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.
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
Dr. Christian Flatz | Universität Innsbruck
UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire
NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences