One of the most mysterious features of quantum mechanics is that if two particles (or photons) interact at some point in time then the properties of these particles will remain connected at future times. A consequence of this is that determining the quantum state of one of the particles simultaneously determines the quantum state of […]
Condensed matter • Materials • Nanotechnology • Quantum physics • Theoretical physics
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 […]
We all know what glass is, don’t we? We just point to the nearest window and it is that transparent sheet. Humans have been producing glass for at least 6,000 years, way before they knew how to smelt iron. Actually, the chemistry is well known: to produce window glass we just heat a mixture of […]
Graphene nanoribbons (GNRs), are strips of graphene with ultra-thin width (<50 nm). Graphene ribbons, introduced as a theoretical model by Mitsutaka Fujita and coauthors to examine the edge and nanoscale size effect in graphene, have emerged as a promising material for nanoelectronics, as they combine many of the extraordinary properties of graphene with a high […]
In the quantum theory of many-body systems, collective oscillations are called collective excitations. In a quantum context, everything is quantized. Hence, collective excitations become quantized modes because of the cooperative motion of the whole system as a result of interactions between particles. They may be electronic excitations in atoms and are referred excitons. In most […]
Superconductivity is a physical phenomenon in which some materials exhibit zero electrical resistance when cooled down below a certain critical temperature. As surprising as it can be, the critical temperature of these materials can be modified by reducing the sample size to about a million times the size of the objects we are used to […]
Chemistry • Condensed matter • Materials • Nanotechnology • Quantum physics
Usually, optical activity is understood as the ability some substances have to change the handedness of polarized light when it goes through them. Molecules that show optical activity have no plane of symmetry. The commonest case of this is in organic compounds in which a carbon atom is linked to four different groups. An atom […]
A quantum dot (QD) is a nanometric crystalline structure of semiconductor materials. In a QD electrons are confined in a region of space, thus creating a well defined structure of energy levels that depends very much on the size and shape of the quantum dot. This structure resembles that of atoms, that is why sometimes […]
There are chemical compounds, called isomers, that have the same molecular formulae but different molecular structures or different arrangements of atoms in space. In constitutional isomerism the molecules have different molecular structures: i.e., they may be different types of compound, or they may simply differ in the position of the functional group in the molecule […]
Condensed matter • Materials • Physics • Theoretical physics
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 […]
