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Category: energy

Seeing the invisible: The limits of two-photon vision

Near-infrared light is invisible to humans. And yet, under the right conditions, the human eye can perceive it. Researchers from Poland’s International Center for Translational Eye Research (ICTER) have now shown that the efficiency of this phenomenon depends not only on the laser pulse itself, but also on two highly specific factors: the beam diameter and the precise focusing of light on the retina. The research is published in the journal Optics Letters.

In everyday life, we see visible light—wavelengths detected by the photoreceptors of the retina. Near-infrared light lies outside this range, which is why it normally remains invisible to us. However, for several years, scientists have known of an exception.

This exception is known as two-photon vision. In this phenomenon, a photopigment in the retina absorbs two infrared photons almost simultaneously. Each photon individually carries too little energy to trigger visual perception, but together they can initiate the process of vision. This is why, under certain conditions, humans can “see” radiation that theoretically should remain invisible.

Prickly pear cacti show promise as the building materials of tomorrow

Researchers from the University of Bath’s Department of Mechanical Engineering have shown that agricultural waste from prickly pear cactus plants could be used as a low-cost, low-carbon reinforcement for construction materials, offering a more sustainable alternative to conventional composites. The research is published in the Journal of Natural Fibers.

Composite materials combine strong reinforcing fibers with a lightweight base material, known as a matrix. Widely used composites like carbon fiber, fiberglass or Kevlar rely on synthetic fibers and energy-intensive manufacturing processes. Their durability also makes them difficult to reuse or recycle at the end of their lifespan. Swapping synthetic fibers with natural alternatives offers a renewable and biodegradable solution.

Matt Hutchins, a researcher in the Department of Mechanical Engineering and lead author of the study, said, “Inside the flat cactus pads is a naturally occurring fiber network. These fibers form a honeycomb-like structure that helps the plant support its own weight and resists bending in strong winds. We’re exploring how to extract these structures and keep them intact, borrowing their natural properties to reinforce bio-based composites.”

Good vibrations for quantum communications: Engineers couple single phonon to single atomic spin

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated, for the first time, a single quantum of vibrational energy interacting with a single atomic spin, seeding a pathway to quantum technologies that use sound as an information carrier, instead of light or electricity. The results are published in Nature.

Led by Marko Lončar, the Tiantsai Lin Professor of Electrical Engineering, the researchers engineered a nanometer-scale mechanical resonator around a single color-center spin qubit in diamond. These color centers, atomic defects in the diamond’s crystal structure, act as quantum memory capable of storing quantum information. The researchers’ new system can host sufficiently strong spin-phonon interactions for quantum information storage—a key challenge thus far in the field.

“At the heart of the experiment is a phonon—the smallest possible unit of sound,” Lončar said. “When we listen to music, it takes countless phonons working together to move our eardrums and maybe even get us spinning on the dance floor. But qubits are far more sensitive: a single phonon can be enough to change their quantum state—to excite them, or, as in our experiment, to help them relax.”

Quantum battery charges in a quadrillionth of a second with a laser — larger prototypes could last for years after charging for just a minute

This allows all molecules within the battery to charge at a constant speed, no matter its size. The more molecules involved, the more efficiently energy is absorbed throughout the system, meaning charging times actually decrease in real terms as the battery size increases.

“Similar to conventional batteries, quantum batteries charge, store and discharge energy,”, explained Hutchinson in the statement. “But while everyday batteries rely on chemical reactions, quantum batteries leverage properties of quantum mechanics. The advantage of quantum is that the system absorbs light in a single, giant ‘super absorption’ event and this charges the battery faster.”

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