Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Playing quantum tricks with measurements

15.02.2013
A team of physicists at the University of Innsbruck, Austria, performed an experiment that seems to contradict the foundations of quantum theory – at first glance.

The team led by Rainer Blatt reversed a quantum measurement in a prototype quantum information processor. The experiment is enabled by a technique that has been developed for quantum error correction in a future quantum computer.


Ion trap
Photo: C. Lackner/IQOQI

Measurements on quantum systems have puzzled generations of physicists due to their counterintuitive properties. One of them is the fact that measurements on a quantum system are in general non-deterministic.

This means that even if the state of the system is completely known, it is impossible to determine the outcome of a single measurement. Furthermore, the measurement alters the system’s state so that a previous measurement will certainly return the same result as the first measurement. Thus the system is irreversibly altered by a measurement.

In their recent experiment, the scientists demonstrated that it is possible to reverse a measurement with the aid of a quantum error correction protocol. This seemingly contradicts the foundations of quantum theory which explicitly forbid the reversal of a quantum measurement. With a closer look it is easy to solve this riddle:

The team around Philipp Schindler transfers the information of a single particle onto an entangled state consisting of three particles. If now an individual particle is measured, its original state can be reconstructed from the information residing in the remaining two particles which is not forbidden by the laws of quantum mechanics.

Publication: Undoing a quantum measurement. Philipp Schindler, Thomas Monz, Daniel Nigg, Julio T. Barreiro, Esteban A. Martinez, Matthias F. Brandl, Michael Chwalla, Markus Hennrich, Rainer Blatt. Physical Review Letters 110, 070403 (2013). DOI: 10.1103/PhysRevLett.110.070403

Contact:
Philipp Schindler
Institute of Experimental Physics
University of Innsbruck, Austria
Telefon: +43 512 507-52453
E-Mail: philipp.schindler@uibk.ac.at
Christian Flatz
Public Relations Office
University of Innsbruck, Austria
Telefon: +43 512 507-32022
Mobil: +43 676 872532022
E-Mail: christian.flatz@uibk.ac.at

Dr. Christian Flatz | Universität Innsbruck
Further information:
http://www.uibk.ac.at
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.070403

More articles from Physics and Astronomy:

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

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: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>