# Category Archives: Quantum physics

## Structurally well-defined boundaries in a fully accessible quantum spin Hall insulator

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 measure a potential difference at right angles to both the current and […]

## Topology of disconnected elementary band representations

The revolutionary theory of topological quantum chemistry , a description of the universal global properties of all possible band structures and materials, diagnoses topological phases based on elementary band representations. A set of bands is topological if it lacks […]

## Surface-Enhanced Molecular Electron Energy Loss Spectroscopy

Chemists have a range of different spectroscopic techniques to study organic molecules. All of these techniques are based on spectra generated by a range of electronic transitions and vibrations, key excitations in matter, the study of which provides information about […]

## HOTI bismuth

The properties of bismuth have long defied classification, placing it in a category of its own. Now, as if it was not enough, it turns out its electronic structure has higher-order topology. This has been shown by an international team […]

## Helium atom scattering can measure electron−phonon interaction properties of surfaces

Atom scattering at low energies has a long history as a useful probe of surface properties. The most common atomic projectiles are helium atoms formed into a monoenergetic beam directed toward the surface with energies in the thermal range, meaning […]

## Beyond the point-dipole approximation

The wave nature of light expresses itself in the propagation all over space, showing an intrinsic limitation to be localized beyond the so-called diffraction limit which is of the order of half the wavelength of the photons propagating. However when […]

## How to extract the interacting spectral function from a ground state DFT calculation

The electronic wave function of an n-electron molecule depends on 3n spatial and n spin coordinates. In a sense, the wave function of a many-electron molecule contains more information than is needed and is lacking in direct physical significance. This […]

## Temperature dependence of rare earth valence has nothing to do with Kondo temperature

The scattering of conduction electrons in metals owing to impurities with magnetic moments is known as the Kondo effect, after Jun Kondo, who analysed the phenomenon in 1964. This scattering increases the electrical resistance and has the consequence that, in […]

## What bounds a molecular solid together?

We usually think of crystals as composed of different atoms in certain proportions, this proportion being the molecular fórmula that represents the crystal. However, it is not surprising that any molecule could be the basis of a crystal structure, whether […]

## Ordinary experience vs. quantum experience

We usually think of nature as existing completely independently of us and possessing a definite reality and behaviour even when we are not observing it. For instance, you assume that the world outside of the place where you are now […]