Featured Research

from universities, journals, and other organizations

First Time Success: Individual Photons In A Trap

Date:
February 22, 2000
Source:
Max Planck Institute
Summary:
A research group of the Max Planck Institute of Quantum Optics and the Munich University, have for the first time realized Planck’s oscillators in an experiment. The founder of the quantum the­ory postulated that oscillators in matter are responsible for the emission of radiation in the form of photons. Scientists at the Max Planck Institute for Quantum Optics and the Munich University now succeeded to store individual photons in a resonator.

A research group of the Max Planck Institute of Quantum Optics and the Munich University, have for the first time realized Planck’s oscillators in an experiment (nature, 17 February 2000).

After 100 years, an idea of Max Planck’s (1858-1947) has been successfully demonstrated experimentally for the first time. The founder of the quantum the­ory postulated that oscillators in matter are responsible for the emission of radiation in the form of photons. Scientists at the Max Planck Institute for Quantum Optics and the Munich University now succeeded to store individual photons in a resonator. This resonator can be considered being equivalent to the oscillators assumed by Max Planck. The research group - Herbert Walther, Ben Varcoe and Simon Brattke - using the one-atom maser (Microwave Amplifica­tion by Simulated Emission of Radiation) developed at the Max Planck Insti­tute of Quantum Optics, experimentally produced radiation fields with a spe­cific number of photons. Since these fields can only be described by the laws of quantum physics, this radiation is also called non-classical radiation. It differs from the light of a laser, which obeys the laws of classical physics. New appli­cations in quantum communication and quantum cryptography, which are not possible with normal light or laser light, are now conceivable with this non-classical radiation. Noise reduced signals can be transmitted via individual photons, and messages can be sent without the risk of line tapping, as with quantum fields each line tap of a signal channel would immediately be recognised.

Light or - more generally - electromagnetic radiation, consists of individual energy quanta. Therefore the radiation is not emitted in a continuous flow, but rather is sent in discrete packages whereby the energy of a packet depends on the frequency of the radiation. In accordance with Planck’s opinion of 100 years ago, photons were emitted by the above mentioned oscillators.

The experiment to isolate individual photons is very complex. The radiation field, which consists of a fixed number of photons, must, with as minimal a loss as possible, be stored in the resonator of the one-atom maser (micromaser). This is achieved using a super-conducting niobium resonator. The principle, that is the basis for the micromaser, is the interaction of an individual atom with an individual oscillatory mode of the resonator.

The photons are generated in the resonator. A precise number of atoms are sent into the cavity and release their energy there in the form of photons. The emis­sion of the photons is caused by the so-called vacuum fluctuations representing the ground state of the quantum field. The control of the interaction time of the atom with the resonator guarantees that a photon is emitted with high probabil­ity. The precise number of photons generated and stored in the resonator depends thus on the number of atoms sent through the cavity. The average lifetime of a light quanta in a resonator amounts to 0.2 seconds, which is substantially longer than the inter­action time of an atom with the resonator. This storage time is orders of magni­tude larger than those achieved in previous experiments.

The number of photons present are measured by the scientists with the help of a rubidium atom, which is sent with defined velocity through the cavity. The atom is excited into an highly excited state called a Rydberg state, which allows the transitions in the microwave region. It enters the resonator in an excited state, emits and then reabsorbs a photon, thereby, leaving the resonator in an excited state. What is particular about the method, is that the photons are not destroyed by the measurement. The quantum states of the radiation field, achieved was of high purity. Fields of up to three photons could be generated.

One hundred years ago, Max Planck predicted the existence of photons or light quanta. Since their energy depends on the wavelength of the radiation, they have higher energy in the blue area of the visible spectrum than in the red sec­tion. Planck made these assumptions in order to explain the spectrum of a hot radiating body. At a temperature of about 800°C, a body begins to send out visible light. The light is initially red but changes its colour with increasing temperature, up to the point of incandescence. With increasing temperature further colours of the spectrum are added; these changes occur until eventually the entire spectrum is emitted. At the time, there was a lot of interest in an understanding of the spectrum of hot bodies, as one wanted to make the future use of the new electric light bulb as effective as possible.

Although the structure of the atom and therefore the mechanisms of light radia­tion were not particularly well known 100 years ago, Max Planck found an explanation for the spectrum of a hot body. In Planck’s vision, the radiation is produced through oscillators which emit the radiation. The oscil­lators - in accordance with the idea of oscillating electrons at the time - had an energy which corresponds to a precise number of photons. The energy distribu­tion of the oscillators was already given in the theory of thermodynamics.

With this assumption, Planck could explain the spectrum of a hot body. Through his revolutionary assumption, he had intuitively antici­pated what would become fact in future years, with the development of a full understanding of quantum mechanics. Today we know that Planck oscillators correspond to the quantum states of the electromagnetic field, which is exactly what the scientists of the Max Planck Institute for Quantum Optics and the Munich University have experimentally realized.


Story Source:

The above story is based on materials provided by Max Planck Institute. Note: Materials may be edited for content and length.


Cite This Page:

Max Planck Institute. "First Time Success: Individual Photons In A Trap." ScienceDaily. ScienceDaily, 22 February 2000. <www.sciencedaily.com/releases/2000/02/000222065520.htm>.
Max Planck Institute. (2000, February 22). First Time Success: Individual Photons In A Trap. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2000/02/000222065520.htm
Max Planck Institute. "First Time Success: Individual Photons In A Trap." ScienceDaily. www.sciencedaily.com/releases/2000/02/000222065520.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) — Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
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