Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Shape matters when light meets atom
by Staff Writers
Singapore (SPX) Dec 06, 2016


Scientists at the Centre for Quantum Technologies at the National University of Singapore have shown that a photon's shape affects how it is absorbed by a single atom. This artist's illustration is not to scale: in the experiment the photons are some 4 meters long, while the atom is less than a nanometer wide. Image courtesy Timothy Yeo / Centre for Quantum Technologies, National University of Singapore. For a larger version of this image please go here.

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what you're looking at. Some photons reflect off, reaching your eyes. Others get absorbed. The main decider of which happens is the photon's energy - its colour. But look closely at the moment that light meets matter, and there's more to be discovered. Scientists at the Centre for Quantum Technologies (CQT) at the National University of Singapore have just shown that a photon's shape also affects how it is absorbed by a single atom.

We don't often think of photons as being spread out in time and space and thus having a shape, but the ones in this experiment were some four metres long. Christian Kurtsiefer, Principal Investigator at CQT, and his team have learned to shape these photons with extreme precision. For the research, published in Nature Communications, the team worked with Rubidium atoms and infrared photons. They shone the photons one at a time onto a single atom.

"Our experiments look at the most fundamental interaction between matter and light" says Victor Leong, for whom the work contributed to a PhD degree. A four-metre photon takes about 13 nanoseconds to pass the atom. Every time a photon was sent towards the atom, the team watched to see if and when the atom got excited. By noting the excitation times and collecting them together, the researchers could map the probability of the atom absorbing the photon as a function of time.

The team tested two different photon shapes - one rising in brightness, the other decaying. Hundreds of millions of measurements made over 1500 hours showed that the overall probability that a single Rubidium atom would absorb a single photon of either type was just over 4%. However, when the team looked at the process on nanoscale timeframes, they saw that the probability of absorption at each moment depends on the photon's shape.

The researchers found that if the photon arrived dimly, from the atom's point of view, then ended brightly, the peak probability of excitation was just over 50% higher than when the photon arrived bright and had a long, fading tail.

Researchers had expected atoms might prefer to soak up the rising photons. That's because of what happens naturally when an excited atom decays. Then, the atom spits out a decaying photon. Imagine running the process backwards - the equations say it should look the same - and the atom would arrive with rising brightness. "Our choice of photon shape was inspired by the time symmetry of quantum mechanics," says coauthor Matthias Steiner.

The work also builds understanding for technologies that rely on light-matter interactions. Some proposals for quantum technologies such as communication networks, sensors and computers require that a photon writes information into an atom by being absorbed. The photon knocks the atom into an excited state. To build reliable devices, scientists will need to control the interaction. "You can only engineer what you can understand," says coauthor Alessandro Cere

Research paper: "Time-resolved scattering of a single photon by a single atom"


Comment on this article using your Disqus, Facebook, Google or Twitter login.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Centre for Quantum Technologies at the National University of Singapore
Space Technology News - Applications and Research






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
A watershed moment in understanding how H2O conducts electricity
New Haven CT (SPX) Dec 02, 2016
Scientists have taken spectroscopic snapshots of nature's most mysterious relay race: the passage of extra protons from one water molecule to another during conductivity. The finding represents a major benchmark in our knowledge of how water conducts a positive electrical charge, which is a fundamental mechanism found in biology and chemistry. The researchers, led by Yale chemistry profess ... read more


TECH SPACE
Orbital ATK Ends 2016 with Three Successful Cargo Resupply Missions to ISS

Space Food Bars Will Keep Orion Weight Off and Crew Weight On

Russian Space Sector Overcomes Failures

Embry-Riddle Students Join Project PoSSUM to Test Prototype Spacesuits in Zero-G

TECH SPACE
Russia to Launch Fewer Spacecraft in 2016 Than US, China for First Time

Soyuz-U Carrier Rocket Installed to Baikonur Launching Pad

Ariane 5's impressive 75 in-a-row launch record

Vega ready for GOKTURK-1A to be encapsulated

TECH SPACE
CaSSIS Sends First Images from Mars Orbit

First views of Mars show potential for ESA's new orbiter

ExoMars space programme needs an extra 400 million euros

Opportunity team onsidering a new route due to boulder field

TECH SPACE
China launches 4th data relay satellite

Material and plant samples retrieved from space experiments

Chinese astronauts return to earth after longest mission

China completes longest manned space mission yet

TECH SPACE
ESA looks at how to catch a space entrepreneur

Thales and SENER to jointly supply optical payloads for space missions

Citizens' space debate: the main findings and the future

Two-year extensions confirmed for ESA's science missions

TECH SPACE
New technology of ultrahigh density optical storage researched at Kazan University

Earth's 'technosphere' now weighs 30 trillion tons

A watershed moment in understanding how H2O conducts electricity

Researchers take first look into the 'eye' of Majoranas

TECH SPACE
Biologists watch speciation in a laboratory flask

Timing the shadow of a potentially habitable extrasolar planet

Fijian ants began farming 3 million years ago

Researchers propose low-mass supernova triggered formation of solar system

TECH SPACE
New analysis adds to support for a subsurface ocean on Pluto

Pluto follows its cold, cold heart

New Analysis Supports Subsurface Ocean on Pluto

Mystery solved behind birth of Saturn's rings




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement