Lifeboat Foundation

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices.

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a technological revolution by leveraging this newfound knowledge in engineering applications. Spintronics is an emerging field that aims to surpass the limits of traditional electronics by using the spin of electrons, which can be roughly seen as their angular rotation, as a means to transmit information.

But the design of devices that can operate using spin is extremely challenging and requires the use of new materials in exotic states–even some that scientists do not fully understand and have not experimentally observed yet. In a recent study published in Nature Communications, scientists from the Department of Applied Physics at Tokyo University of Science, Japan, describe a newly synthesized compound with the formula KCu₆AlBiO₄(SO₄)₅Cl that may be key in understanding the elusive “quantum spin liquid (QSL)” state. Lead scientist Dr Masayoshi Fujihala explains his motivation: “Observation of a QSL state is one of the most important goals in condensed-matter physics as well as the development of new spintronic devices. However, the QSL state in two-dimensional (2D) systems has not been clearly observed in real materials owing to the presence of disorder or deviations from ideal models.”

A central challenge in developing quantum computers and long-range quantum networks is the distribution of entanglement across many individually controllable qubits¹. Colour centres in diamond have emerged as leading solid-state ‘artificial atom’ qubits^2,3 because they enable on-demand remote entanglement⁴, coherent control of over ten ancillae qubits with minute-long coherence times⁵ and memory-enhanced quantum communication⁶. A critical next step is to integrate large numbers of artificial atoms with photonic architectures to enable large-scale quantum information processing systems. So far, these efforts have been stymied by qubit inhomogeneities, low device yield and complex device requirements. Here we introduce a process for the high-yield heterogeneous integration of ‘quantum microchiplets’—diamond waveguide arrays containing highly coherent colour centres—on a photonic integrated circuit (PIC). We use this process to realize a 128-channel, defect-free array of germanium-vacancy and silicon-vacancy colour centres in an aluminium nitride PIC. Photoluminescence spectroscopy reveals long-term, stable and narrow average optical linewidths of 54 megahertz (146 megahertz) for germanium-vacancy (silicon-vacancy) emitters, close to the lifetime-limited linewidth of 32 megahertz (93 megahertz). We show that inhomogeneities of individual colour centre optical transitions can be compensated in situ by integrated tuning over 50 gigahertz without linewidth degradation. The ability to assemble large numbers of nearly indistinguishable and tunable artificial atoms into phase-stable PICs marks a key step towards multiplexed quantum repeaters^7,8 and general-purpose quantum processors^9,10,11,12.

The goal of ‘femtochemistry’ is to film and control chemical reactions with short flashes of light. Using consecutive laser pulses, atomic bonds can be excited precisely and broken as desired. So far, this has been demonstrated for selected molecules. Researchers at the University of Göttingen and the Max Planck Institute for Biophysical Chemistry have now succeeded in transferring this principle to a solid, controlling its crystal structure on the surface. The results have been published in the journal Nature.

The team, led by Jan Gerrit Horstmann and Professor Claus Ropers, evaporated an extremely thin layer of indium onto a silicon crystal and then cooled the crystal down to −220 degrees Celsius. While the indium atoms form conductive metal chains on the surface at room temperature, they spontaneously rearrange themselves into electrically insulating hexagons at such low temperatures. This process is known as the transition between two phases—the metallic and the insulating—and can be switched by laser pulses. In their experiments, the researchers then illuminated the cold surface with two short laser pulses and immediately afterwards observed the arrangement of the indium atoms using an electron beam. They found that the rhythm of the laser pulses has a considerable influence on how efficiently the surface can be switched to the metallic state.

This effect can be explained by oscillations of the atoms on the surface, as first author Jan Gerrit Horstmann explains: “In order to get from one state to the other, the atoms have to move in different directions and in doing so overcome a sort of hill, similar to a roller coaster ride. A single laser pulse is not enough for this, however, and the atoms merely swing back and forth. But like a rocking motion, a second pulse at the right time can give just enough energy to the system to make the transition possible.” In their experiments the physicists observed several oscillations of the atoms, which influence the conversion in very different ways.

