques for secure communication.