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 NASA's SDO sees partial eclipse in space
29.05.2017 | NASA/Goddard Space Flight Center

nachricht Strathclyde-led research develops world's highest gain high-power laser amplifier
29.05.2017 | University of Strathclyde

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: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>