JPS Hot Topics

Simulating Strongly Coupled Quantum Field Theory with Quantum Algorithms

Nonperturbative quantum field theory problems can often be difficult to solve with classical algorithms. Researchers now develop quantum computing algorithms to understand such problems in the Hamiltonian formalism.

Theoretical Particle Physics

Understanding Relaxor Ferroelectrics with Simple Landau Theory

Third-order nonlinear dielectric susceptibility is measured in the paraelectric phase of Pb(Sc_1/2Ta_1/2)O₃. The linear and nonlinear dielectric susceptibility results can be consistently explained based on the Landau-type free-energy density.

Dielectric, optical, and other properties in condensed matter

Structure and mechanical and thermal properties in condensed matter

Cross-disciplinary physics and related areas of science and technology

Getting Around the Sign Problem to Solve an Open Quantum System

Researchers from Japan have found a novel non-equilibrium quantum system that doesn’t have the sign problem. The transport properties of the system are simulated with a Monte Carlo approach.

Elementary particles, fields, and strings

Theoretical Particle Physics

Quantum Anomaly in a Dirac Fermion System with Spacetime Dependent Mass

Scientists investigate quantum anomalies in a system of Dirac fermions with spacetime dependent mass and show that the anomaly formulas can be expressed in terms of superconnections.

Theoretical Particle Physics

Elementary particles, fields, and strings

Spin Transport in a Two-Dimensional Tilted Dirac Electron System

We propose that spin current in an organic conductor, α-(BETS)₂I₃, is an appropriate physical quantity to detect the topological nature of the material whose electrons obey a quasi-two-dimensional Dirac equation.

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Violation of Fluctuation-Dissipation Theorem Results in Robustness of Fluctuation Against Localization

We study equilibrium current fluctuations in systems without time-reversal symmetry, violating the fluctuation-dissipation theorem. Notably, the off-diagonal fluctuation is insensitive to system imperfections in contrast to other fluctuations and conductivity.

Statistical physics and thermodynamics

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Four-Dimensional XY Quantum Phase Transition in Superfluid Helium-4

Liquid helium confined in nanopores exhibits a quantum superfluid transition at absolute zero. Investigations have revealed that the quantum nature also dominates the finite-temperature superfluid transition, obeying a simple mean-field theory.

Structure and mechanical and thermal properties in condensed matter

Topological Aspects of a Nonlinear System: The Dimerized Toda Lattice

A nonlinear topological phase is shown to emerge in the dimerized Toda lattice. It is experimentally detectable by measuring the voltage propagation in electric circuits.

Electronic structure and electrical properties of surfaces and nanostructures

Electronic transport in condensed matter

Unusual Nonlinear Conductivity in Charge-Ordered α-(BEDT-TTF)₂I₃

Unusual nonlinear conduction is detected in organic molecular salt α-(BEDT-TTF)₂I₃. The observed third-order nonlinear conductivity implies a quadrupole instability hidden in this charge-ordered organic salt.

Electronic transport in condensed matter

Economic Irreversibility: The Universal Guiding Principle of Infection Control

It is preferable to avoid lockdowns, as lockdowns at seriously spread phases are very expensive. It would be economically better to utilize less intense countermeasures as early as possible to avoid lockdowns in later phases.

Statistical physics and thermodynamics

Cross-disciplinary physics and related areas of science and technology