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 A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University

nachricht A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg

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: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

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

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>