Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Active optical clock

15.04.2009
Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, has proposed the concept, principles and techniques of active optical clock. The study is reported in Issue 54 (February, 2009) of Chinese Science Bulletin because of its significant research value.

Up to date, all realize that optical clocks are based on the laser absorption spectroscopy. Thus the available laser with narrowest linewidth limits the linewidth of state-of-the-art optical clocks. However, experimental and theoretical results show that the thermal Johnson noise of cavity mirrors degrades the quantum limitation of Schawlow-Townes linewidth formula of good-cavity laser.

In this work, Prof. Chen proposed the concept, principles and techniques of active optical clock. This is the first extension of Hydrogen maser, which is the most stable atomic microwave clock and related to the Nobel Prize in Physics 1989, from microwave regime to optical regime.

The lasing behavior of active optical clock is a second-order phase transition. On the one hand, the collective emission of radiation from all gain atoms strongly narrows the linewidth of active optical clock described by the modified Schawlow-Townes linewidth formula. On the other hand, in an active optical clock, any shift and noise of the center frequency due to cavity will be reduced to a cavity pulling effect, which can be several orders of magnitude smaller than the general cavity noise.

"Active optical clocks provide several new possibilities of applications: (i) more stable optical clock than any current atomic clocks; (ii) sub-natural linewidth laser spectroscopy; (iii) long coherence time laser with linewidth at mHz level; (iv) Ramsey laser combining stimulated emission process and Ramsey separated oscillatory fields method." commented Prof. Yiqiu Wang, the co-author of the first book "The principles of quantum frequency standards" in the research field of quantum frequency standards. A series of papers about active optical clock written by Prof. Chen and colleagues have been published in Chin. Sci. Bull., Phys. Rev. A, etc. "It is a novel idea. The active optical clock enriched and expanded the optical clock research." said one reviewer.

The author is affiliated at Institute of Quantum Electronics of Peking University. This institute has been conducting research in a variety of atomic clocks for four decades.

Supported by the National Natural Science Foundation of China (Grant Nos. 10874009) and the National Basic Research Program of China (Grant No. 2005CB724500).

Reference:

Chen J. Active optical clock. Chin Sci Bull. 2009; 54(3): 348-352 http://219.238.6.200/article?code=982008-2451&jccode=98

Wang Y Q. Optical clock based on stimulated emission radiation. Chin Sci Bull. 2009; 54(3): 347-347 http://219.238.6.200/article?code=982008-2580&jccode=98

Yu D and Chen J. Laser theory with finite atom-field interacting time. Phys. Rev. A 2008; 78, 013846-1-013846-8 http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PLRAAN000078000001013846000001&idtype=cvips&gifs=yes

J Chen | EurekAlert!
Further information:
http://www.pku.edu.cn

More articles from Physics and Astronomy:

nachricht NUS engineers develop novel method for resolving spin texture of topological surface states using transport measurements
26.04.2018 | National University of Singapore

nachricht European particle-accelerator community publishes the first industry compendium
26.04.2018 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

World's smallest optical implantable biodevice

26.04.2018 | Power and Electrical Engineering

Molecular evolution: How the building blocks of life may form in space

26.04.2018 | Life Sciences

First Li-Fi-product with technology from Fraunhofer HHI launched in Japan

26.04.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>