Quantum critical pointA quantum critical point is a point in the phase diagram of a material where a continuous phase transition takes place at absolute zero. A quantum critical point is typically achieved by a continuous suppression of a nonzero temperature phase transition to zero temperature by the application of a pressure, field, or through doping. Conventional phase transitions occur at nonzero temperature when the growth of random thermal fluctuations leads to a change in the physical state of a system.
SupermultipletIn theoretical physics, a supermultiplet is a representation of a supersymmetry algebra, possibly with extended supersymmetry. Then a superfield is a field on superspace which is valued in such a representation. Naïvely, or when considering flat superspace, a superfield can simply be viewed as a function on superspace. Formally, it is a section of an associated supermultiplet bundle. Phenomenologically, superfields are used to describe particles.
Phonon polaritonsPhonon polaritons are a type of quasiparticle that can form in a diatomic ionic crystal due to coupling of transverse optical phonons and photons. They are particular type of polariton, which behave like bosons. Phonon polaritons occur in the region where the wavelength and energy of phonons and photons are similar, as to adhere to the avoided crossing principle. Phonon polariton spectra have traditionally been studied using Raman spectroscopy.
Magnetic tweezersMagnetic tweezers (MT) are scientific instruments for the manipulation and characterization of biomolecules or polymers. These apparatus exert forces and torques to individual molecules or groups of molecules. It can be used to measure the tensile strength or the force generated by molecules. Most commonly magnetic tweezers are used to study mechanical properties of biological macromolecules like DNA or proteins in single-molecule experiments. Other applications are the rheology of soft matter, and studies of force-regulated processes in living cells.
Kohn anomalyIn the field of physics concerning condensed matter, a Kohn anomaly (also called the Kohn effect) is an anomaly in the dispersion relation of a phonon branch in a metal. It is named for Walter Kohn. For a specific wavevector, the frequency (and thus the energy) of the associated phonon is considerably lowered, and there is a discontinuity in its derivative. They have been first proposed by Walter Kohn in 1959. In extreme cases (that can happen in low-dimensional materials), the energy of this phonon is zero, meaning that a static distortion of the lattice appears.
Order and disorderIn physics, the terms order and disorder designate the presence or absence of some symmetry or correlation in a many-particle system. In condensed matter physics, systems typically are ordered at low temperatures; upon heating, they undergo one or several phase transitions into less ordered states. Examples for such an order-disorder transition are: the melting of ice: solid-liquid transition, loss of crystalline order; the demagnetization of iron by heating above the Curie temperature: ferromagnetic-paramagnetic transition, loss of magnetic order.
ChargeonLes chargeons, ou holons, sont l'une des trois quasi-particules, avec les spinons et les orbitons, qui résultent de la division des électrons contenus dans les solides au cours du processus de séparation spin-charge, se produisant lorsqu'ils sont extrêmement confinés et à des températures proches du zéro absolu. L'électron peut toujours être théoriquement considéré comme un état lié des trois quasi-particules, avec le spinon portant le spin de l'électron, l'orbiton caractérisant l'orbitale atomique et le chargeon portant la charge électrique, mais dans certaines conditions ils peuvent se déconfiner et se comporter comme des particules indépendantes.
SpinonLes spinons sont l'une des trois quasi-particules, avec les chargeons et les orbitons, qui résultent de la division des électrons contenus dans les solides au cours du processus de séparation spin-charge, se produisant lorsqu'ils sont extrêmement confinés et à des températures proches du zéro absolu. L'électron peut toujours être théoriquement considéré comme un état lié des trois quasi-particules, avec le spinon portant le spin de l'électron, l'orbiton caractérisant l'orbitale atomique et le chargeon portant la charge électrique, mais dans certaines conditions ils peuvent se comporter comme des particules indépendantes.
Ultracold atomIn condensed matter physics, an ultracold atom is an atom with a temperature near absolute zero. At such temperatures, an atom's quantum-mechanical properties become important. To reach such low temperatures, a combination of several techniques typically has to be used. First, atoms are trapped and pre-cooled via laser cooling in a magneto-optical trap. To reach the lowest possible temperature, further cooling is performed using evaporative cooling in a magnetic or optical trap.
Pince optiqueLa pince optique est un outil optique introduit en 1987 et utilisé en laboratoire qui permet le piégeage et la manipulation de cibles telles que les cellules, organites ou particules. Elle utilise la force résultant de la réfraction d’un faisceau laser en milieu transparent, pour maintenir et déplacer physiquement des objets diélectriques microscopiques. Des pinces optiques multiples peuvent même être utilisées pour manipuler simultanément plusieurs cibles.
