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 Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences

nachricht The universe up close
15.01.2018 | Georg-August-Universität Göttingen

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: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

White graphene makes ceramics multifunctional

16.01.2018 | Materials Sciences

Breaking bad metals with neutrons

16.01.2018 | Materials Sciences

ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records

16.01.2018 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>