In our modern interconnected society, random bit generators (RBGs) play a crucial role in the security of various services and cutting-edge technologies like secure communication, blockchain, and quantum key distribution. With the growing emphasis on safeguarding digital information, the reliance on pseudorandom algorithms for generating random bits has shifted to using physical entropy sources.
According to Shannon's theorem, achieving the highest level of security requires matching the bit rate of true RBGs with that of communication systems. To address this, researchers have extensively studied the use of optical chaos for generating wideband entropy sources, overcoming the limitations of traditional electronic RBGs.
However, current physical RBGs face challenges in terms of speed and scalability. As chaotic sources typically produce only one stream of non-correlated intensity fluctuation, the generation of multiple random bit streams is limited. Moreover, the response speed of entropy extractors like analog-to-digital converters (ADCs) poses a challenge to continuously improve the bit generation rate to meet the demands of advanced communication systems.
A team of scientists, led by
By using a modulation-instability-driven chaotic comb in the MRR, hundreds of independent and unbiased random bit streams can be generated simultaneously. A proof-of-concept experiment showed that this approach could achieve a generation rate of 320 Gb/s per channel, resulting in a total bit rate of 2.24 Tb/s using only seven channels. This bit rate can be further increased by increasing the number of comb lines used.
Compared to existing RBG techniques, this method offers exceptional scalability and efficiency with a single MRR. It not only produces multiple independent random bit streams but also significantly enhances the bit generation rate in a single channel. Additionally, this method is simple, can be easily generalized, and does not require special materials. The chaotic microcomb used in the experiment was produced using a CMOS-compatible, high-index, doped silica-glass MRR.
Furthermore, the small size of the MRR and simplified random bit extraction process make this method suitable for chip-scale parallel RBGs. With its ultrahigh speed and potential for miniaturization, this approach has promising applications in secure communication and other related fields.