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Scientists at the University of Groningen used a silver sawtooth nanoslit array to produce valley-coherent photoluminescence in two-dimensional tungsten disulfide flakes at room temperature. Until now, this could only be achieved at very low temperatures. Coherent light can be used to store or transfer information in quantum electronics. This plasmon-exciton hybrid device is promising for use in integrated nanophotonics (light-based electronics). The results were published in Nature Communications on 5 February.

Tungsten disulfide has interesting electronic properties and is available as a 2-D material. “The electronic structure of monolayer tungsten disulfide shows two sets of lowest energy points or valleys,” explains Associate Professor Justin Ye, head of the Device Physics of Complex Materials group at the University of Groningen. One possible application is in photonics, as it can emit light with valley-dependent circular polarization—a new degree of freedom to manipulate information. However, valleytronics requires coherent and polarized light. Unfortunately, previous work showed that photoluminescence polarization in tungsten disulfide is almost random at room temperature.

A team of chemists, engineers, material scientists and physicists from Princeton University, Rutgers University and the University of Regensburg has developed a chemical exfoliation technique to produce single-molecule-thick tungsten disulfide ink. The group describes their technique in a paper published in the journal Science Advances.

As research continues into the creation of truly useful quantum computers, scientists continue to search for new materials that could support such machines. In this new effort, the research team looked into finding ways to print very cold circuits inside quantum computers using superconducting ink.

The new method involved a material consisting of layers of tungsten disulfide and potassium. The researchers exfoliated the material by dunking it into a sulfuric acid solution. This dissolved the potassium and left behind single-molecule layers of tungsten disulfide. The final step involved rinsing the acid and remnants in it, leaving the layers of tungsten suspended in a tub of water. In this state, the researchers found that the layers of tungsten disulfide could be used as a form of ink that could be printed onto various types of surfaces, such as plastic, silicon or glass. This left a one-molecule-thick coating on the material.

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology, report physicists at the University of Basel and Ruhr-University Bochum in the journal Nature.

Quantum physics describes photons as light particles. Achieving an interaction between a single photon and a single atom is a huge challenge due to the tiny size of the atom. However, sending the photon past the atom several times by means of mirrors significantly increases the probability of an interaction.

In order to generate photons, the researchers use artificial atoms, known as quantum dots. These semiconductor structures consist of an accumulation of tens of thousands of atoms, but behave much like a single atom: when they are optically excited, their energy state changes and they emit a photon. “However, they have the technological advantage that they can be embedded in a semiconductor chip,” says Dr. Daniel Najer, who conducted the experiment at the Department of Physics at the University of Basel.

Supercomputers and quantum computers are potent tools for handling difficult calculations, problem-solving, and data analysis. Although they both have the potential to transform computing technology, their speeds and capacities differ greatly.

Supercomputers quickly process massive volumes of data to provide a single result using a conventional computing strategy with numerous processors. These computers are the most powerful in terms of raw computing speed, but they can only do one task at a time, and Moore’s Law places a cap on how much data they can process (the principle that computer processor speeds double every two years).

Quantum computers, on the other hand, utilize laws of quantum mechanics to process information in ways that regular computers cannot, resulting in vastly higher processing speeds. They can manage several activities at once and take on challenging issues that would take supercomputer months to resolve. Yet, because of their great sensitivity to temperature fluctuations and need for isolation from outside influences, quantum computers require more upkeep than their conventional equivalents.

In a mind-warping milestone experiment, scientists have been able to manipulate small numbers of individual photons of light, opening doors for the development of quantum technologies. This research, published in the journal Nature Physics on March 20, describes how the researchers were able to make two photons of light interact and measure the difference between these interacting photons and a single photon.

A new class of dynamical instabilities generated by a stable photonic lattice Hamiltonian and stable dissipative pairing interaction is sensitive to wavefunction localization and allows selective excitation and entanglement of pure topological photonic edge states with minimal resources.

Photosynthesis drives all life on Earth. Complex processes are required for the sunlight-powered conversion of carbon dioxide and water to energy-rich sugar and oxygen. These processes are driven by two protein complexes, photosystems I and II. In photosystem I, sunlight is used with an efficiency of almost 100%. Here a complex network of 288 chlorophylls plays the decisive role.

A team led by LMU chemist Regina de Vivie-Riedle has now characterized these chlorophylls with the help of high-precision quantum chemical calculations—an important milestone toward a comprehensive understanding of energy transfer in this system. This discovery may help exploit its efficiency in artificial systems in the future.

The chlorophylls in photosystem I capture sunlight in an antenna complex and transfer the energy to a reaction center. There, the solar energy is used to trigger a redox process—that is to say, a chemical process whereby electrons are transferred. The quantum yield of photosystem I is almost 100%, meaning that almost every absorbed photon leads to a redox event in the reaction center.

Researchers have discovered a way to “translate” quantum information between different kinds of quantum technologies, with significant implications for quantum computing, communication, and networking.

The research was published in the journal Nature on Wednesday. It represents a new way to convert quantum information from the format used by quantum computers to the format needed for quantum communication.

Photons—particles of light—are essential for quantum information technologies, but different technologies use them at different frequencies. For example, some of the most common quantum computing technology is based on superconducting qubits, such as those used by tech giants Google and IBM; these qubits store quantum information in photons that move at microwave frequencies.

The researchers observed it stimulated light emission, which Einstein predicted in 1916, in single photons for the first time.

A team of researchers from the University of Basel and the University of Sydney accomplished a groundbreaking feat by demonstrating the capability to manipulate and identify small numbers of interacting packets of light energy or photons with high correlation for the first time.

The achievement, published in Nature Physics, marks a significant milestone in developing quantum technologies. The researchers observed it stimulated light emission, which Einstein predicted in 1916, in single photons for the first time.