Massively parallel ultrafast random bit generation with a chip-scale laser

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Science  26 Feb 2021:
Vol. 371, Issue 6532, pp. 948-952
DOI: 10.1126/science.abc2666

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Laser-based generation of random numbers

The security of our digital networks is underpinned by the ability to generate streams of random numbers or bits. As networks expand in an ever-connected way, the challenge is to increase the generation rate of the random numbers to keep pace with demand. Kim et al. designed a chip-scale laser diode that generates random bits at an ultrahigh rate (see the Perspective by Fischer and Gauthier). By tailoring the geometry of the cavity, they were able to exploit the spatiotemporal interference of many lasing modes to generate picosecond-scale emission intensity fluctuations in space and time, producing ultrafast random bit streams in parallel. Such a device will find a wide range of applications requiring an ultrafast, compact, robust, and energy-efficient random bit generator.

Science, this issue p. 948; see also p. 889


Random numbers are widely used for information security, cryptography, stochastic modeling, and quantum simulations. Key technical challenges for physical random number generation are speed and scalability. We demonstrate a method for ultrafast generation of hundreds of random bit streams in parallel with a single laser diode. Spatiotemporal interference of many lasing modes in a specially designed cavity is introduced as a scheme for greatly accelerated random bit generation. Spontaneous emission, caused by quantum fluctuations, produces stochastic noise that makes the bit streams unpredictable. We achieve a total bit rate of 250 terabits per second with off-line postprocessing, which is more than two orders of magnitude higher than the current postprocessing record. Our approach is robust, compact, and energy-efficient, with potential applications in secure communication and high-performance computation.

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