Synopsis: The fast and the random

The fastest known random number generator based on a physical process comes from intensity fluctuations in the light from a chaotic laser.
Synopsis figure

Message encryption, Monte Carlo simulations, and electronic gambling machines all rely on random number generators. With a computer algorithm, it is only possible to generate numbers in a pseudorandom way, since once one figures out the algorithm itself, the sequence of numbers can be known. For applications that require higher security, means of generating true, or nondeterministic, random numbers become necessary.

The intensity fluctuation in light from a chaotic laser, made chaotic by external optical feedback, has an unpredictable output, which approximately repeats itself at the round trip time of the external cavity. If this quasiperiodicity can be eliminated, the signal can be used to rapidly generate sequences of nondeterministic random bits. In a paper appearing in Physical Review Letters, Igor Reidler, Yaara Aviad, Michael Rosenbluh, and Ido Kanter from the Bar-Ilan University in Israel use a simple edge-emitting semiconductor laser to create a chaotic signal with a broad frequency spectrum and short, spiking intensity fluctuations. Reidler et al. sample the output laser intensity at a rate of 2.5GHz and store the measured value of the signal as 8bits, which they subtract from the previous value, and then truncate to obtain a random bit string. The differentiation and truncation eliminate the quasiperiodicity of the optical signal and the concatenated bit strings stream out at a rate of 12.5Gbits/s.

The generated stream passes the NIST and Diehard tests for randomness and is currently the fastest random number generator based on a physical process. – Sonja Grondalski


Announcements

More Announcements »

Subject Areas

OpticsNonlinear Dynamics

Previous Synopsis

Mesoscopics

Artificial graphene

Read More »

Next Synopsis

Atomic and Molecular Physics

Making monopoles

Read More »

Related Articles

Synopsis: Starting Fluid for Laser Fusion
Energy Research

Synopsis: Starting Fluid for Laser Fusion

A laser-based fusion experiment demonstrates that liquid fuel capsules could rectify problems encountered with ice-based fuel capsules. Read More »

Synopsis: Explaining Aftershock Clustering
Geophysics

Synopsis: Explaining Aftershock Clustering

A study of bursting phenomena like earthquakes suggests that events appear to cluster in time because of the way that small events like aftershocks are identified. Read More »

Synopsis: Graphene’s Elegant Optics Explained
Graphene

Synopsis: Graphene’s Elegant Optics Explained

Theoretical calculations anchor graphene’s simple optical absorption in its two-dimensional structure instead of its cone-shaped energy bands. Read More »

More Articles