Asymmetric optical potential barrier becomes Maxwell’s demon

The hypothetical Maxwell’s demon opens and closes a tiny trapdoor dividing two containers of gas to shuttle atoms one way without exerting effort, raising the number of atoms in one container and lowering it in the other, apparently in violation of the second law of thermodynamics. Researchers at the University of Oregon (Eugene, OR) have created a Maxwell’s demon using an asymmetric optical potential barrier—although, as with any practical realization of such a demon, further investigation shows that the second law is always conserved.

Click here to enlarge image

Approximately 3 × 104 rubidium (87Rb) atoms at about 30 µK from a standard six-beam magneto-optic trap are loaded into a dipole trap, which has a 9.3 W beam from a 1090 nm fiber laser focused to a 31 µm waist. Two additional beams separated by 34 µm form the one-way barrier; the main beam is stabilized on a dip in the 85Rb saturated-absorption spectrum, which is at a frequency 1.16 GHz higher than that of the other (repumping) beam. After 100 ms, most of the atoms end up on one side of the trap; however, the spontaneous scattering of a barrier photon in each “trap-door” interaction carries away entropy, conserving the second law. Contact Daniel Steck at dsteck@uoregon.edu.

50 YEARS OF SOLID-STATE LASERS


A long way from the ruby laser

Most Popular Articles

Webcasts

Ray Optics Simulations with COMSOL Multiphysics

The Ray Optics Module can be used to simulate electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the ...

Multichannel Spectroscopy: Technology and Applications

This webcast, sponsored by Hamamatsu, highlights some of the photonic technology used in spectroscopy, and the resulting applications.

Handheld Spectrometers

Spectroscopy is a powerful and versatile tool that traditionally often required a large and bulky instrument. The combination of compact optics and modern pa...

Fracking, climate change, and lasers:  new tools to reduce fugitive methane emissions

This webcast, sponsored by Hamamatsu Corporation, covers recent developments and field deployments of compact quantum-cascade-laser (QCL)-based methane senso...
White Papers

Narrow-line fiber-coupled modules for DPAL pumping

A new series of fiber coupled diode laser modules optimized for DPAL pumping is presented, featur...

Accurate LED Source Modeling Using TracePro

Modern optical modeling programs allow product design engineers to create, analyze, and optimize ...

Optical Isolators Improve Engraving Performance of Pulsed Fiber Lasers

The deleterious effects of back reflections on pulsed fiber lasers used in marking and engraving ...
Technical Digests

ADHESIVES, SEALANTS, AND COATINGS: Solutions for optical technologies

A vast array of optical systems of various types and degrees of complexity require the use of adh...

WAVELENGTH-SWEPT LASERS: Dispersion-tuned fiber laser sweeps over a 140 nm range for OCT

By eliminating the use of mechanical tunable filters and instead tuning by intensity-modulation i...

Keeping pace with developments in photonic materials research

For demanding or custom spectroscopy solutions, care must be taken in selecting and integrating a...

HIGH-POWER FIBER LASERS: Working in the kilowatt regime

High-power materials-processing fiber lasers are available in an increasing variety of forms, as ...

Click here to have your products listed in the Laser Focus World Buyers Guide.
Social Activity
  •  
  •  
  •  
  •  
  •  
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS