Defying physics, engineers prove a magnetic field for light

Defying physics, engineers prove a magnetic field for light: When a light wave travels under normal conditions, its phase is proportional to how far it traveled, but it is unaffected by what path it has taken. Just like a magnetic field causes a current to switch direction, the researchers showed that by modulating the light with their device, they could make the phase of the light change not only as a function of distance traveled, but also by the shape of its path.
An array of such modulators would be powerful enough to create a field for light that is equivalent to the magnetic field for electrons; phases of light could be controlled arbitrarily by each of the modulators. This means that the phase of transmitted light could depend on the path it has taken from point A to point B, Lipson explained.

'Solid light' could compute previously unsolvable problems - ScienceBlog.com

'Solid light' could compute previously unsolvable problems - ScienceBlog.com: To build their machine, the researchers created a structure made of superconducting materials that contains 100 billion atoms engineered to act as a single “artificial atom.” They placed the artificial atom close to a superconducting wire containing photons.
By the rules of quantum mechanics, the photons on the wire inherit some of the properties of the artificial atom – in a sense linking them. Normally photons do not interact with each other, but in this system the researchers are able to create new behavior in which the photons begin to interact in some ways like particles.
“We have used this blending together of the photons and the atom to artificially devise strong interactions among the photons,” said Darius Sadri, a postdoctoral researcher and one of the authors. “These interactions then lead to completely new collective behavior for light – akin to the phases of matter, like liquids and crystals, studied in condensed matter physics.”

Terahertz Chip Identifies Short Strands of DNA | MIT Technology Review

Terahertz Chip Identifies Short Strands of DNA | MIT Technology Review: They say that the sequence of bases in an oligonucleotide determines the way in which the strand resonates at frequencies in the terahertz range...

...they have tested it using a device they call a silicon nanosandwich, a quantum well of p-type silicon surrounded by barriers doped with boron. This produces terahertz radiation inside the well where the oligonucleotide is deposited at a concentration that allows a single molecule to enter.

New Material, Darker Than Black, Could Help Space Cameras See Better | Popular Science

New Material, Darker Than Black, Could Help Space Cameras See Better | Popular Science: Scientists make Vantablack by depositing carbon nanotubes close together on a thin sheet of aluminum. The tiny spaces between the tubes trap light, preventing it from reflecting off the material. A number of research groups have made super-absorbing black materials with similar microstructures. One advantage of Vantablack is that it doesn't require as high of temperatures to make as other carbon nanotube materials, according to Surrey NanoSystems. That means engineers can deposit Vantablack coatings on a wider range of materials.

Harnessing the speed of light | MIT News Office

Harnessing the speed of light | MIT News Office: One of Fang’s key discoveries is finding how to beat the diffraction of light. Since light and sound waves tend to spread out when blocked by an obstacle, images and communication signals can become blurry and muddled. In his lab, Fang discovered that by breaking the diffraction barrier, light signals can be sent at 10 times greater capacity. This has allowed him to produce results on the sub-nanometer scale, with light as a machining tool providing “a new degree of precision,” he says.

Hollow optical fibers for UV light

Hollow optical fibers for UV light: Researchers... have tested a new type of optical fibre with a hollow core and have found out that this type of optical fibre was able to guide UV laser light without being damaged and with acceptable loss.

New metamaterial gives light a one-way ticket

New metamaterial gives light a one-way ticket:  ...The silver-glass structure is an example of a "hyperbolic" metamaterial, which treats light differently depending on which direction the waves are traveling...

While the second set of grates let light escape the material, their spacing was slightly different from that of the first grates. As a result, the reverse-direction grates bent incoming light either too much or not enough to propagate inside the silver-glass layers. Testing their structures, the researchers found that around 30 times more light passed through in the forward direction than in reverse, a contrast larger than any other achieved thus far with visible light.

