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Category: computing

Twisted bilayer photonic crystals dynamically tune light’s handedness

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have created a chip-scale device that can dynamically control the “handedness” of light as it passes through—also known as its optical chirality—with a simple twist of two specially designed photonic crystals. The study is published in the journal Optica.

The work, led by graduate student Fan Du in the lab of Eric Mazur, the Balkanski Professor of Physics and Applied Physics, describes a reconfigurable twisted bilayer photonic crystal that can be tuned in real time using an integrated micro-electromechanical system (MEMS). The breakthrough opens new possibilities for advanced chiral sensing, optical communication, and quantum photonics.

“Chirality is very important in many fields of science—from pharma to chemistry, biology, and of course, physics and photonics,” Mazur said. “By integrating twisted photonic crystals with MEMS, we have a platform that is not only powerful from a physics standpoint, but also compatible with the way modern photonics are manufactured.”

Photonic ‘ski jumps’ efficiently beam light into free space

Photonic chips use light to process data instead of electricity, enabling faster communication speeds and greater bandwidth. Most of that light typically stays on the chip, trapped in optical wires, and is difficult to transmit to the outside world in an efficient manner.

If a lot of light could be rapidly and precisely beamed off the chip, free from the confines of the wiring, it could open the door to higher-resolution displays, smaller Lidar systems, more precise 3D printers, or larger-scale quantum computers.

Now, researchers from MIT and elsewhere have developed a new class of photonic devices that enable the precise broadcasting of light from the chip into free space in a scalable way.

Acoustic driving enables controlled condensation of light and matter on chip

An international research team led by Alexander Kuznetsov at the Paul Drude Institute for Solid State Electronics (PDI) in Berlin has demonstrated a fundamentally new way to control the condensation of hybrid light-matter particles. Using coherent acoustic driving to dynamically reshape the energy landscape of a semiconductor microcavity, the researchers achieved deterministic steering of a macroscopic quantum state into its lowest energy configuration.

The results, published in Nature Photonics, establish a strategy for engineering nonequilibrium quantum states and open prospects for ultrafast, tunable photonic technologies.

In collaboration with long-term partners from the National Scientific and Technical Research Council CONICET and the Bariloche Atomic Center and Balseiro Institute in Argentina, the team experimentally realized a universal scheme for selectively transferring populations within a multilevel quantum system using strong time periodic modulation.

Simulations suggest a breakthrough in understanding how turbulence develops

A new study revisits a century-old question about how turbulence starts. The findings could potentially influence not only aircraft engineering but even the design of mechanical heart valves, and treatment of heart disease. The study is published in Scientific Reports.

Computer simulations at Stockholm’s KTH Royal Institute of Technology indicate that very small vortices may create increasingly larger swirls of flow—the opposite of the traditional view of how energy is transferred in turbulence.

Often seen in nature, from whirlpools to the shape of galaxies, vortices are one of the main flow structures that drive turbulence. The dominant idea over the last 100 years is that large swirling motions in a fluid break apart into smaller and smaller swirls, passing energy down the chain until it finally disappears—a process known as the forward cascade.

Space Weather Could Be Hiding Alien Signals

Dr. Vishal Gajjar: “If a signal gets broadened by its own star’s environment, it can slip below our detection thresholds, even if it’s there, potentially helping explain some of the radio silence we’ve seen in technosignature searches.”

What steps can be taken to identify why we haven’t received radio signals from an extraterrestrial intelligence, also called technosignatures? This is what a recent study published in The Astrophysical Journal hopes to address as a team of scientists investigated potential explanations regarding why humanity continues hearing silence from technosignatures. This study has the potential to help scientists and the public better understand the shortcomings and enhancements that can be made in the search for intelligent life beyond Earth.

For the study, the researchers used a series of computer models to simulate how radio signals leaving extrasolar star systems could be influenced by a myriad of factors, specifically space weather coming from the host star. This study comes as SETI and other researchers worldwide continue to come up empty regarding identifying technosignatures. The goal of the study was to ascertain potential reasons while putting constraints on both how and where to search for technosignatures.

In the end, the researchers ascertained that space weather plays a role in altering the outgoing radio signals by dispersing them, as opposed to the radio signals maintaining a fixed beam. The team ascertained that M-dwarf stars, which constitute approximately 75 percent of the stars in the Milky Way Galaxy while being smaller and cooler than our Sun, are prime targets for searching for technosignatures. This is due to their space weather, which is far more active than stars like our Sun, dispersing the radio signals.

Performance characteristics of genome-sequencing–based CHIP calling and impact on epidemiologic associations

Do we need better ways to detect clonal hematopoiesis of indeterminate potential (CHIP)?

In this Research Letter, Alexander G. Bick & team find epidemiology studies underestimate the strength of the association between clonal hematopoiesis and disease due to false negatives from shallow, whole-genome versus deep targeted sequencing.

Address correspondence to: Alexander Bick, 2,200 Pierce Ave., 550 RRB, Nashville, Tennessee, 37,232, USA. Email: alexander.bick@vumc.org.

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1Department of Internal Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

Ultrafast computing: Light-driven logic tops 10 terahertz in WS₂

The future for our computers will literally be at the speed of light. Extremely short light pulses can perform ultrafast logical operations: these are the findings of a study recently published in the journal Nature Photonics. The study represents an important step toward developing a new generation of information processing technologies, potentially hundreds of times faster than what we have at present.

Today’s computers rely on the movement of electrical charges inside transistors; however, these can only achieve a maximum frequency whose physical limits are hard to overcome. Unlike traditional electronics, based on the movement of electric charges, this innovative approach manipulates the state of electrons in matter by the use of oscillating light.

As Giulio Cerullo of the Politecnico di Milano explained, “We have shown that light can be used not only to transmit information, but also to process it. With the use of ultra-short laser pulses, we can control the quantum states of matter on time scales of a few millionths of a billionth of a second, i.e. at the same frequencies as light oscillations, speeds previously unknown in electronics.” These operations are performed at rates above 10 terahertz, over a hundred times faster than the best modern electronic devices.

Miniature laser technology could bring lab testing into your home

A research team at Chalmers University of Technology, Sweden, has developed new laser technology that could lead to tiny, cost-effective biosensors. The sensors integrate lasers and optics together on a centimeter-sized chip, which could move testing from hospitals to patients’ homes. This, in turn, would free up hospital beds and reduce visits to clinics.

The team’s study, “Flat Plasmonic Biosensor with an On-Chip Metagrating-Integrated Laser,” is published in ACS Sensors.

By studying how various biomolecules interact with each other—for example, antibodies in the immune system and xenobiotic antigens—researchers can gain valuable insights leading to new medicines and vaccines or assess whether a sample contains signs of infection.

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