Deep slow-slip events promote seismicity in northeastern Japan megathrust

The sliding movement between oceanic and crustal plates in subduction zones is accommodated through both earthquakes and quasi-static or transient aseismic slip. On northeastern Japan megathrust, aseismic transients, known as slow-slip events, are suggested to precede and trigger major earthquakes in their immediate surroundings. However, the geodetic evidence for these episodic slow-slip events, as well as their link to the seismicity on neighboring locked segments of the megathrust, is missing. Here, we combine the on-shore geodetic data set with seismic observations during the interseismic period of 1996–2003 and demonstrate that episodic slow-slip events are prevalent across the down-dip portion (∼30–70 km depth) of the megathrust and the associated stress changes modulate the seismicity rate on the neighboring seismogenic zone. Consequently, small- to moderate-size earthquakes are periodically triggered, whose interaction through a domino effect might occasionally lead to major earthquakes. This observation has a profound impact on the estimation of seismic hazard in the region, introducing a new triggering mechanism that acts across the megathrust to the extent that has not been acknowledged before

Quantum algorithm for collisionless Boltzmann simulation of self-gravitating systems

The collisionless Boltzmann equation (CBE) is a fundamental equation that governs the dynamics of a broad range of astrophysical systems from space plasma to star clusters and galaxies. It is computationally expensive to integrate the CBE directly in a phase space, and thus the applications to realistic astrophysical problems have been limited so far. Recently, Todorova \& Steijl (2020) proposed an efficient quantum algorithm for solving the CBE with a significantly reduced computational complexity. We extend the method to perform quantum simulations that follow the evolution of self-gravitating systems. We first run a 1+1 dimensional test calculation of free streaming motion on 64$\times$64 grids using 13 simulated qubits and validate our method. We then perform simulations of Jeans collapse, and compare the result with analytic and linear theory calculations. We propose a direct method to generate initial conditions as well as a method to retrieve necessary information from a register of multiple qubits. Our simulation scheme achieves $\mathcal{O}(N_v^3)$ less computational complexity than the classical method, where $N_v$ is the number of discrete velocity grids per dimension. It will thus allow us to perform large-scale CBE simulations on future quantum computers.Comment: 10 pages, 9figure

Improvement of zone control induction heating equipment for high-speed processing of semiconductor devices

In order to process a semiconductor device of high quality, uniform heating is necessary, but it is not easy to heat uniformly with conventional induction heating equipment. To solve this problem, zone control induction heating equipment has been jointly developed. In this paper, we examine the effect of dividing an induction heater into several small coil groups having different current and frequency, using the finite-element method. We describe the heating characteristics of the zone control coil groups and show that nearly uniform heating is possible by controlling both current and frequency.</p

Quantum algorithm for the Vlasov simulation of the large-scale structure formation with massive neutrinos

Miyamoto K., Yamazaki S., Uchida F., et al. Quantum algorithm for the Vlasov simulation of the large-scale structure formation with massive neutrinos. Physical Review Research 6, 013200 (2024); https://doi.org/10.1103/PhysRevResearch.6.013200.Investigating the cosmological implication of the fact that neutrino has finite mass is of importance for fundamental physics. In particular, massive neutrino affects the formation of the large-scale structure (LSS) of the universe, and, conversely, observations of the LSS can give constraints on the neutrino mass. Numerical simulations of the LSS formation including massive neutrino along with conventional cold dark matter is thus an important task. For this, calculating the neutrino distribution in the phase space by solving the Vlasov equation is a suitable approach, but it requires solving the PDE in the (6+1)-dimensional space and is thus computationally demanding: Configuring ngr grid points in each coordinate and nt time grid points leads to O(ngr6) memory space and O(ntngr6) queries to the coefficients in the discretized PDE. We propose a quantum algorithm for this task. Linearizing the Vlasov equation by neglecting the relatively weak self-gravity of the neutrino, we perform the Hamiltonian simulation to produce quantum states that encode the phase-space distribution of neutrino. We also propose a way to extract the power spectrum of the neutrino density perturbations as classical data from the quantum state by quantum amplitude estimation with accuracy ϵ and query complexity of order Õ[(ngr+nt)/ϵ]. Our method also reduces the space complexity to O[polylog(ngr/ϵ)] in terms of the qubit number, while using quantum random access memories with O(ngr3) entries. As far as we know, this is the first quantum algorithm for the LSS simulation that outputs the quantity of practical interest with guaranteed accuracy

Influence of order in stepwise electroless deposition on anode properties of thick-film electrodes consisting of Si particles coated with Ni and Cu

Nickel and copper were coated on Si particles by a stepwise electroless deposition technique in which the coating orders of the metals were exchanged. Thick-film electrodes for Li-ion batteries were prepared by a gas-deposition method using the coated Si particles, and the anode performance of these electrodes was investigated. For (Cu, Ni)-coated Si particles obtained by primary Cu deposition and successive Ni deposition, Cu and Ni metal layers were individually deposited on the Si particles. In contrast, in case of (Ni, Cu)-coated Si particles prepared by primary Ni deposition, Cu layer stacked on Ni layer owing to a high catalytic activity of Ni, forming a thicker coated layer. The latter electrode exhibited notably improved performance with the discharge capacities over 1000 mA h g-1 maintained until 400th cycle. The layer stack of Cu on Ni is probably effective for a release of a stress from the Si particles during charge–discharge reactions