Scanning tunneling microscopy (STM) is a technique in which a fine conducting probe is held close to the surface of a sample. Electrons tunnel between the sample and the probe, producing an electrical signal. The probe is slowly moved across the surface and raised and lowered so as to keep the signal constant. The precision […]
Condensed matter • Materials • Quantum 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 […]
A collection of local magnetic moments arranged in a linear fashion that interact via some spin-spin coupling is generally known as a spin chain . This seemingly simple object is one of the most complex and rich physical systems that have been studied since the advent of quantum mechanics without a decline in interest ever […]
Any physical law in which the magnitude of a physical quantity is proportional to the reciprocal of the square of the distance (1/r 2) 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 […]
A star cluster is a group of stars that are sufficiently close to each other for them to be physically associated. Stars belonging to the cluster are formed together from the same cloud of interstellar gas and have approximately the same age and initial chemical composition. Because of this, and sin the stars in a […]
There is a variety of predictions from the general theory of relativity. And usually they are treated in the popular imagination somehow independently. This would be the case of gravitational waves and gravitational lenses, but in reality nothing prevent them to combine, even at a ‘micro’ level. A gravitational lens is any object that deflects […]
A crystal lattice is formed by a repeated arrangement of atoms, ions, or molecules. Due to the enormous amount of atoms involved it is extremely unlikely that all these will be arranged in perfect order. Some atoms will not be exactly in the right place with the result that the lattice will contain defects. The […]
Originally developed in the context of condensed-matter physics and based on renormalization group ideas, tensor networks have been revived thanks to quantum information theory and the progress in understanding the role of entanglement in quantum many-body systems . Ikerbasque Research Professor Román Orús, one of the world foremost authorities in the field, has just published […]
Quantum simulators—systems that can be engineered and manipulated at will—are useful platforms for verifying model Hamiltonians and understanding more complex or elusive quantum systems. The ability to trap and control particles with the help of well-controlled electromagnetic fields has led to revolutionary advances in the fields of biology, condensed- matter physics, high-precision spectroscopy, and quantum […]
The concept of mean free path is very simple and straightforward: the average distance travelled between collisions by the molecules in a gas, the electrons in a metallic crystal, the neutrons in a moderator, etc. Assuming a couple of things about, for example, how elastic collisions are, it is not difficult to arrive to formulas […]