Combining materials that could be made using existing methods was the key to achieving one-way transmission of visible light, Lezec says. Without the intervening silver-and-glass blocks, the grates would have needed to be fabricated and aligned more precisely than is possible with current techniques. "This three-step process actually relaxes the fabrication constraints," Lezec says.

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium: Because all previous speed-of-light calculations have relied only on general relativity, they do not take into account the tiny effects of quantum mechanics. But these effects are significant over such long distances and through such a large mass as the Milky Way, says Franson...

Franson’s idea is that the gravitational potential must influence the electron-positron pair because they have mass. “Roughly speaking, the gravitational potential changes the energy of a virtual electron-positron pair, which in turn produces a small change in the energy of a photon,” he says. “This results in a small correction to the angular frequency of a photon and thus its velocity.”

Quantum biology: Algae evolved to switch quantum coherence on and off

Quantum biology: Algae evolved to switch quantum coherence on and off: "Most cryptophytes have a light-harvesting system where quantum coherence is present. But we have found a class of cryptophytes where it is switched off because of a genetic mutation that alters the shape of a light-harvesting protein.
"This is a very exciting find. It means we will be able to uncover the role of quantum coherence in photosynthesis by comparing organisms with the two different types of proteins."

Light Could Restore Lost Hearing - Scientific American

Light Could Restore Lost Hearing - Scientific American: In a study that appeared in March in the Journal of Clinical Investigation, the researchers used viruses to implant genes for light sensitivity into mouse embryos of a deaf lineage. The genes went to work in the auditory pathways of the mouse brains, creating light-sensitive patches on the membranes of their spiral ganglion neurons and other neurons. The scientists then directed LED light onto these neurons and recorded brain stem activity—an essential integration step in auditory processing.

Researchers build optical invisibility cloak for a diffusive medium

Researchers build optical invisibility cloak for a diffusive medium: ...The tank was filled with a white, turbid liquid. Objects inside cast a visible shadow onto the tank wall. Simple metal cylinders or spheres of a few centimeters in diameter were used as test objects... To pass the light around the object, the researchers applied a thin shell made of the transparent silicon material PDMS, to which a certain concentration of light-scattering melamine microparticles was added. The silicon/melamine shell caused a quicker diffusion than in the environment and, thus, passed the light around the objects...

"Ideal optical invisibility cloaks in air have a drawback... They violate Albert Einstein's theory of relativity that prescribes an upper limit for the speed of light.  In diffuse media, in which light is scattered several times, however, the effective speed of light is reduced. Here, ideal invisibility cloaks can be realized."

Continuous terahertz sources demonstrated at room temperature

Continuous terahertz sources demonstrated at room temperature: They have developed the first room-temperature, compact, continuous terahertz radiation source, and it's six times more efficient than previous systems...

The team generated terahertz radiation through nonlinear frequency mixing of two mid-infrared wavelengths at 8.8 microns and 9.8 microns from a single QCL chip. Room temperature, continuous terahertz emission with 3 microwatts is realized in a monolithic nonlinear QCL device with a tiny packaging dimension (as small as 2x5x8 mm3). This is achieved by improving the thermal conductance with epilayer-down bonding and a buried ridge waveguide, as well as by decreasing the optical loss with a buried composite grating for stable, single mode operation.

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI: The hyperbolic metamaterial behaves as a metal when light is passing through it in one direction and like a dielectric in the perpendicular direction. This “extreme anisotropy” leads to “hyperbolic dispersion” of light and the ability to extract many more photons from devices than otherwise possible, resulting in high performance...

The list of possible applications for metamaterials includes a “planar hyperlens” that could make optical microscopes 10 times more powerful and able to see objects as small as DNA, advanced sensors, more efficient solar collectors, and quantum computing.

Quantum Random Number Generator Created Using A Smartphone Camera� — The Physics arXiv Blog — Medium

Quantum Random Number Generator Created Using A Smartphone Camera� — The Physics arXiv Blog — Medium:  It’s straightforward to calculate the average number of electrons this process should produce, given the probabilistic nature of photon emission. But the actual number of electrons should differ by a number that is random. That produces a single random digit. And since a light-sensitive array consists of many pixels working in parallel, it is possible to generate a large quantity of random digits from each image...

