Science Daily February 7, 2023 Recent explorations pairing a sodium anode and aluminum cathode have demonstrated reversible, energy dense Na-Al cells with excellent rate capability using the electrochemical reaction between a molten Na anode and a NaAlCl4/Al cathode. A team of researchers in the US (Pacific Northwest National Laboratory, industry) investigated the fundamental aspects of the NaAlCl4-NaAl2Cl7 reaction chemistry, and Na-metal/chloroaluminate batteries with excellent reversibility and areal capacity. Increasing the voltage window of the chloroaluminate Na-Al battery higher voltage was contributed by the acidic chloroaluminate cathode reaction, unlocking an additional specific energy of ∼119 Wh kg−1 by utilizing the conversion […]
Researchers devise a new path toward ‘quantum light’
Science Daily February 2, 2023 Strongly driven systems of emitters offer an attractive source of light over broad spectral ranges up to the X-ray region. A key limitation of these systems is that the light they emit is mostly classical. An international team of researchers (USA – Harvard University, MIT, UK, Israel, Austria) overcame this constraint by building a quantum-optical theory of strongly driven many-body systems, showing that the presence of correlations among the emitters creates emission of non-classical many-photon states of light. They considered the example of high-harmonic generation, by which a strongly driven system emits photons at integer […]
A quasiparticle that can transfer heat under electrical control
Science Daily February 1, 2023 An international team of researchers (USA – Ohio State University, Japan) has experimentally shown that an external electric field affects the velocity of the longitudinal acoustic phonons (vLA), thermal conductivity (κ), and diffusivity (D) in a bulk lead zirconium titanate–based ferroelectric. They found that phonon conduction dominates κ due to changes in the phonon dispersion, not in the phonon scattering. Since the ferron carries heat, that makes the amount of heat carried dependent on the electrical field. They wrote a new theory that relates an external electric field, the strain it induces in a ferroelectric, […]
Scientists open new window on the physics of glass formation
Phys.org January 24, 2023 A common feature of glasses is the “boson peak”, observed as an excess in the heat capacity over the crystal or as an additional peak in the terahertz vibrational spectrum. The microscopic origins of this peak are not well understood; the emergence of locally ordered structures has been put forward as a possible candidate. An international team of researchers (UK, Slovenia, Japan) has shown that depolarised Raman scattering in liquids consisting of highly symmetric molecules can be used to isolate the boson peak, allowing its detailed observation from the liquid into the glass. The boson peak […]
Scientists realize faster method for quantum key distribution
Phys.org February 8, 2023 In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication parties. Despite their advantageous performance over long communication distances, the requirement of phase locking between two remote lasers is technically challenging. By adopting the recently proposed mode-pairing idea, researchers in China have demonstrated high-performance quantum key distribution without […]
Space dust as Earth’s sun shield
Phys.org February 8, 2023 A team of researchers in the US (University of Utah, Smithsonian Astrophysical Observatory) explored the potential of using dust to shield sunlight. They analyzed different properties of dust particles, quantities of dust and the orbits that would be best suited for shading Earth. They found launching dust from Earth to a way station at the “Lagrange Point” between Earth and the sun (L1) would be most effective. To achieve sunlight attenuation of 1.8%, equivalent to about 6 days per year of an obscured Sun, the mass of dust in the scenarios they considered must exceed 1010 […]
Toward practical quantum optics: Multiphoton qubits from LNOI
Phys.org February 8, 2023 The large-photon-number quantum state is a fundamental but nonresolved request for practical quantum information applications. Researchers in China have proposed a N-photon state generation scheme that is feasible and scalable using lithium niobate on insulator circuits. The scheme was based on the integration of a common building block photon-number doubling unit (PDU) for deterministic single-photon parametric downconversion and upconversion. The PDU relies on a 107-optical-quality-factor resonator and mW-level on-chip power, which is within the current fabrication and experimental limits. N-photon state generation schemes, with cluster and Greenberger–Horne–Zeilinger state as examples, are shown for different quantum tasks… read more. […]
Tropical storms signaled by atmospheric waves, study finds
Phys.org February 7, 2023 Understanding and prediction of tropical cyclone (TC) activity on the medium range remains challenging. Researchers in the UK found that the pre-existing westward-moving equatorial waves can inform the risk of TC occurrence and intensification, based on a dataset obtained by synchronising objectively identified TCs and equatorial waves in a climate reanalysis. Globally, westward-moving equatorial waves can be precursors to 60–70% of pre-tropical cyclogenesis events, and to >80% of the events with the strongest vorticity, related to the favourable environmental conditions within the pouch of equatorial waves. They also found that when storms are in-phase with westward-moving […]
Top Science and Technology Articles for the week of February 3, 2023
Creating ‘ghostly mirrors’ for high-power lasers DARPA Team Begins Work on Field Deployable Whole Blood Equivalent An illuminated water droplet creates an ‘optical atom’ Lightning Strikes Create a Strange Form of Crystal Rarely Seen in Nature MIT engineers grow “perfect” atom-thin materials on industrial silicon wafers New analog quantum computers to solve previously unsolvable problems Physicists observe rare resonance in molecules for the first time Qubits on strong stimulants Recreating the natural light-harvesting nanorings in photosynthetic bacteria Topological acoustic waveguide to help reduce unwanted energy consumption in electronics And others Seawater split to produce ‘green’ hydrogenSolid material that ‘upconverts’ visible light […]
Qubits on strong stimulants
Science Daily January 27, 2023 Optically active semiconductor quantum dots have unparalleled photonic properties, but also modest spin coherence limited by their resident nuclei. The nuclear inhomogeneity has thus far bound all dynamical decoupling measurements to a few microseconds. An international team of researchers (UK, Austria) eliminated the inhomogeneity using lattice-matched GaAs–AlGaAs quantum dot devices and demonstrated dynamical decoupling of the electron spin qubit beyond 0.113(3) ms. Leveraging the 99.30(5)% visibility of our optical π-pulse gates, we use up to Nπ = 81 decoupling pulses and find a coherence times hundreds of microseconds. This scaling manifests an ideal refocusing of strong interactions between the electron and the […]