A model of a physical system that can be solved exactly and the dynamics of which are characterized by regular rather than chaotic motion is called an integrable model. Integrable models can occur in Newtonian mechanics and quantum mechanics, with the harmonic oscillator being an example of such a model in both cases. Integrability has […]
In most physical systems, particles interact locally or at short distances only. Still, l ong-range interactions, like electromagnetic forces, play a crucial role in quantum physics and chemistry. They are a key ingredient for many phenomena, from molecular binding to high-temperature superconductivity. While their exact treatment in quantum many-body systems remains numerically challenging, analog quantum […]
It is very difficult to obtain exact solutions to systems involving interactions between more than two bodies, using either classical mechanics or quantum mechanics. To understand the physics of many-body systems, it is necessary to make use of approximation techniques or model systems that capture the essential physics of the problem. T he complexity of […]
The common understanding of the uncertainty relation says that it is impossible to measure both the position and the momentum of a subatomic particle, in the same instant to unlimited accuracy. The more accurate is the measurement of the momentum, the less accurate is the measurement of the position in that instant, and vice versa […]
When you first study electromagnetism, all the electromagnetic waves you find are plane ones, waves in which the electric and magnetic fields are both orthogonal to the direction of travel of the wave. But this is a mode – the field pattern of the propagating wave – that is somehow ideal, as it exists in […]
Many problems in science and engineering involve understanding how quickly a physical system transitions between distinguishable states and the energetic costs of advancing at a given speed. While theories such as thermodynamics and quantum mechanics put fundamental bounds on the dynamical evolution of physical systems, the form and function of the bounds differ. Rudolf Clausius’s […]