Phys.org May 9, 2022 A team of researchers in the US (University of Minnesota, UMass Amherst, UC Santa Barbara) has invented a device called catalytic condenser that allowed them to tune the number of electrons at the surface of the catalyst converting one metal to behave like another. They fabricated the catalytic condenser by combining nano-scale film of alumina with graphene, which could be electronically tuned. The condenser uses a combination of nanometer films to move and stabilize electrons at the surface of the catalyst. The power of the device to stabilize electrons is tunable with varying composition of a […]
Hidden distortions trigger promising thermoelectric property
Science Daily May 9, 2022 Conventional structure transitions occur from a low symmetry state to a higher symmetry state upon warming. An international team of researchers (USA – Northwestern University, Brookhaven National Laboratory, Germany) found an unexpected local symmetry breaking in the tetragonal diamondoid compound silver gallium telluride. Upon warming, it evolved continuously from an undistorted ground state to a locally distorted state while retaining average crystallographic symmetry. This is a rare phenomenon previously referred to as emphanisis. The distorted state, caused by the weak orbital hybridization of tetrahedral Ag atoms, resulted in their displacement of the tetrahedron center and […]
It takes three to tangle: Long-range quantum entanglement needs three-way interaction
Science Daily 6, 2022 Researchers in Japan provide simple theorems that show what kinds of long-range entanglement can survive at nonzero temperatures. At temperatures above absolute zero, quantum entanglement must contend with thermal jostling of particles, which is detrimental to long-range entanglement persisting at sufficiently high temperatures. Unlike high-temperature phases, however, there are relatively low temperatures in which not all long-range quantum effects are strictly prohibited, and long-range entanglement can survive even at room temperatures. They proved that entanglement between two subsystems has a finite characteristic length scale at arbitrary temperatures regardless of the system details and the spatial dimension. […]
Laser bursts drive fastest-ever logic gates
Phys.org May 11, 2022 Recently it was experimentally demonstrated that strong non-resonant few-cycle laser pulses can be used to induce phase-controllable currents along gold–silica–gold nanojunctions in the absence of a bias voltage. Since the effect depends on a highly non-equilibrium state of matter, its microscopic origin is unclear and the subject of recent controversy. An international team of researchers (Germany, USA – SLAC National Accelerator Laboratory, University of Rochester, Georgia State University, Los Alamos National Laboratory, Canada) has presented atomistically detailed electronic transport simulations that recover the main experimental observations and offered a simple intuitive picture of the effect. The […]
A New Age of Bioterror: Anticipating Exploitation of Tunable Viral Agents
CTC at West Point APRIL 2022, VOLUME 15, ISSUE 4 According to a team of researchers in the US (Boston College, US Military Academy, West Point, Brooke Army Medical Center) scientists are employing gene editing tools to cure genetic diseases, reduce the effects of climate change, and generate sustainable food sources. These same tools, however, can be used to modify pathogens to develop and deploy novel biological weapons. The nature of these tools and our understanding of specific viral genomes makes this process tunable. Components of a disease such as transmissibility, lethality, and the infectious window can potentially be modified […]
On-chip circuit produces up to six microwave photons at the same time
Phys.org May 10, 2022 An international team of researchers (France, Germany) built a on-chip circuit which is a simple battery-biased superconducting tunnel junction in series with a microwave resonator. At discrete values of the battery voltage, a dc current flows through the circuit, with the emission of several photons at the resonator frequency for each superconducting pair of electrons that tunnels across the junction. They measured the total microwave power emitted and characterized the granularity of the emission both of which were good agreement with a simple theoretical model. In particular, at a small transparency of the tunnel junction, they […]
Optical cavities could provide new technological possibilities
Phys.org May 12, 2022 Coupling between molecules and vacuum photon fields inside an optical cavity has proven to be an effective way to engineer molecular properties, in particular reactivity. An international team of researchers (Norway, Italy) studied optical cavities and how the light trapped in them interacts with atoms, molecules, and other particles. Their framework explained modifications of the electronic structure due to the interaction with the photon field. They showed that the newly developed orbital theory could be used to predict cavity induced modifications of molecular reactivity and pinpoint classes of systems with significant cavity effects. They also investigated […]
Physicists discover light-induced mechanism for controlling ferroelectric polarization
Phys.org May 10, 2022 Ferroelectric materials exhibit ferroelectricity and the ability to polarize spontaneously. Typically, researchers can manipulate and reverse the polarization by the application of an external electric field. Ultrafast interactions between light and matter are another promising route for controlling ferroelectric polarization, but until now researchers have struggled to achieve a light-induced, deterministic control of such polarization. An international team of researchers (USA – University of Arkansas, France, Luxembourg) discovered a so-called “squeezing effect” in ferroelectric materials subject to femtosecond laser pulses. These pulses destroyed the polarization component that is parallel to the field’s direction and created polarization […]
Quantum one-way street in topological insulator nanowires
Phys.org May 12, 2022 Recently quantum mechanical non-reciprocal transport effects that enable a highly controllable rectification were discovered. One such effect is magnetochiral anisotropy (MCA) in which the resistance of a material or a device depends on both the direction of the current flow and an applied magnetic field. However, the size of rectification possible due to MCA is usually extremely small because MCA relies on inversion symmetry breaking that leads to the manifestation of spin–orbit coupling, which is a relativistic effect. To overcome this limitation, an international team of researchers (Switzerland, Germany, Belgium) artificially broke the inversion symmetry via […]
Researchers find a way to form diodes from superconductors
Science Daily May 11, 2022 An international team of researchers (Italy, Spain, USA – MIT) has developed the quasi-particle counterpart, a superconducting tunnel diode with zero conductance in only one direction. The direction-selective propagation of the charge was obtained through the broken electron-hole symmetry induced by the spin selection of the ferromagnetic tunnel barrier: a EuS thin film separating a superconducting Al and a normal metal Cu layer. The Cu/EuS/Al tunnel junction achieved a large rectification (up to ∼40%) already for a small voltage bias (∼200 μV) due to the small energy scale of the system. With the help of an […]