Liquid membranes flip the script on filtration.

Researchers at CRANN and Trinity’s School of Physics have created an innovative new device that will emit single particles of light, or photons, from quantum dots that are the key to practical quantum computers, quantum communications, and other quantum devices.

The team has made a significant improvement on previous designs in photonic systems via their device, which allows for controllable, directional emission of single photons and which produces entangled states of pairs of quantum dots.

Researchers from the Facility for Rare Isotope Beams (FRIB) Laboratory at Michigan State University (MSU) have taken a major step toward a theoretical first-principles description of neutrinoless double-beta decay. Observing this yet-unconfirmed rare nuclear process would have important implications for particle physics and cosmology. Theoretical simulations are essential to planning and evaluating proposed experiments. The research team presented their results in an article recently published in Physical Review Letters.

FRIB theorists Jiangming Yao, research associate and the lead author of the study, Roland Wirth, research associate, and Heiko Hergert, assistant professor, are members of a topical collaboration on fundamental symmetries and neutrinoless double-beta decay. The U.S. Department of Energy Office of Science Office of Nuclear Physics is funding the topical collaboration. The theorists joined forces with fellow topical collaboration members from the University of North Carolina-Chapel Hill and external collaborators from the Universidad Autonoma de Madrid, Spain. Their work marks an important milestone toward a theoretical calculation of neutrinoless double-beta decay rates with fully controlled and quantified uncertainties.

The authors developed the In-Medium Generator-Coordinate Method (IM-GCM). It is a novel approach for modeling the interactions between nucleons that is capable of describing the complex structure of the candidate nuclei for this decay. The first application of IM-GCM to the computation of the neutrinoless double beta decay rate for the nucleus of calcium-48 sets the stage for explorations of the other candidates with controllable theoretical uncertainty.

An international team led by physicists from the Ludwig-Maximilians Universitaet (LMU) in Munich realized a novel genuine time-dependent topological system with ultracold atoms in periodically-driven optical honeycomb lattices.

Topological phases of matter have attracted a lot of interest due to their unique electronic properties that often result in exotic surface or boundary modes, whose existence is rooted in the non-trivial topological properties of the underlying system. In particular, the robustness of these properties makes them interesting for applications.

Periodic driving has emerged as an important technique to emulate the physics of undriven topological solid-state systems. The properties of driven topological systems, however, transcend those of their static counterparts. Using a BEC of 39K loaded into a periodically-modulated optical honeycomb lattice, we could generate such a time-dependent topological system.

Every second, a star dies in the universe. But these stellar beings don’t just completely vanish, stars always leave something behind.

Some stars explode in a supernova, turning into a black hole or a neutron star, while the majority of stars become white dwarfs, a core of the star it once used to be. However, a new study reveals that these white dwarfs contribute more to life in the cosmos than previously believed.

New observations of white dwarf stars reveal their stellar contribution to carbon atoms in the cosmos, one of the building blocks of life.

Samsung’s latest scientific breakthrough might change the very way we perceive semiconductors, largely on account of the fact it’s two-dimensional. Called amorphous boron nitride (a-BN), the substance in question is composed of but a single layer of atoms and characterized by an amorphous (liquid-like) molecule structure. It’s also the best 2D material for insulation ever synthetized, with Samsung hoping it will be able to utilize in production of revolutionary graphene wafers with unprecedentedly low level of electrical interference.

The discovery of a-BN is hardly Samsung’s first foray into 2D materials. The first and possibly most famous such substance — graphene — has been the subject of countless projects at the Korean conglomerate ever since it was first isolated in 2004. Following the 2016 Galaxy Note 7 fiasco, Samsung is believed to have doubled down on graphene R&D with the goal of eventually integrating the 2D material into its batteries, making them more stable, i.e. less prone to spontaneous combustions.

Making graphene batteries is no small feat, however, and it’s been a while since Samsung last made significant inroads on that front. Scalability remains a key issue, particularly in regards to mass-production costs. Graphene wafers, on the other hand, are expected to play a major role in the development and volume production of next-generation server memory modules, as well as DRAM and NAND memory chips.