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Category: quantum physics – Page 272
Never let it be said that scientists don’t have an eye for the sublime.
Encoding and deciphering a Chinese symbol for duality and harmony into the quantum states of two entangled photons, physicists recently demonstrated the superior efficiency of a new analytical technique.
Researchers from the Sapienza University of Rome and the University of Ottawa in Canada used a method similar to a popular holographic technique to quickly and reliably measure information of a particle’s position.
Quantum technology’s future rests on the exploitation of fascinating quantum mechanics concepts—such as high-dimensional quantum states. Think of these states as basic ingredients of quantum information science and quantum tech. To manipulate these states, scientists have turned to light, specifically a property called orbital angular momentum (OAM), which deals with how light twists and turns in space. Here’s a catch: making super bright single photons with OAM in a deterministic fashion has been a tough nut to crack.
Now, enter quantum dots (QDs), tiny particles with big potential. A team of researchers from Sapienza University of Rome, Paris-Saclay University, and University of Naples Federico II combined the features of OAM with those of QDs to create a bridge between two cutting-edge technologies.
Their results are published in Advanced Photonics.
Does hot water freeze faster than cold water? Aristotle may have been the first to tackle this question that later became known as the Mpemba effect.
This phenomenon originally referred to the non-monotonic initial temperature dependence of the freezing start time, but it has been observed in various systems — including colloids — and has also become known as a mysterious relaxation phenomenon that depends on initial conditions.
However, very few have previously investigated the effect in quantum systems.
Year 2022 Infinite quantum computer :3.
The scaling of the entanglement entropy at a quantum critical point allows us to extract universal properties of the state, e.g., the central charge of a conformal field theory. With the rapid improvement of noisy intermediate-scale quantum (NISQ) devices, these quantum computers present themselves as a powerful tool to study critical many-body systems. We use finite-depth quantum circuits suitable for NISQ devices as a variational ansatz to represent ground states of critical, infinite systems. We find universal finite-depth scaling relations for these circuits and verify them numerically at two different critical points, i.e., the critical Ising model with an additional symmetry-preserving term and the critical XXZ model.
For years, researchers have tried various ways to coax quantum bits—or qubits, the basic building blocks of quantum computers—to remain in their quantum state for ever-longer times, a key step in creating devices like quantum sensors, gyroscopes, and memories.
A team of physicists from MIT have taken an important step forward in that quest, and to do it, they borrowed a concept from an unlikely source—noise-cancelling headphones.
Led by Ju Li, the Battelle Energy Alliance Professor in Nuclear Engineering and professor of materials science and engineering, and Paola Cappellaro, the Ford Professor of Engineering in the Department of Nuclear Science and Engineering and Research Laboratory of Electronics, and a professor of physics, the team described a method to achieve a 20-fold increase in the coherence times for nuclear-spin qubits.
Tiny dents on thin material produce photon-polarizing magnetic fields.
Researchers at Los Alamos National Laboratory have developed a technique that can produce polarized photons more easily and cheaply than existing methods. The technique.
Quantum communication uses photons to carry information, much as classical communication uses electrons. But while classical computers encode information by turning current… More.
Dias didn’t disappoint. He and his colleagues had created a material — lutetium mixed with nitrogen and hydrogen, or LuNH — that was a superconductor at room temperature, he announced.
That claim, which the scientists published in Nature the next day1, would have been historic — if true. Superconductors conduct electricity with zero resistance, meaning that no energy is lost as heat. But they usually work only at very low temperatures, well below −100 °C, so need expensive refrigeration. This limits their use to niche applications, such as magnetic resonance imaging scans and quantum computing. A superconducting material that needs no cooling could potentially transform electricity generation and transmission, transportation and a slew of other applications.
Dias’s claim was remarkable not only for the material’s balmy operating temperature of 21 °C (294 K), but also because it required comparatively modest pressures. Other teams working with hydrogen compounds, called hydrides, have observed superconductivity at high temperatures, but had to squeeze their samples to hundreds of gigapascals (GPa) — millions of times more than atmospheric pressure. Dias, by contrast, said that his hydride needed just 1 GPa (10,000 times atmospheric pressure): still impractical for real-world applications, but a striking advance. A patent application for LuNH, released in April, goes further, claiming superconductivity at room temperature and pressure.
Scientists with the University of Chicago have demonstrated a way to create infrared light using colloidal quantum dots. The researchers said the method demonstrates great promise; the dots are already as efficient as existing conventional methods, even though the experiments are still in early stages.
The dots could someday form the basis of infrared lasers as well as small and cost-effective sensors, such as those used in exhaust emissions tests or breathalyzers.
“Right now the performance for these dots is close to existing commercial infrared light sources, and we have reason to believe we could significantly improve that,” said Philippe Guyot-Sionnest, a professor of physics and chemistry at the University of Chicago, member of the James Frank Institute, and one of three authors on the paper published in Nature Photonics. “We’re very excited for the possibilities.”