quantum physics tagged posts

Semiconductor electronics is getting faster and faster — but at some point, physics no longer permits any increase. The speed can definitely not be increased beyond one petahertz (one million gigahertz), even if the material is excited in an optimal way with laser pulses.

How fast can electronics be? When computer chips work with ever shorter signals and time intervals, at some point they come up against physical limits. The quantum-mechanical processes that enable the generation of electric current in a semiconductor material take a certain amount of time. This puts a limit to the speed of signal generation and signal transmission.

TU Wien (Vienna), TU Gra...

Researchers at the University of Bonn have created a gas of light particles that can be extremely compressed. Their results confirm the predictions of central theories of quantum physics. The findings could also point the way to new types of sensors that can measure minute forces. The study is published in the journal Science.

If you plug the outlet of an air pump with your finger, you can still push its piston down. The reason: Gases are fairly easy to compress — unlike liquids, for example. If the pump contained water instead of air, it would be essentially impossible to move the piston, even with the greatest effort.

Gases usually consist of at...

What came first, the chicken or the egg? Or both?
Credit: © olhastock / Fotolia

The “chicken or egg” paradox was first proposed by philosophers in Ancient Greece to describe the problem of determining cause-and-effect. Now, a team of physicists from The University of Queensland and the NÉEL Institute has shown that, as far as quantum physics is concerned, the chicken and the egg can both come first.

Dr Jacqui Romero from the ARC Centre of Excellence for Engineered Quantum Systems said that in quantum physics, cause-and-effect is not always as straightforward as one event causing another. “The weirdness of quantum mechanics means that events can happen without a set order,” she said. “Take the example of your daily trip to work, where you travel partly by bus and partly by train...

Cosimo Rusconi (l.) and Oriol Romero-Isart (r.) play with a levitron to illustrate their work on nano magnets.
Credit: IQOQI Innsbruck/M.R.Knabl

Quantum physicists have now shown that, despite Earnshaw’s theorem, nanomagnets can be stably levitated in an external static magnetic field owing to quantum mechanical principles. The quantum angular momentum of electrons, which also causes magnetism, is accountable for this mechanism.

Already in 1842, British mathematician Samuel Earnshaw proved that there is no stable configuration of levitating permanent magnets. If one magnet is levitated above another, the smallest disturbance will cause the system to crash...