Phys.org September 10, 2021 Researchers in Japan have developed a device consisting of a triple quantum dot on a silicon/silicon–germanium heterostructure and controlled through aluminum gates. Each quantum dot can host one electron, whose spin-up and spin-down states encode a qubit. An on-chip magnet generates a magnetic-field gradient that separates the resonance frequencies of the three qubits, so that they can be individually addressed. They first entangled two of the qubits by implementing a two-qubit gate and then realized three-qubit entanglement by combining the third qubit and the gate. The resulting three-qubit state had a remarkably high state fidelity of […]
Tag Archives: S&T Japan
GaN-on-diamond semiconductor material that can take the heat – 1000 C to be exact
Nanowerk September 9, 2021 Researchers in Japan used the surface activated bonding (SAB) method to successfully bond GaN and diamond and demonstrated that the bonding is stable even when heated to 1,000°C. A 5.3 nm-thick intermediate layer composed of amorphous carbon and diamond is formed at the as-bonded heterointerface. As the team increased annealing temperatures, the layer thickness decreased suggesting the intermediate layer can be completely removed by optimizing the annealing process. As no peeling was observed at the heterointerface after annealing at 1000°C these results indicate that the GaN/diamond heterointerface can withstand harsh fabrications processes. The material shows promise […]
Energy harvesting technology based on ferromagnetic resonance
Phys.org August 24, 2021 Researchers in Japan demonstrated electrical charging using the electromotive force (EMF) generated in a ferromagnetic metal (FM) film under ferromagnetic resonance (FMR). In the case of Ni80Fe20 films, electrical charge due to the EMF generated under FMR can be accumulated in a capacitor; however, the amount of charge is saturated well below the charging limit of the capacitor. In the case of Co50Fe50, electrical charge generated under FMR can be accumulated in a capacitor and the amount of charge increases linearly with the FMR duration time. The difference between the Ni80Fe20 and Co50Fe50 films is due […]
High-rate magnesium rechargeable batteries move one step closer to realization
Science Daily August 23, 2021 Mg/S batteries are some of the most promising rechargeable batteries owing to their high theoretical energy density. However, their development is hindered by low electronic conductivity of S, sluggish Mg2+ diffusion in solid Mg–S compounds formed by discharge, and dissolubility of polysulfides into electrolytes. To address these problems researchers in Japan proposed liquid-S/sulfide composite cathode materials in combination with an ionic liquid electrolyte at intermediate temperatures (∼150 °C). The composite structure is spontaneously fabricated by electrochemically oxidizing metal sulfides, yielding liquid S embedded in a porous metal-sulfide conductive frame. They demonstrated the concept by a […]
Towards next-gen computers: Mimicking brain functions with graphene-diamond junctions
Science Daily August 4, 2021 Researchers in Japan designed graphene-diamond junctions that can mimic the characteristics of biological synapses and key memory functions, opening the doors for next-generation image sensing memory devices. They demonstrated optoelectronically controlled synaptic functions using junctions between vertically aligned graphene (VG) and diamond. The fabricated junctions mimic biological synaptic functions when stimulated with optical pulses and exhibit other basic brain functions such as the transition from short-term memory (STM) to long-term memory (LTM). The VG-diamond arrays underwent redox reactions induced by fluorescent light and blue LEDs under a bias voltage. The researchers attributed this to the […]
Dancing with the light: A new way to make crystals bend by shining light
Nanowerk July 30, 2021 Only very thin crystals (up to 20 microns) can show appreciable mechanical response. Researchers in Japan accidentally discovered that the photothermal effect causes a crystal to bend fast. To create a new, faster bending crystal and clarify the underlying mechanism, they exposed a thin salicylideneaniline derivative crystal to UV light and obtained substantial bending within approximately 1 second. However, the bend angle dropped rapidly with increasing crystal thickness, revealing that the bending was caused by photoisomerization. When they illuminated a thick (>40 microns) crystal with UV light, they observed an extremely rapid bending within several milliseconds, […]
Physicists Have Developed a New Way to Levitate Objects Using Sound Only
Science Alert July 26, 2021 There are significant limitations hindering acoustic tweezers for broad practical application. Although hemispherical arrays of acoustic transducers can be used to create the sound trap, creating just the right sound field to lift an object and move it far from the transducers is very difficult if there is a surface that reflects sound. Researchers in Japan have developed a technique splitting the transducer array into blocks and used an inverse filter to reproduce sounds based on the acoustic waveform. This helps optimize the phase and amplitude of each transducer channel to produce the desired acoustic […]
Preventing oxygen release leads to safer high-energy-density batteries
Phys.org July 13, 2021 Oxide-based cathode materials are key components of secondary batteries. Problems originating from the lattice oxygen instability in oxide-based intercalation cathodes are widely reported, such as capacity degradation, gas generation, and thermal runaway, highlighting the importance of deep insights into the critical factors for lattice oxygen stability. Researchers in Japan Investigated the lattice oxygen stability in layered rock-salt LiNi1/3Co1/3Mn1/3O2−δ with a focus on oxygen release behavior and relevant changes in crystal and electronic structures. Release of lattice oxygen facilitates cation mixing, transition metal slab expansion, and Li slab contraction, thus deteriorating the layered structure. In the beginning […]
Insect-sized robot navigates mazes with the agility of a cheetah
Science Daily July 2, 2021 Researchers in Japan used a curved piezoelectric thin film driven at its structural resonant frequency as the main body of an insect-scale soft robot for its fast translational movements, and two electrostatic footpads were used for its swift rotational motions. These two schemes were simultaneously executed during operations through a simple two-wire connection arrangement. They achieved a high relative centripetal acceleration of 28 body length per square second which is better than those of common insects, including the cockroach. In demonstration the robot passed through a 120-centimeter-long track in a maze within 5.6 seconds. The […]
Stress-free path to stress-free metallic films paves the way for next-gen circuitry
Nanowerk July 4, 2021 To create thin films of tungsten with unprecedentedly low levels of film stress researchers in Japan have been working with scattering (HiPIMS), a sputtering technique. Using argon gas and a tungsten target, the team looked at how ions with different energies arrived at the substrate over time in unprecedented detail. Instead of using a bias pulse set off at the same time as the HiPIMS pulse, they used their knowledge of when different ions arrived and introduced a tiny delay, 60 microseconds, to precisely select for the arrival of high energy metal ions. They found that […]