Phys.org April 3, 2023 Dust is an attractive evidence source, as it accumulates on undisturbed surfaces, often is overlooked by perpetrators, and contains sufficient human DNA for analysis. To assess whether single nucleotide polymorphisms (SNPs) genotyped from indoor dust using massively parallel sequencing could be used to detect known household occupants, a team of researchers in the US (North Carolina State University, MIT Lincoln Laboratory) recruited 13 households and provided buccal samples from each occupant and dust from five predefined indoor locations. They used a software developed to permit mixture analysis and identity searching to assess whether known occupants could […]
Can a solid be a superfluid? Engineering a novel supersolid state from layered 2D materials
Nanowerk March 30, 2023 A supersolid a counterintuitive quantum state in which a rigid lattice of particles flows without resistance, has not been unambiguously realized. An international team of researchers (Belgium, Italy, Australia, Brazil) has revealed a supersolid ground state of excitons in a double-layer semiconductor heterostructure over a wide range of layer separations outside the focus of recent experiments. It conforms to the original Chester supersolid with one exciton per supersolid site, as distinct from the alternative version reported in cold-atom systems of a periodic density modulation or clustering of the superfluid. They provided the phase diagram augmented by […]
Connecting distant silicon qubits for scaling up quantum computers
Phys.org March 31, 2023 Among the many qubit platforms, spin qubits in silicon quantum dots are promising for large-scale integration along with their nanofabrication capability. However, linking distant silicon quantum processors is challenging as two-qubit gates in spin qubits typically utilize short-range exchange coupling, which is only effective between nearest-neighbor quantum dots. Coherent shuttling of a spin qubit enables efficient switching of the exchange coupling with an on/off ratio exceeding 1000, while preserving the spin coherence by 99.6% for the single shuttling between neighboring dots. An international team of researchers (Japan, the Netherlands) has demonstrated a two-qubit controlled-phase gate with […]
Imaging technique reveals electronic charges with single-atom resolution
Phys.org March 31, 2023 A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. An international team of researchers (USA – Harvard University, University of Illinois, University of Maryland, Stanford University, UK) visualized the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope. They discovered nanometer-scale puddles of metallic conduction electrons centered around uranium-site substitutions in the heavy-fermion compound uranium ruthenium silicide (URu2Si2) and around samarium-site defects in the topological Kondo insulator samarium hexaboride (SmB6). These defects disturbed the […]
Major storage capacity in water-based batteries
Science Daily April 4, 2023 Redox-active non-conjugated radical polymers are promising candidates for metal-free aqueous batteries because of the polymers’ high discharge voltage and fast redox kinetics. However, little is known regarding the energy storage mechanism of these polymers in an aqueous environment. The reaction itself is complex and difficult to resolve because of the simultaneous transfer of electrons, ions and water molecules. Researchers at Texas A&M University have demonstrated the nature of the redox reaction for poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) by examining aqueous electrolytes of varying chao-/kosmotropic character using electrochemical quartz crystal microbalance with dissipation monitoring at a range of timescales. […]
A method for designing neural networks optimally suited for certain tasks
MIT News March 30, 2023 While neural networks are used for classification tasks across domains, a long-standing open problem in machine learning is determining whether neural networks trained using standard procedures are consistent for classification, i.e., whether such models minimize the probability of misclassification for arbitrary data distributions. A team of researchers in the US (MIT, UC San Diego) identified, constructed and analyzed infinitely wide networks that were also infinitely deep. Using the recent connection between infinitely wide neural networks and neural tangent kernels, they provided explicit activation functions that could be used to construct networks that achieve consistency. They […]
The modulation of a single-molecule electron source using light
Phys.org March 31, 2023 Applying strong DC electric fields on the apex of a sharp metallic tip causes electrons to be emitted radially from the apex to vacuum magnifying the nanoscopic information on the apex, which serves as a field emission microscope (FEM). When depositing molecules on such a tip, peculiar electron emission patterns such as clover leaves appear. However, the source of these emission patterns has not yet been identified owing to the limited experimental information about molecular configurations on a tip. An international team of researchers (Japan, Germany, France) used fullerene molecules and characterized the molecule-covered tip by […]
Nanophysics: The right twist
Science Daily March 28, 2023 Moiré effects in vertical stacks of two-dimensional crystals give rise to new quantum materials with rich transport and optical phenomena that originate from modulations of atomic registries within moiré supercells. Due to finite elasticity, however, the superlattices can transform from moiré-type to periodically reconstructed patterns. An international team of researchers (Germany, Russia, Austria, Japan) expanded the notion of such nanoscale lattice reconstruction to the mesoscopic scale of laterally extended samples and demonstrated rich consequences in optical studies of excitons in MoSe2–WSe2 heterostructures with parallel and antiparallel alignments. According to the researchers their results provide a […]
Researchers develop novel nonwovens that are electrically conductive but thermally insulating
Phys.org April 4, 2023 Materials with an extremely low thermal and high electrical conductivity that are easy to process, foldable, and nonflammable are required for sustainable applications, notably in energy converters, miniaturized electronics, and high-temperature fuel cells. Given the inherent correlation between high thermal and high electrical conductivity, innovative design concepts that decouple phonon and electron transport are necessary. Researchers in Germany achieved a unique combination of thermal conductivity and electrical conductivity in electrospun nonwovens comprising carbon as the matrix and silicon-based ceramics as nano-sized inclusions with a sea-island nanostructure. The carbon phase modulates electronic transport for high electrical conductivity, […]
Revolutionary battery technology to boost EV range 10-fold or more
Science Daily March 29, 2023 High-capacity anode materials are promising candidates for increasing the energy density of lithium (Li)-ion batteries due to their high theoretical capacities. However, a rapid capacity fading due to the huge volume changes during charge-discharge cycles limits practical applications. Researchers in South Korea developed a layering-charged polymeric binder that could effectively integrate high-capacity anodes using a strong yet reversible Coulomb interaction and enriched hydrogen bonding. The charged polymeric binder built a dynamically charge-directed network on the active materials with high versatility and efficiently dissipated the electrode stress with mechanical properties. In addition, poly(ethylene glycol) (PEG) moieties […]