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Category: particle physics – Page 186

Electrically Tunable Metasurfaces: Liquid Crystal Alignment by Dielectric Meta-Atoms

Dielectric metasurfaces, known for their low loss and subwavelength scale, are revolutionizing optical systems by allowing multidimensional light modulation. Researchers have now innovated in this field by developing a liquid crystal-based dielectric metasurface that streamlines manufacturing and enhances device performance.

Dielectric metasurfaces represent one of the cutting-edge research and application directions in the current optical field. They not only possess the advantage of low loss but also enable the realization of device thicknesses at subwavelength scales. Moreover, they can freely modulate light in multiple dimensions such as amplitude, phase, and polarization. This capability, which traditional optics lacks, holds significant importance for the integration, miniaturization, and scaling of future optical systems. Consequently, dielectric metasurfaces have attracted increasing industrial attention.

In this study, Professor Daping Chu’s team at the University of Cambridge developed a novel liquid crystal-based tunable dielectric metasurface. By leveraging the dielectric metasurface’s inherent alignment effect on liquid crystals on top of its electrically controllable properties, the need for liquid crystal alignment layer materials and related processes is eliminated, thus saving device manufacturing time and costs. This has practical implications for devices such as liquid crystal on silicon (LCoS).

Reimagining quantum dot single-photon sources: A breakthrough in monolithic Fabry-Perot microcavities

Self-assembled semiconductor quantum dots (QDs) represent a three-dimensional confined nanostructure with discrete energy levels, which are similar to atoms. They are capable of producing highly efficient and indistinguishable single photons on demand and are important for exploring fundamental quantum physics and various applications in quantum information technologies. Leveraging traditional semiconductor processes, this material system also offers a natural integration-compatible and scalable platform.

Quantum Leap: Redefining Complex Problem-Solving

The traveling salesman problem is considered a prime example of a combinatorial optimization problem. Now a Berlin team led by theoretical physicist Prof. Dr. Jens Eisert of Freie Universität Berlin and HZB has shown that a certain class of such problems can actually be solved better and much faster with quantum computers than with conventional methods.

Quantum computers use so-called qubits, which are not either zero or one as in conventional logic circuits, but can take on any value in between. These qubits are realized by highly cooled atoms, ions, or superconducting circuits, and it is still physically very complex to build a quantum computer with many qubits. However, mathematical methods can already be used to explore what fault-tolerant quantum computers could achieve in the future.

“There are a lot of myths about it, and sometimes a certain amount of hot air and hype. But we have approached the issue rigorously, using mathematical methods, and delivered solid results on the subject. Above all, we have clarified in what sense there can be any advantages at all,” says Prof. Dr. Jens Eisert, who heads a joint research group at Freie Universität Berlin and Helmholtz-Zentrum Berlin.

Can Matrioshka brains run simulated universes to the subatomic level?

The advanced civilization in my story have harnessed the power of many of the stars in their galaxy and using them for different purposes, one being Matrioska brains. Some of these super computers will be to run the AI in the real world as well as for other calculations, Others will be to run detailed virtual worlds. The earliest Simulations will be Computer simulated worlds with artifical life within but later the advanced species will try to create simulations to the subatomic level.

It has been stated that a Matrioshka brain with the full output of the sun can simulate 1 trillion to a quadrillion minds, how this translates to how much world/simulation space can exist and to what detail i am not sure. I believe our sun’s output per second is $3.86 \cdot 10^{26}$ W and our galaxies is $4\cdot 10^{58} \ W/s$, although with 400 billions stars in our galaxy I am not sure how of that energy is from other sources than the stars.

If we look past the uncertainty of subatomic partcles we have $10^{80}$ particles in a space of $10^{185}$ plank volumes in our observable universe, if we use time frames of $10^{-13}$ seconds this gives $10^{13}$ time frames per real second. With $10^{80}$ particles we can have $10^{160}$ interactions for a full simulation but a simulation where only the observed/ observable details needs to be simulated can run off much less computing.

Physicists steer chemical reactions by magnetic fields and quantum interference

Physicists in the MIT-Harvard Center for Ultracold Atoms (CUA) have developed a new approach to control the outcome of chemical reactions. This is traditionally done using temperature and chemical catalysts, or more recently with external fields (electric or magnetic fields, or laser beams).

MIT CUA physicists have now added a new twist to this: They have used minute changes in a magnetic field to make subtle changes to the quantum mechanical wavefunction of the colliding particles during the chemical reaction. They show how this technique can steer reactions to a different outcome: enhancing or suppressing reactions.

This was only possible by working at ultralow temperatures at a millionth of a degree above absolute zero, where collisions and chemical reactions occur in single quantum states. Their research was published in Science on March 4.

Decoding Earth’s Cosmic Shields in Groundbreaking Study

New insights into near-Earth space’s hazardous environment could revolutionize space weather prediction, driven by collaborative international research.

A challenge to space scientists to better understand our hazardous near-Earth space environment has been set in a new study led by the University of Birmingham.

The research represents the first step towards new theories and methods that will help scientists predict and analyze the behavior of particles in space. It has implications for theoretical research, as well as for practical applications such as space weather forecasting.

From Theory to Reality: Graviton-like Particles Found in Quantum Experiments

The results, continuing the legacy of late Columbia professor Aron Pinczuk, are a step toward a better understanding of gravity.

A team of scientists from Columbia, Nanjing University, Princeton, and the University of Munster, writing in the journal Nature, have presented the first experimental evidence of collective excitations with spin called chiral graviton modes (CGMs) in a semiconducting material.

A CGM appears to be similar to a graviton, a yet-to-be-discovered elementary particle better known in high-energy quantum physics for hypothetically giving rise to gravity, one of the fundamental forces in the universe, whose ultimate cause remains mysterious.