Category Physics

Artistic depiction of the generation of three correlated photons from quantum vacuum. Credit: Antti Paraoanu

Microwaves created at near 0K provide uniquely correlated and controllable states. Researchers at Aalto University have demonstrated the suitability of microwave signals in coding of information for quantum computing. Previous development of the field has been focusing on optical systems. They used a microwave resonator based on extremely sensitive measurement devices, ie superconductive quantum interference devices (SQUIDs). The resonator was cooled down and kept near absolute zero, where thermal motion freezes. This state corresponds to perfect darkness where no photon, a particle of electromagnetic radiation eg visible light or microwaves, is present.

However, in this state (quan...

It is now possible for machines to learn how natural or artificial systems work by observing them, without being told what to look for

It is now possible for machines to learn how natural or artificial systems work by simply observing them, without being told what to look for, according to researchers at the University of Sheffield. This could mean advances in the world of technology with machines able to predict, among other things, human behaviour. The discovery takes inspiration from the work of pioneering computer scientist Alan Turing, who proposed a test, which a machine could pass if it behaved indistinguishably from a human. In this test, an interrogator exchanges messages with two players in a different room: one human, the other a machine.

The interrogator has to find out which o...

An illustration shows what happens in a typical experiment with SLAC’s LCLS X-ray laser, top, versus what happened in this study with an especially intense X-ray pulse. Normally the X-ray pulses — which are shown coming in from the right — scatter off electrons in a sample and produce a pattern in a detector. But when researchers cranked up the intensity of the X-ray pulses, the pulses seemed to go straight through the sample, as if it were not there, and the pattern in the detector vanished. Two recent papers describe and explain this surprising result, which is due to a ‘nonlinear’ effect where particles of X-ray light team up to cause unexpected things to happen. Credit: SLAC National Accelerator Laboratory

A nonlinear’ effect seemingly turns materials transparent is seen for the ...

Between two mirrors, the quantum dot filters the light beams with just one photon per package out of the laser, so that only packages with multiple photons remain. Credit: Leiden Institute of Physics

Leiden physicists have manipulated light with large artificial atoms, ie quantum dots. Before, this has only been accomplished with actual atoms. It is an important step toward light-based quantum technology. When you point a laser pointer at the screen during a presentation, an immense number of light particles races through the air at a billion km/hour. They don’t travel in a continuous flow, but in packages containing varying numbers of particles. Sometimes as many as 4 so-called photons pass by, and other times none at all...