photons tagged posts

For the first time, physicists have successfully converted electrical signals into photons and radiated them in specific directions using a low-footprint optical antenna that is only 800 nanometers in size.

Directional antennas convert electrical signals to radio waves and emit them in a particular direction, allowing increased performance and reduced interference. This principle, which is useful in radio wave technology, could also be interesting for miniaturised light sources...

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...

This is an infographic explaining the fact that 10 trillionths of a suntan comes from beyond our galaxy. Credit: ICRAR/Dan Hutton

Lie on the beach this summer and your body will be bombarded by about sextillion photons of light per second.Most of these photons, originate from the Sun but a very small fraction have travelled across the Universe for billions of years before ending their existence when they collide with your skin. Astronomers have now accurately measured the light hitting Earth from outside our galaxy over a very broad wavelength range. The research looked at photons whose wavelengths vary from a fraction of a micron (damaging) to millimetres (harmless).

But radiation from outside the galaxy constitutes only ten trillionths of your suntan, so there is no immediate need for al...

Image of one of the graphene-based devices Xu and colleagues worked with. Credit: Lei Wang

In traditional light-harvesting methods, energy from 1 photon only excites 1 electron or none depending on the absorber’s energy gap. The remaining energy is lost as heat. But a new article describe an approach to coax photons into stimulating multiple electrons. Their method exploits some surprising quantum-level interactions to give one photon multiple potential electron partners.

Wu and Xu in UW’s Dept of Materials Science & Engineering and the Det of Physics, made this surprising discovery using graphene.
The researchers took a single atom layer of graphene and sandwiched it between 2 thin layers of boron-nitride. Electrons do not flow easily within boron-nitride so it is an insulator.

When the g...