So the process of generating random numbers consists of pointing the camera at a green LED that evenly illuminates all the pixels and pressing the shutter button. A simple program then extracts the random digits.

Genetic algorithm used to design broadband metamaterial | KurzweilAI

Genetic algorithm used to design broadband metamaterial | KurzweilAI: "...this is the first that can cover a super-octave [more than doubling] bandwidth in the infrared spectrum...”

The new metamaterial is actually made of layers on a silicon substrate or base. The first layer is palladium, followed by a polyimide (plastic) layer and a palladium screen layer on top. The screen has elaborate, complicated cutouts — sub-wavelength geometry — that serve to block the various wavelengths. A polyimide layer caps the whole absorber...

This evolved metamaterial can be easily manufactured because it is simply layers of metal or plastic that do not need complex alignment. The clear cap of polyimide serves to protect the screen, but also helps reduce any impedance mismatch that might occur when the wave moves from the air into the device...

Neuron Light Switch Now Goes “On” and “Off” | MIT Technology Review

Neuron Light Switch Now Goes “On” and “Off” | MIT Technology Review: Now, two research groups have engineered new optogenetic proteins that can be used to efficiently silence neurons... His group’s new “off” switch for neurons was created by changing 10 of the 333 amino acids in an existing optogenetic protein, which itself had been engineered by combining natural proteins from green algae. That advance “creates a powerful tool that allows neuroscientists to apply a brake in any specific circuit with millisecond precision...”

Micro-macro entangled 'cat states' could one day test quantum gravity

Micro-macro entangled 'cat states' could one day test quantum gravity: The proposed method involves storing one component of an entangled state of light (consisting of just one or a few photons) in a mechanical resonator (consisting of billions of atoms). During this process, the initial microscopic entangled state of photons is amplified with a strong coherent beam, the photons are converted into phonons, and then the entangled states are retrieved.
This approach makes it possible to create optomechanical "cat states," in which the quantum states of the photons and phonons are in superposition.

New ‘switch’ could power quantum computing | MIT News Office

New ‘switch’ could power quantum computing | MIT News Office:  “We have demonstrated basically an atom can switch the phase of a photon. And the photon can switch the phase of an atom...”

In this case, the researchers used a laser to place a rubidium atom very close to the surface of a photonic crystal cavity, a structure of light. The atoms were placed no more than 100 or 200 nanometers — less than a wavelength of light — from the edge of the cavity. At such small distances, there is a strong attractive force between the atom and the surface of the light field, which the researchers used to trap the atom in place...

“In some sense, it was a big surprise how simple this solution was compared to the different techniques you might envision of getting the atoms there,” Vuletić says.

How To Build A Quantum Telescope — Medium

How To Build A Quantum Telescope — Medium: Her idea is to use the astrophysical photons to stimulate the production of an entangled pair, inside a telescope. The first of this pair then hits the detector, generating an image. But the other can be used to increase the information known about the first, thereby increasing the resolution and beating the diffraction limit.

First glimpse of big bang ripples from universe's birth - physics-math - 17 March 2014 - New Scientist

First glimpse of big bang ripples from universe's birth - physics-math - 17 March 2014 - New Scientist: Inflation should have stretched the very first gravitational waves created during the big bang, taking them from imperceptible wavelengths to a size we can detect in the CMB... Rippling gravitational waves would subtly change the polarisation pattern, twisting the CMB into distinctive swirls called B-modes...

"We see a big excess of power, and it looks exactly like the gravitational wave signal that we had been seeking," says Pryke. "There's a huge zoo of inflationary models, but if we look at the simplest ones, they would predict values in the ballpark that we're seeing..."

"If gravity were not quantised, inflation would not produce gravitational waves," says Guth.