Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Shaken, not stirred: Control Over Complex Systems Consisting of Many Quantum Particles

05.06.2014

At TU Vienna, a new method was developed to utilize quantum mechanical vibrations for high precision measurements. The well-known concept of the Ramsey interferometer is applied to a complex multi particle system consisting of hundreds of atoms.

Sometimes quantum particles behave like waves. This phenomenon is often used for high precision measurements, for instance in atomic clocks. Usually, only the wave properties of single particles play a role, but now researchers at the Vienna Center for Quantum Science and Technology, Vienna University of Technology have succeeded in quantum mechanically controlling hundreds of Rubidium atoms of an ultracold Bose-Einstein-condensate by shaking it in just the right way. Now, not only internal states of atoms can be used for interferometric measurements, but also the collective motional state of all particles.


Shaken: The time evolution of the vibration of the condensate

Superpositions of Different States
According to quantum theory, some physical quantities can only have certain discrete values. If, for instance, the energy of an electron inside an atom is measured, it is always found in special energy states – other energy values are just not allowed. It is similar with the motion of particles, if they are confined to small spaces.

“We catch hundreds of Rubidium atoms in a magnetic trap and cool them so that they form an ultracold Bose-Einstein condensate”, says Professor Jörg Schmiedmayer from the Institute for Atomic and Subatomic Physics at the Vienna University of Technology. “This Bose-Einstein-condensate moves as a gigantic matter wave.” The laws of quantum physics, however, do not permit every kind of motion, but only a certain set of possible motion waves.

Different Wave States
“It is a bit like blowing a flute”, says Sandrine van Frank. “When you blow it, a sound wave is created. If you blow it harder, you can produce a high-pitched overtone.” In quantum physics, however, different states can be excited at the same time. With a precisely tailored electromagnetic pulse, developed in collaboration with Prof. Tommaso Calarco of the Institute for Quantum Information at the Univ. Ulm, the Bose-Einstein condensate can be shaken, so that it does not only occupy one of the possible motion states, but two at the same time.

Such a superposition of states is something quite normal in quantum physics. The amazing thing is that a system with hundreds of atoms and many degrees of freedom – in quantum terms something incredibly huge – can be prepared in such a superposition state. Usually, quantum superpositions are extremely fragile. The larger the object, the easier it is to destroy the quantum properties of a superposition of allowed quantum states – a phenomenon called “decoherence”. Today, decoherence is considered to be the hardest problem for the development of new quantum technologies such as the Quantum Computer.

“After we have shaken the condensate with the pulse, it performs(exhibits) two different vibrational motions at the same time”, says van Frank. “After a while, we shake the condensate a second time, recombining the two superimposed motions.” Which of the two possible kinds of motion prevails in the end depends on the time delay between the two pulses and on the quantum phase of the superposition. Such a sequence of pulses is known as “Ramsey sequence” and is used for high-precision measurements in many areas. Now this technique was successfully transferred to the many-particle states of a Bose-Einstein condensate.

Just the Right Kick
In order to control the system, it was crucial to find exactly the right kind of pulse with which the condensate has to be shaken. It is supposed to enable a transition between the two vibration states that should be superimposed, but it should not be able to create any other possible states. Excluding all the other states turned out to be crucial for suppressing the unwanted decoherence effect.

“Our result proves that vibrational states of hundreds of atoms can be used for quantum experiments”, says Schmiedmayer. These states can be used to store information, and one day maybe even to do calculations. The remarkable stability of these states also gives insight into decoherence phenomena of large systems, consisting of many particles – an extremely fruitful field of research. In a next step, not only vibrations but also rotation states of the Bose-Einstein condensate will be studied. In the quantum world, both  are possible at the same time: shaken AND stirred.

The work has now been published in the journal “Nature Communications”. The team at the Vienna University of Technology was supported by researchers from Hamburg University and Ulm University.
Nature Communications 5,  4009
doi:10.1038/ncomms5009


Additional Information:
Prof. Jörg Schmiedmayer
Institute of Atomic and Subatomic Phyisics,
Vienna Center for Quantum Science and Technology (VCQ)
Vienna University of Technology
Stadionallee 2, 1020 Wien
+43 (1) 58801 141888
schmiedmayer@AtomChip.org

Prof. Thorsten Schumm
Institute of Atomic and Subatomic Phyisics,
Vienna Center for Quantum Science and Technology (VCQ)
Vienna University of Technology
Stadionallee 2, 1020 Wien
T: +43-1-58801-141896
thorsten.schumm@tuwien.ac.at

Sandrine van Frank, MSc
Institute of Atomic and Subatomic Phyisics,
Vienna Center for Quantum Science and Technology (VCQ)
Vienna University of Technology
Stadionallee 2, 1020 Wien
T: +43-1-58801-141889
sandrine.frank@tuwien.ac.at

florian.aigner@tuwien.ac.at

Florian Aigner | Eurek Alert!
Further information:
http://www.tuwien.ac.at/en/news/news_detail/article/8820/

Further reports about: Atomic Bose-Einstein Quantum Rubidium Subatomic Technology energy

More articles from Physics and Astronomy:

nachricht Optical lenses, hardly larger than a human hair
29.06.2016 | Universität Stuttgart

nachricht Clandestine black hole may represent new population
28.06.2016 | International Centre for Radio Astronomy Research

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: Optical lenses, hardly larger than a human hair

3D printing enables the smalles complex micro-objectives

3D printing revolutionized the manufacturing of complex shapes in the last few years. Using additive depositing of materials, where individual dots or lines...

Im Focus: Flexible OLED applications arrive

R2D2, a joint project to analyze and development high-TRL processes and technologies for manufacture of flexible organic light-emitting diodes (OLEDs) funded by the German Federal Ministry of Education and Research (BMBF) has been successfully completed.

In contrast to point light sources like LEDs made of inorganic semiconductor crystals, organic light-emitting diodes (OLEDs) are light-emitting surfaces. Their...

Im Focus: Unexpected flexibility found in odorant molecules

High resolution rotational spectroscopy reveals an unprecedented number of conformations of an odorant molecule – a new world record!

In a recent publication in the journal Physical Chemistry Chemical Physics, researchers from the Max Planck Institute for the Structure and Dynamics of Matter...

Im Focus: 3-D printing produces cartilage from strands of bioink

Strands of cow cartilage substitute for ink in a 3D bioprinting process that may one day create cartilage patches for worn out joints, according to a team of engineers. "Our goal is to create tissue that can be used to replace large amounts of worn out tissue or design patches," said Ibrahim T. Ozbolat, associate professor of engineering science and mechanics. "Those who have osteoarthritis in their joints suffer a lot. We need a new alternative treatment for this."

Cartilage is a good tissue to target for scale-up bioprinting because it is made up of only one cell type and has no blood vessels within the tissue. It is...

Im Focus: First experimental quantum simulation of particle physics phenomena

Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.

Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Conference ‘GEO BON’ Wants to Close Knowledge Gaps in Global Biodiversity

28.06.2016 | Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

 
Latest News

Building a better battery

29.06.2016 | Life Sciences

New way out: Researchers show how stem cells exit bloodstream

29.06.2016 | Life Sciences

Crucial peatlands carbon-sink vulnerable to rising sea levels

29.06.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>