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


Features

More Features »

Subject Areas

OpticsNonlinear Dynamics

Previous Synopsis

Mesoscopics

Artificial graphene

Read More »

Next Synopsis

Atomic and Molecular Physics

Making monopoles

Read More »

Related Articles

Synopsis: Blocking out Starlight
Astrophysics

Synopsis: Blocking out Starlight

A proposed telescope update could enable incoming light from multiple stars to be simultaneously blocked, making it easier to image exoplanets orbiting two or more stars. Read More »

Focus: 3D Images 10 Times Faster
Interdisciplinary Physics

Focus: 3D Images 10 Times Faster

3D x-ray phase-contrast images take as little as one-tenth the usual time to acquire using a technique that halves the number of required “photos.” Read More »

Viewpoint: Photonic Hat Trick
Optics

Viewpoint: Photonic Hat Trick

Two independent groups have provided the first experimental demonstration of genuine three-photon interference. Read More »

More Articles