Phys.org December 19, 2024 It is crucial to verify quantum protocols before they can be trusted in safety and security-critical applications. Researchers in Japan proposed Basic Dynamic Quantum Logic (BDQL) to formalize and verify sequential models of quantum protocols with a support tool developed in Maude. As BDQL does not support concurrency in its formalization they introduced Concurrent Dynamic Quantum Logic (CDQL) to formalize and verify concurrent models of quantum protocols. They extended the syntax of BDQL to CDQL and made a transformation from CDQL to BDQL without interrupting the semantics of BDQL. They made new support tools in Maude […]
Tag Archives: S&T Japan
A new way of thinking about skyrmion motion could lead to more robust electronics
Phys.org December 19, 2024 When the skyrmion lattice (SkL) acquires a drift velocity under conduction electron flow, an emergent electric field is also generated. The resulting emergent electrodynamics dictate the magnitude of the topological Hall effect (THE) by the relative motion of SkL and conduction electrons. Researchers in Japan reported the emergent electrodynamics induced by SkL motion in Gd2PdSi3, facilitated by its giant THE. They observed the dynamic transition of the SkL motion from the pinned to creep regime and finally to the flow regime, in which the THE was totally suppressed. According to the researchers the Galilean relativity required […]
Spintronics memory innovation: A new perpendicular magnetized film
Phys.org December 27, 2027 FeCo(B) is a current standard magnetic material for perpendicular magnetic tunnel junctions (p-MTJs). A team of researchers in Japan reported PMA in metastable bcc Co-based alloy, i.e. bcc CoMnFe thin films which were known to exhibit large TMR effect when used for electrodes of MTJs with the MgO barrier. Their ab-initio calculation suggested that PMA originates from tetragonal strain and the value exceeds 1 MJ/m3 with optimizing strain and alloys composition. The simulation of the thermal stability factor indicated that the magnetic properties obtained satisfied the requirement of the data retention performance of X-1X nm STT-MRAM. […]
Cooperative motion by atoms protects glass from fracturing
Phys.org December 2, 2024 The slow β, or Johari–Goldstein (JG) relaxation process, has been widely observed in glasses and is known to induce the stress relaxation associated with mechanical properties. So far, jumping motions of only a fraction of the particles were believed to contribute to the JG process in glass. However, there is no direct experimental evidence of the atomic-scale images due to the difficulties in microscopic observation. Researchers in Japan observed atomic motions in the quasi-spherical model ionic-glass-former calcium potassium nitrate. The experiment directly indicated that most particles underwent angstrom-scale motions in the time scale of the JG […]
Breakthrough in clean energy: Scientists pioneer novel heat-to-electricity conversion
Nanowerk November 26, 2024 Materials with axis-dependent conduction polarity (ADCP), which exhibit electron-like and hole-like conduction along distinct crystallographic axes, have garnered interest as potential candidates for effective transverse thermoelectric (TTE) conversion. However, the challenge of designing materials with ADCP is still unresolved. Researchers in Japan conducted experimental and computational investigations on the ADCP in thermopower of WSi single crystals and found that the ADCP stems from the mixed-dimensionality of the Fermi surfaces, characterized by the coexistence of quasi-one-dimensional electron-like and quasi-two-dimensional hole-like sheets. They demonstrated TTE conversion in WSi single crystals by detecting the electromotive force along the perpendicular […]
Cooling with light: Exploring optical cooling in semiconductor quantum dots
Phys.org November 26, 2024 Highly efficient anti-Stokes (AS) photoluminescence (PL) is observed from halide perovskite quantum dots (QDs) due to their strong electron–phonon interactions. However, the PL quantum efficiency in QDs is primarily dominated by multiparticle nonradiative Auger recombination processes under intense photoexcitation, which impose limits on the optical cooling gain. Researchers in Japan investigated the Auger recombination of dot-in-crystal perovskites and quantitatively estimated the maximum optical cooling gain and the corresponding excitation intensity. Their optical cooling experiments demonstrated a maximum photo cooling of approximately 9 K from room temperature confirming that increasing the excitation intensity led to a transition […]
Making a difference: Efficient water harvesting from air possible
Eurekalert November 27, 2024 Liquid moisture adsorbents recover water from the atmosphere and used in applications such as atmospheric water harvesting (AWH) and desiccant air conditioning (DAC), allow for flexible device design as well as lower regeneration temperatures. Desorption performance of liquid adsorbents has been less studied. Previously, researchers in Japan combined oligomeric poly(ethylene glycol) (PEG) and oligomeric poly(propylene glycol) (PPG), resulting in a lowered water desorption temperature and enhanced water desorption efficiency, which was facilitated by a “hydrophilicity-difference-induced water transfer (HWT)” mechanism. Now in their study the researchers investigated PEG-PPG copolymer combinations with PEG for enhancing HWT. The results […]
A pathway towards new quantum devices: Electrically defined quantum dots in zinc oxide
Nanowerk November 26, 2024 Quantum devices such as spin qubits have been extensively investigated in electrostatically confined quantum dots using high-quality semiconductor heterostructures like GaAs and Si. Researchers in Japan demonstrated electrostatically forming the quantum dots in ZnO heterostructures. They uncovered the distinctive signature of the Kondo effect independent of the even-odd electron number parity, which contrasts with the typical behavior of the Kondo effect in GaAs. By analyzing temperature and magnetic field dependences, they found that the absence of the even-odd parity in the Kondo effect was not straightforwardly interpreted by the considerations developed for conventional semiconductors. Based on […]
Scientists develop novel high-fidelity quantum computing gate
Phys.org November 22, 2024 Striving for higher gate fidelity is crucial not only for enhancing existing noisy intermediate-scale quantum devices, but also for unleashing the potential of fault-tolerant quantum computation through quantum error correction. Researchers in Japan proposed theoretical scheme, the double-transmon coupler (DTC), that aims to achieve both suppressed residual interaction and a fast high-fidelity two-qubit gate simultaneously, particularly for highly detuned qubits. The state-of-the-art fabrication techniques and a model-free pulse-optimization process would enable not only efficient fault-tolerant quantum computing with error correction but also effectively mitigate errors in current noisy intermediate-scale quantum devices. According to the researchers the […]
Team creates world’s first tunable-wavelength blue semiconductor laser
Phys.org November 18, 2024 By introducing wavelength tunability, InGaN single longitudinal mode lasers can be used for pumping wavelength conversion devices with a small pump wavelength tolerance. Researchers in Japan designed a 405 nm InGaN tunable slotted laser designed and fabricated by a simple process without high-resolution lithography and epitaxial regrowth leading to continuous-wave single-mode oscillation. By current injection to active and slotted channels separately, they demonstrated a wavelength tuning range of 0.55 nm in InGaN in-plane single-mode lasers… read more. Open Access TECHNICAL ARTICLE