Researchers discern the shapes of high-order Brownian motions

November 17, 2014, Case Western Reserve University
This image spatially maps and visualizes the shapes of multimode Brownian motions. The to of the image is a false-colored scanning electron micrographs of a silicon carbide (SiC) microdisk supported by a central pedestal made of 500nm-thick silicon oxide. The bottom image is a scanned map of vibrations of the microdisk due to a high-order mode Brownian motion. Credit: Philip Feng

For the first time, scientists have vividly mapped the shapes and textures of high-order modes of Brownian motions—in this case, the collective macroscopic movement of molecules in microdisk resonators—researchers at Case Western Reserve University report.

To do this, they used a record-setting scanning optical interferometry technique, described in a study published today in the journal Nature Communications.

The new technology holds promise for multimodal sensing and signal processing, and to develop optical coding for computing and other information-processing functions by exploiting the spatially resolved multimode Brownian resonances and their splitting pairs of modes.

"What we found agrees with the expected Brownian motions in high-order modes," said Philip Feng, assistant professor of electrical engineering and computer science at Case Western Reserve and senior author of the study. "But it has been pretty amazing and exhilarating to directly visualize these modes down to the fundamental limit of intrinsic Brownian motions."

In his lab at Case School of Engineering, Feng worked closely with research associate Max Zenghui Wang and PhD student Jaesung Lee on the study.

Interferometry uses the interference of light waves reflected off a surface to measure distances, a technique invented by Case School of Applied Science physicist Albert A. Michelson (who won the Nobel prize in science in 1907). Michelson and Western Reserve University chemist Edward Morley used the instrument to famously disprove that light traveled through "luminous ether" in 1887, setting the groundwork for Albert Einstein's theory of relativity.

The technology has evolved since then. The keys to Feng's new interferometry technique are focusing a tighter-than-standard laser spot on the surface of novel silicon carbide microdisks.

The microdisks, which sit atop pedestals of silicon oxide like cymbals on stands, are extremely sensitive to the smallest fluctuations arising from Brownian motions, even at thermodynamic equilibrium. Hence, they exhibit very small oscillations without external driving forces. These oscillations include fundamental and higher modes, called thermomechanical resonances.

Some of the light from the laser reflects back to a sensor after striking the top surface of the silicon dioxide film. And some of the light is refracted through the film and reflected back on a different path, causing interference in the light waves.

The narrow laser spot scans the disk surface and measures movement, or displacement, of the disk with a sensitivity of about 7 femtometers per square-root of a hertz at room temperature, which researchers believe is a record for interferometric systems. To put that in perspective, the width of a hair is about 40 microns, and a femtometer is 100 million times smaller than a micron.

Although higher frequency modes have small motion amplitudes, the technology enabled the group to spatially map and clearly visualize the first through ninth Brownian modes in the high frequency band, ranging from 5.78 to 26.41 megahertz.

In addition to detecting the shapes and textures of Brownian motions, multimode mapping identified subtle structural imperfections and defects, which are ubiquitous but otherwise invisible, or can't be quantified most of the time. This capability may be useful for probing the dynamics and propagation of defects and defect arrays in nanodevices, as well as for future engineering of controllable defects to manipulate information in silicon carbide nanostructures

The high sensitivity and spatial resolution also enabled them to identify mode splitting, crossing and degeneracy, spatial asymmetry and other effects that may be used to encode information with increasing complexity. The researchers are continuing to explore the capabilities of the technology.

Explore further: Lord of the microrings: Team reports breakthrough in microring laser cavities

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mikep608
1 / 5 (1) Nov 18, 2014
"Michelson and Western Reserve University chemist Edward Morley used the instrument to famously disprove that light traveled through "luminous ether" in 1887, setting the groundwork for Albert Einstein's theory of relativity."
I like how in 1887 i repeat 1887 they 'proved' that light does not move through Aether. What if the world gave it a rethink, did the correct experiments, and discovered that light IS Aether, and not moving through it?
HERE'S MY WEBPAGE LINK. I LIKE TO REINTERPRET EXPERIMENTAL RESULTS SO WE CAN HAVE MORE USEFUL KNOWLEDGE TO GUIDE US IN PROGRESS

https://www.faceb...timeline

mikep608
1 / 5 (1) Nov 18, 2014
"Some of the light from the laser reflects back to a sensor after striking the top surface of the silicon dioxide film. And some of the light is refracted through the film and reflected back on a different path, causing interference in the light waves."
I have written some very interesting things about light interference on my webpage. It is the section about the slit experiment
HERE'S MY WEBPAGE LINK. I LIKE TO REINTERPRET EXPERIMENTAL RESULTS SO WE CAN HAVE MORE USEFUL KNOWLEDGE TO GUIDE US IN PROGRESS

https://www.faceb...timeline
liquidspacetime
not rated yet Nov 20, 2014
Aether has mass. Aether physically occupies three dimensional space. Aether is physically displaced by the particles of matter which exist in it and move through it.

The Milky Way's halo is not a clump of stuff anchored to the Milky Way. The Milky Way is moving through and displacing the aether.

The Milky Way's halo is the state of displacement of the aether.

The Milky Way's halo is the deformation of spacetime.

What is referred to geometrically as the deformation of spacetime physically exists in nature as the state of displacement of the aether.

A moving particle has an associated aether displacement wave. In a double slit experiment the particle travels through a single slit and the associated wave in the aether passes through both.

Q. Why is the particle always detected traveling through a single slit in a double slit experiment?
A. The particle always travels through a single slit. It is the associated wave in the aether which passes through both.

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