March 11, 2019
Good Morning,
Austrian scientists have created an anti-laser because - "Why Not!?" What could this be used for? Could this help out humanity in any way? Will it be the MacGuffin in the next James Bond movie?
Learn about this and more interesting stories from the scientific community in today's issue.
Until Next Time,
Erin
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*-- Physicists build random anti-laser --*
Scientists in Austria have built the inverse of a laser, an anti-laser.
Lasers turns energy into a specific light frequency. The device developed by researchers at the Vienna University of Technology does the opposite, absorbing a specific color of light and scattering nearly all of the energy.
The anti-laser technology -- described this week in the journal Nature -- may offer applications in a variety of electronic and optical fields.
"Every day we are dealing with waves that are scattered in a complicated way -- think about a mobile phone signal that is reflected several times before it reaches your cell phone," Stefan Rotter, a professor at TU Vienna's Institute for Theoretical Physics, said in a news release. "The so-called random lasers make use of this multiple scattering. Such exotic lasers have a complicated, random internal structure and radiate a very specific, individual light pattern when supplied with energy."
Rotter and his colleagues used the logic of the laser and worked backwards, constructing a model that showed the inner structure of an anti-laser device could be designed to absorb a specific light frequency.
"Because of this time-reversal analogy to a laser, this type of absorber is called an anti-laser," said Rotter. "So far, such anti-lasers have only been realized in one-dimensional structures, which are hit by laser light from opposite sides. Our approach is much more general. We were able to show that even arbitrarily complicated structures in two or three dimensions can perfectly absorb a specially tailored wave. That way, the concept can be used for a wide range of applications."
More than just a light absorber, an anti-laser works to effectively dissipate the energy of the lightwaves it swallows up.
"There is a complex scattering process in which the incident wave splits into many partial waves, which then overlap and interfere with each other in such a way that none of the partial waves can get out at the end," Rotter said.
Researchers at TU Vienna teamed with scientists at the University of Nice in France to confirm the mathematical logic of the anti-laser and develop a strategy for turning the concept into an actual device.
The anti-laser consists of an absorbing antenna inside a microwave chamber. The chamber is surrounded by Teflon cylinders. The cylinders reflect the scattered light waves back toward each other, creating a complex frequency pattern.
Tests proved the device works as theorized.
"First we send microwaves from outside through the system and measure how exactly they come back," said researcher Kevin Pichler. "Knowing this, the inner structure of the random device can be fully characterized. Then it is possible to calculate the wave that is completely swallowed by the central antenna at the right absorption strength. In fact, when implementing this protocol in the experiment, we find an absorption of approximately 99.8 percent of the incident signal."
According to the device's creators, the technology could have a variety of applications, including uses in communication technologies and medicine.
"Imagine, for example, that you could adjust a cell phone signal exactly the right way, so that it is perfectly absorbed by the antenna in your cell phone," Rotter said. "Also in medicine, we often deal with the task of transporting wave energy to a very specific point -- such as shock waves shattering a kidney stone."
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*-- CERN reveals plans for new experiment to search for dark matter particles --*
Officials at CERN have approved a new experiment designed to identify light and weakly interacting particles. The Forward Search Experiment, FRASER, will compliment CERN's ongoing search for dark matter.
"It is very exciting to have FASER approved for installation at CERN," Jamie Boyd, a spokesperson for the FASER experiment, said in an update. "It is amazing how the collaboration has come together so quickly and we are looking forward to recording our first data when the LHC starts up again in 2021."
For the experiment, scientists will assemble and install a new instrument inside the Large Hadron Collider at CERN, the European Council for Nuclear Research. It is the largest and most powerful particle collider in the world.
The project was initiated by a team of physicists at the University of California, Irvine.
"Seven years ago, scientists discovered the Higgs boson at the Large Hadron Collider, completing one chapter in our search for the fundamental building blocks of the universe, but now we are looking for new particles," Jonathan Feng, UCI professor of physics and astronomy, said in a news release. "The dark matter problem shows that we don't know what most of the universe is made of, so we're sure new particles are out there."
Feng and his colleagues at UCI will collaborate with scientists from Europe, China and Japan, as well with physicists from other universities in the United States. In total, the new dark matter experiment will involve the efforts of 30 to 40 researchers.
The FASER instrument is a small device that will be placed near the collider's massive underground tunnel, a 16-mile loop. The device will be positioned near the ATLAS instrument, which produces subatomic particles as protons pass through.
Scientists hope that the ATLAS instrument will create new exotic particles that can be measured by the FASER instrument as they decay.
"One of the advantages of our design is that we've been able to borrow many of the components of FASER -- silicon detectors, calorimeters and electronics -- from the ATLAS and LHCb collaborations," Boyd said. "That's allowing us to assemble an instrument that costs almost hundreds of times less than the largest experiments at the LHC."
Every time LHC and ATLAS conduct particle collision experiments in 2021 and 2023, the FASER instrument will be collecting data that could reveal the presence of "dark photons," particles associated with dark matter, neutralinos and other exotic particles.
The FASER instrument will be one of eight instruments currently looking for undiscovered particles in the collider. In effort to find exotic particles associated with dark matter, CERN has worked to incorporate new technologies as part of the Physics Beyond Collider study.
"This novel experiment helps diversify the physics program of colliders such as the LHC, and allows us to address unanswered questions in particle physics from a different perspective," said Mike Lamont, co-coordinator of the PBC study group.
The collider's main detectors aren't designed to identify light and weakly interacting particles. Exotic particles produced by ATLAS could go undetected, traveling through the tunnel for hundred of feet, parallel to the main beam line, before turning back into more common particles.
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