Category archives: Theoretical physics

Magnetic fields and quantum symmetries, two old (and new) friends

Magnetic fields and quantum symmetries, two old (and new) friends

Quantum physicsTheoretical physics

By Instituto Carlos I

Symmetries play a fundamental role in Physics, and more specifically in Quantum Physics. It is well known that symmetries lead to degeneracy and to conserved currents in closed quantum systems (meaning that they do not interact with an environment). In the more realistic scenario of Open Quantum Systems (meaning that the quantum system does interact […]

Universal speed limits in thermodynamics away from equilibrium

Universal speed limits in thermodynamics away from equilibrium

DIPC Quantum SystemsPhysicsTheoretical physics

By DIPC

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 […]

Second-harmonic generation in a quantum emitter – metallic nanoparticle hybrid

Second-harmonic generation in a quantum emitter – metallic nanoparticle hybrid

Condensed matterMaterialsNanotechnologyQuantum physicsTheoretical physics

By DIPC

When two photons with the same energy interact with a nonlinear material, they “combine” and generate a new photon with twice the energy of the initial photons. More precisely, two photons at the fundamental frequency are absorbed by a plasmonic structure to emit one photon at the second-harmonic frequency. This is called second-harmonic generation. Second-harmonic […]

An additional contribution to the spin Hall effect induced by an electric current

An additional contribution to the spin Hall effect induced by an electric current

Condensed matterMaterialsPhysicsTheoretical physics

By DIPC

The interactions between moving charges and magnetic fields can be quite complicated; more if we consider the quantum effects. One example is the collection of Hall effects. Imagine that we have a conductor or a semiconductor through which a current is flowing. Then we apply a strong transverse magnetic field. As a result, we can […]

A local quantum emitter can be used to sense the environment of a molecule with the minimal quantum of energy

A local quantum emitter can be used to sense the environment of a molecule with the minimal quantum of energy

Condensed matterMaterialsNanotechnologyQuantum physicsTheoretical physics

By DIPC

Plasmonic nanostructures confine light to dimensions far smaller than the free-space wavelength, as they mix optical fields with electronic excitations. It was not until the 1990s, with the appearance of accurate and reliable nanofabrication techniques, that plasmonics blossomed. It was found then that local fields around nanostructures could be directly measured by near-field scanning optical […]

A theory of spin hall magnetoresistance to study magnetism at interfaces

A theory of spin hall magnetoresistance to study magnetism at interfaces

Condensed matterMaterialsQuantum physicsTheoretical physics

By DIPC

The interactions between moving charges and magnetic fields can be quite complicated; more if we consider the quantum effects. One example is the collection of Hall effects. Imagine that we have a conductor or a semiconductor through which a current is flowing. Then we apply a strong transverse magnetic field. As a result, we can […]

Inverse-square law interaction at the nanoscale

Inverse-square law interaction at the nanoscale

Condensed matterQuantum physicsTheoretical physics

By DIPC

Any physical law in which the magnitude of a physical quantity is proportional to the reciprocal of the square of the distance (1/r2) from the source of that property is known as an inverse-square law. Newton’s law of gravitation and Coulomb’s law are both examples. When Newton proposed his law of gravitation in his Philosophiæ […]

The road to quantum gravity (4): The flow of time for massive objects

The road to quantum gravity (4): The flow of time for massive objects

CosmologyHistoryTheoretical physics

By Daniel Fernández

We started this series discussing the basic ingredients of the Universe: events, spacetime, causality. In the last chapter, we introduced massive objects (and thus, matter), which appear as a generalization of the so-called photon box. As it moves, any object traces a path. Physicists call it worldline. We established that a massive object never moves […]