Lifeboat Foundation

Using laser light, researchers have developed the most robust method currently known to control individual qubits made of the chemical element barium. The ability to reliably control a qubit is an important achievement for realizing future functional quantum computers.

The paper, “A guided light system for agile individual addressing of Ba⁺ qubits with 10⁻⁴ level intensity crosstalk,” was published in Quantum Science and Technology.

This new method, developed at the University of Waterloo’s Institute for Quantum Computing (IQC), uses a small glass waveguide to separate laser beams and focus them four microns apart, about four-hundredths of the width of a single human hair. The precision and extent to which each focused laser beam on its target qubit can be controlled in parallel is unmatched by previous research.

A team of scientists with the Department of Energy’s Oak Ridge National Laboratory has investigated the behavior of hafnium oxide, or hafnia, because of its potential for use in novel semiconductor applications.

Materials such as hafnia exhibit ferroelectricity, which means that they are capable of extended data storage even when power is disconnected and that they might be used in the development of new, so-called nonvolatile memory technologies. Innovative nonvolatile memory applications will pave the way for the creation of bigger and faster computer systems by alleviating the heat generated from the continual transfer of data to short-term memory.

The scientists explored whether the atmosphere plays a role in hafnia’s ability to change its internal electric charge arrangement when an external electric field is applied. The goal was to explain the range of unusual phenomena that have been obtained in hafnia research. The team’s findings were recently published in Nature Materials. The title of the paper is “Ferroelectricity in hafnia controlled via surface electrochemical state.”

Researchers at Max Planck Institute of Quantum Optics (MPQ) and Technical University of Munich (TUM) demonstrated a potential platform for large-scale quantum computing and communication networks. Secure quantum networks are of interest to financial institutions, medical facilities, government agencies, and other organizations that handle personal data and classified information due to their much higher level of security.

To create an environment that supported quantum computing, the researchers excited individual atoms of the rare-earth metal erbium. The excitation process caused the erbium atoms to emit single photons with properties suitable for the construction of quantum networks.

Quantum computing has the potential to revolutionize the world, allowing massive health and science computation problems to be solved exponentially faster than by classic computing. But quantum computers have a big drawback—they can only operate in subzero temperatures.

“In order to make quantum computers work, we cannot use them at room temperature,” said Ahmed El-Gendy, Ph.D., an associate professor of physics at The University of Texas at El Paso. “That means we will need to cool the computers and cool all the materials, which is very expensive.”

Now, physicists at The University of Texas at El Paso believe they have made a quantum leap in that regard. Led by El-Gendy, the team has developed a highly magnetic quantum computing material—100 times more magnetic than pure iron—that functions at regular temperature. The material is described in a summer issue of the journal Applied Physics Letters.

Researchers at the University of Stuttgart have demonstrated that a key ingredient for many quantum computation and communication schemes can be performed with an efficiency that exceeds the commonly assumed upper theoretical limit—thereby opening up new perspectives for a wide range of photonic quantum technologies.

Quantum science has not only revolutionized our understanding of nature—it is also inspiring groundbreaking new computing, communication and sensor devices. Exploiting quantum effects in such “quantum technologies” typically requires a combination of deep insight into the underlying quantum-physical principles, systematic methodological advances, and clever engineering.

And it is precisely this combination that researches in the group of Prof. Stefanie Barz at the University of Stuttgart and the Center for Integrated Quantum Science and Technology (IQST) have delivered in a recent study, in which they have improved the efficiency of an essential building block of many quantum devices beyond a seemingly inherent limit. The work is published in the journal Science Advances.

Poor battery life is the favorite complaint when it involves smartphones and laptops. As a wireless society, having to tether ourselves right down to power up our gadgets seems more and more a nuisance. And while researchers are looking into wireless charging, if batteries were better we might worry less.

Now, a brand new technology promises just that. Researchers from the University of California, Irvine, have invented a nanowire-based battery that may be recharged many thousands of times, a big leap towards a battery that doesn’t require replacing.

Quantum computers can solve certain computational problems much faster than ordinary computers by using specific quantum properties. The basic building blocks of such machines are called quantum-bits or qubits. Qubits can be realized using several physical platforms such as nuclear spins, trapped ions, cold atoms, photons, and using superconducting Josephson circuits.

Several such qubits operate in the microwave frequency domain, and require specialized room temperature microwave electronics for control and readout of the quantum states of the qubits. However, there lies a challenge when it comes to connecting classical electronics to these qubits. The qubits need high frequency (GHz) electromagnetic signals for control and readout pulses in the order of a few tens of nanoseconds.

The traditional setup for generation and capture of such signals is often costly and complex with many components. This can be addressed by developing a specific FPGA-based system that brings the functionality of all the traditional equipment on to a single board. However, with such developments, three main challenges need to be kept in mind: generation and capture of the high-fidelity microwave signals, scalability, and a user-friendly interface.

Mixing and matching various strands of DNA can create versatile biological computer circuits that can take the square roots of numbers or solve quadratic equations.

By Karmela Padavic-Callaghan

A new set of equations captures the dynamical interplay of electrons and vibrations in crystals and forms a basis for computational studies.

Although a crystal is a highly ordered structure, it is never at rest: its atoms are constantly vibrating about their equilibrium positions—even down to zero temperature. Such vibrations are called phonons, and their interaction with the electrons that hold the crystal together is partly responsible for the crystal’s optical properties, its ability to conduct heat or electricity, and even its vanishing electrical resistance if it is superconducting. Predicting, or at least understanding, such properties requires an accurate description of the interplay of electrons and phonons. This task is formidable given that the electronic problem alone—assuming that the atomic nuclei stand still—is already challenging and lacks an exact solution. Now, based on a long series of earlier milestones, Gianluca Stefanucci of the Tor Vergata University of Rome and colleagues have made an important step toward a complete theory of electrons and phonons [1].

At a low level of theory, the electron–phonon problem is easily formulated. First, one considers an arrangement of massive point charges representing electrons and atomic nuclei. Second, one lets these charges evolve under Coulomb’s law and the Schrödinger equation, possibly introducing some perturbation from time to time. The mathematical representation of the energy of such a system, consisting of kinetic and interaction terms, is the system’s Hamiltonian. However, knowing the exact theory is not enough because the corresponding equations are only formally simple. In practice, they are far too complex—not least owing to the huge number of particles involved—so that approximations are needed. Hence, at a high level, a workable theory should provide the means to make reasonable approximations yielding equations that can be solved on today’s computers.