Featured Research

from universities, journals, and other organizations

From a classical laser to a 'quantum laser'

Date:
March 31, 2010
Source:
University of Innsbruck
Summary:
Researchers in Austria have successfully realized a single-atom laser, which shows the properties of a classical laser as well as quantum mechanical properties of the atom-photon interaction.

A high-finesse optical cavity consists of two mirrors, which traps and accumulates the photons emitted by the ion into a mode. The ion is excited cyclically by an external laser and at each cycle a photon is added to the cavity mode, which amplifies the light.
Credit: Piet Schmidt

Rainer Blatt's and Piet Schmidt's research team from the University of Innsbruck has successfully realized a single-atom laser, which shows the properties of a classical laser as well as quantum mechanical properties of the atom-photon interaction.

The scientists have published their findings in the journal Nature Physics.

The first laser was developed 50 years ago. Today we cannot imagine life without the artificially produced light waves -- lasers have become an integral part of many appliances used in telecommunication, household, medicine, and research.

A laser normally consists of a gain medium, which is electrically or optically pumped, inside a highly reflective optical cavity (or resonator). The light in the cavity bounces back and forth in the form of modes whereby it is amplified repeatedly. One of the distinctive features of a classical laser is the steep increase of output power when a certain pumping threshold is reached. At this point the gain (amplification by the medium) equals the losses as the light circulates through the cavity. This is caused by the amplification of the interaction between light and atoms: The more photons are present in a mode the stronger the amplification of the light in the mode. This stimulated emission is usually observed in macroscopic lasers comprising of many atoms and photons.

The Innsbruck researchers have demonstrated that a laser threshold can be achieved at the smallest possible building block of a laser: a single atom, which interacts with a single mode in an optical cavity. A single calcium ion is confined in an ion trap and excited by external lasers. A high-finesse optical cavity consists of two mirrors, which traps and accumulates the photons emitted by the ion into a mode. The ion is excited cyclically by an external laser and at each cycle a photon is added to the cavity mode, which amplifies the light.

For strong atom-cavity coupling the regime of atom and cavity shows quantum mechanical behavior: Only single photons can be introduced into the cavity. "As a consequence, stimulated emission and threshold are absent," explains Franηois Dubin, a French postdoc and first author of the publication. A 'quantum laser' was demonstrated in a similar regime some years ago. What is new in the experiment of the Innsbruck researchers is the ability to tune the coupling of the atom to the cavity mode. By choosing the right parameter of the drive laser, the physicists were able to achieve stronger excitation and, consequently, add more photons to the cavity. Although there was still less than one photon in the cavity, the researchers observed stimulated emission in the form of a threshold.

"A single atom is a very weak amplifier. As a consequence, the threshold is much less pronounced than in classical lasers," explains Piet Schmidt.

An even stronger excitation does not result in a higher output, which is the case in a conventional laser, but in the quenching of the output due to quantum mechanical interference. This constitutes an intrinsic limitation of miniature single-atom lasers. Therefore, researchers from the University of Innsbruck want to further investigate the transition between quantum and classical lasers through the controlled addition of more and more ions interacting with the light field.

This research work is supported by the Austrian Science Fund, the European Commission and the Federation of Austrian Industry Tirol.


Story Source:

The above story is based on materials provided by University of Innsbruck. Note: Materials may be edited for content and length.


Journal Reference:

  1. Franηois Dubin, Carlos Russo, Helena G. Barros, Andreas Stute, Christoph Becher, Piet O. Schmidt, Rainer Blatt. Quantum to classical transition in a single-ion laser. Nature Physics, 2010; DOI: 10.1038/nphys1627

Cite This Page:

University of Innsbruck. "From a classical laser to a 'quantum laser'." ScienceDaily. ScienceDaily, 31 March 2010. <www.sciencedaily.com/releases/2010/03/100331081129.htm>.
University of Innsbruck. (2010, March 31). From a classical laser to a 'quantum laser'. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2010/03/100331081129.htm
University of Innsbruck. "From a classical laser to a 'quantum laser'." ScienceDaily. www.sciencedaily.com/releases/2010/03/100331081129.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) — Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) — When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins