Archive for the ‘quantum physics’ category: Page 4

Freeze laser.

We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of $\overline{n}=0.13$ after sideband cooling, corresponding to a ground-state occupation probability of 88%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the $|n=0⟩$ and $|n=1⟩$ Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system.

A collaboration between researchers from The University of Western Australia and The University of California Merced has provided a new way to measure tiny forces and use them to control objects.

The research, published recently in Nature Physics, was jointly led by Professor Michael Tobar, from UWA’s School of Physics, Mathematics and Computing and Chief Investigator at the Australian Research Council Centre of Excellence for Engineered Quantum Systems and Dr. Jacob Pate from the University of Merced.

Professor Tobar said that the result allowed a new way to manipulate and control macroscopic objects in a non-contacting way, allowing enhanced sensitivity without adding loss.

A team of physicists led by Professor Patrick Windpassinger at Johannes Gutenberg University Mainz (JGU) has successfully transported light stored in a quantum memory over a distance of 1.2 millimeters. They have demonstrated that the controlled transport process and its dynamics has only little impact on the properties of the stored light. The researchers used ultra-cold rubidium-87 atoms as a storage medium for the light as to achieve a high level of storage efficiency and a long lifetime.

“We stored the light by putting it in a suitcase so to speak, only that in our case the suitcase was made of a cloud of cold atoms. We moved this suitcase over a short distance and then took the light out again. This is very interesting not only for physics in general, but also for , because light is not very easy to ‘capture’, and if you want to transport it elsewhere in a controlled manner, it usually ends up being lost,” said Professor Patrick Windpassinger, explaining the complicated process.

The controlled manipulation and storage of quantum information as well as the ability to retrieve it are essential prerequisites for achieving advances in quantum communication and for performing corresponding computer operations in the quantum world. Optical quantum memories, which allow for the storage and on-demand retrieval of quantum information carried by light, are essential for scalable quantum communication networks. For instance, they can represent important building blocks of quantum repeaters or tools in linear quantum computing. In recent years, ensembles of atoms have proven to be media well suited for storing and retrieving optical quantum information. Using a technique known as electromagnetically induced transparency (EIT), incident light pulses can be trapped and coherently mapped to create a collective excitation of the atoms. Since the process is largely reversible, the light can then be retrieved again with high efficiency.

The Higgs mode associated with the amplitude fluctuation of an order parameter can decay into other low-energy bosonic modes, which renders the Higgs mode usually unstable in condensed matter systems. Here, the authors propose a mechanism to stabilize the Higgs mode in anisotropic quantum magnets. They show that magnetic anisotropy gaps out the Goldstone magnon mode and stabilizes the Higgs mode near a quantum critical point. The results are supported by three independent approaches: a bond-operator method, field theory, and quantum Monte Carlo simulation with analytic continuation.

Caltech’s OrbNet deep learning tool outperforms state-of-the-art solutions.

Artificial intelligence (AI) machine learning is being applied to help accelerate the complex science of quantum mechanics—the branch of physics that studies matter and light on the subatomic scale. Recently a team of scientists at the California Institute of Technology (Caltech) published a breakthrough study in The Journal of Chemical Physics that unveils a new machine learning tool called OrbNet that can perform quantum chemistry computations 1,000 times faster than existing state-of-the-art solutions.

“We demonstrate the performance of the new method for the prediction of molecular properties, including the total and relative conformer energies for molecules in range of datasets of organic and drug-like molecules,” wrote the researchers.

Physics theory suggests that exotic excitations can exist in the form of bound states confined in the proximity of topological defects, for instance, in the case of Majorana zero modes that are trapped in vortices within topological superconducting materials. Better understanding these states could aid the development of new computational tools, including quantum technologies.

One phenomenon that has attracted attention over the past few years is “braiding,” which occurs when electrons in particular states (i.e., Majorana fermions) are braided with one another. Some physicists have theorized that this phenomenon could enable the development of a new type of quantum technology, namely topological quantum computers.

Researchers at Pennsylvania State University, University of California-Berkeley, Iowa State University, University of Pittsburgh, and Boston University have recently tested the hypothesis that braiding also occurs in particles other than electrons, such as photons (i.e., particles of light). In a paper published in Nature Physics, they present the first experimental demonstration of braiding using photonic topological zero modes.

International Business Machines, still the legal name of century-plus-old IBM, has managed over the years to pull off a dubious feat. Despite selling goods and services in one of the most dynamic industries in the world, the IT sector the company helped create, it has managed to avoid growing.

The company that was synonymous with mainframes, that dominated the early days of the personal computer (a “PC” once meant a device that ran software built to IBM’s technical standards), and that reinvented itself as a tech-consulting goliath, lagged while upstarts and a few of its old competitors zoomed past it.

What IBM excelled at more often was marketing a version of its aspirational self. Its consultants would advise urban planners on how to create “smart cities.” Its command of artificial intelligence, packaged into a software offering whose name evoked its founding family, would cure cancer. Its CEO would wow the Davos set with cleverly articulated visions of how corporations could help fix the ills of society.

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This could be important!

A new algorithm that fast forwards simulations could bring greater use ability to current and near-term quantum computers, opening the way for applications to run past strict time limits that hamper many quantum calculations.

“Quantum computers have a limited time to perform calculations before their useful quantum nature, which we call coherence, breaks down,” said Andrew Sornborger of the Computer, Computational, and Statistical Sciences division at Los Alamos National Laboratory, and senior author on a paper announcing the research. “With a we have developed and tested, we will be able to fast forward quantum simulations to solve problems that were previously out of reach.”

Quantum mechanics, the physics of atoms and subatomic particles, can be strange, especially compared to the everyday physics of Isaac Newton’s falling apples. But this unusual science is enabling researchers to develop new ideas and tools, including quantum computers, that can help demystify the quantum realm and solve complex everyday problems.

That’s the goal behind a new U.S. Department of Energy Office of Science (DOE-SC) grant, awarded to Michigan State University (MSU) researchers, led by physicists at Facility for Rare Isotope Beams (FRIB). Working with Los Alamos National Laboratory, the team is developing algorithms – essentially programming instructions – for quantum computers to help these machines address problems that are difficult for conventional computers. For example, problems like explaining the fundamental quantum science that keeps an atomic nucleus from falling apart.

The \$750,000 award, provided by the Office of Nuclear Physics within DOE-SC, is the latest in a growing list of grants supporting MSU researchers developing new quantum theories and technology.

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