One of the most fundamental interactions in physics is that of electrons and light. In an experiment at Goethe University Frankfurt, scientists have now managed to observe what is known as the Kapitza-Dirac effect for the first time in full temporal resolution. This effect was first postulated more than 90 years ago, but only now are its finest details coming to light.
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.
Machine learning revolutionizes secure quantum communication, pushing its boundaries to unprecedented frontiers.
Researchers at Fudan University in China have recently been trying to identify new promising quantum anomalous Hall insulators. Their latest paper, published in Physical Review Letters, outlines the unique characteristics of monolayer V2MX4, which could belong to a new family of quantum anomalous Hall insulators.
“Finding intrinsic quantum anomalous Hall materials is an important goal in topological material research,” Jing Wang, co-author of the paper, told Phys.org. “After we predicted MnBi2Te4, a paradigm example of magnetic topological insulator and exhibiting quantum anomalous Hall effect in odd layer, we have been thinking about finding new intrinsic quantum anomalous Hall insulator with large gap.”
Large-gap quantum anomalous Hall insulator materials exhibit a quantum anomalous Hall effect with a relatively large energy gap between the valence and conduction band. These materials should exhibit a synergy between two seemingly conflicting properties, namely spin-orbit coupling and ferromagnetism.
Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.
In recent years, artificial intelligence technologies, especially machine learning algorithms, have made great strides. These technologies have enabled unprecedented efficiency in tasks such as image recognition, natural language generation and processing, and object detection, but such outstanding functionality requires substantial computational power as a foundation.
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.
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.
Caltech research shows Barkhausen noise in magnets can also arise from quantum mechanics, not just classical methods.
Researchers made quantum processors warmer and improve their efficiency.
Engineers from the University of New South Wales have achieved a new milestone in physics.
Researchers from the University of New South Wales made quantum processors warmer and improved their efficiency.