Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A quantum connection between light and mechanics

02.02.2012
Optomechanical interactions
Researchers supported by the Swiss National Science Foundation (SNSF) have demonstrated a microscopic system in which light can be converted into a mechanical oscillation and back. This interaction is so strong that it becomes possible to control the motion of the oscillator at the level where quantum mechanics governs its behaviour.

Since the early 20th century, it is known that the movement of objects is ultimately governed by the laws of quantum mechanics, which predict some intriguing phenomena: An object could simultaneously be in two places at the same time, and it should always be moving a little, even at a temperature of absolute zero - the oscillator is then said to be in its quantum ground state. Yet we never experience such behaviour in the things we see around us and interact with in daily life.

Quantum strangeness

Indeed, quantum effects can only be observed on very well isolated systems, where the coupling to the surrounding environment is extremely weak. For large objects, the unavoidable coupling quickly washes out the quantum properties, in a process known as decoherence. Until recently, scientists were only able to observe quantum mechanical traits in the motion of tiny systems, such as single atoms or molecules. Now, a team of physicists in the EPFL’s Laboratory of Photonics and Quantum Measurement directed by Tobias Kippenberg has shown that it is possible to control the motion of an object, sufficiently large to be seen with the naked eye, at the level where quantum mechanics dominates. They achieve this by illuminating the object with laser light. The results are published in this week’s edition of Nature magazine*.

A ring of light

The structure is a carefully crafted glass donut on a microchip, with a diameter of 30 micrometres (about one half of a hair’s diameter) which can vibrate at a well-defined frequency. At the same time, it acts as a racetrack for light, which can circle around the circumference of the donut. In turning the bend, the light exerts a little force on the glass surface, an effect called 'radiation pressure'. Although this force is very small, in these structures it can become appreciable since light circles around the structure up to a million times before being lost. The radiation pressure force can make the ring move, causing it to vibrate like a finger running along the rim of a wineglass. But it can in fact also dampen the vibrations, and thus cool down the oscillatory motion.

Cold, colder, ...

Cooling is crucial to reaching the regime of quantum mechanical motion, as this is normally overshadowed by random thermal fluctuations. For this reason, the structure is brought to a temperature of less than one degree above absolute zero. Radiation pressure damping by laser light launched into the donut then cools the motion down by an extra factor 100. The oscillator is cooled so much that it spends a large fraction of the time in its quantum ground state. But even more importantly: The interaction between light and the movement of the oscillator can be made so strong that the two form an intimate connection. A small excitation in the form of a light pulse can fully transform into a small vibration and back again. For the first time, this transformation between light and motion is made to occur within a time that is short enough such that the quantum properties of the original light pulse are not lost in the process through decoherence. By outpacing decoherence, the current results provide a powerful way to control the quantum properties of the oscillator motion, and see the peculiar predictions of quantum mechanics at play in human-made objects.

* E. Verhagen, S. Deléglise, S. Weis, A. Schliesser and T. J. Kippenberg (2012). Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode. Nature online DOI: 10.1038/nature10787
(available as a pdf-file from the SNSF; e-mail: com@snf.ch)

Contact:
Professor Tobias Kippenberg
Laboratory of Photonics and Quantum Measurements
EPFL
CH-1015 Lausanne
E-mail: tobias.kippenberg@epfl.ch
Tel: +41 (0)21 693 44 28

Kommunikation SNF | idw
Further information:
http://www.epfl.ch
http://www.snf.ch

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>