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 […]
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 […]
One of the unique features of the chemistry of carbon (and, to some extent, silicon) is its ability to form long chains of atoms. Polymers are substances that have macromolecules composed of many repeating units (known as ‘mers’). Many naturally occurring substances are polymers, including rubber and many substances based on glucose, such as the […]
Condensed matter • DIPC Attosecond Physics • Materials • Physics
In 1882, Heinrich Hertz devoted himself to the study of electromagnetism, including the recent and still generally unappreciated work of Maxwell. Two years later he began his famous series of experiments with electromagnetic waves. During the course of this work, Hertz discovered the photoelectric effect, which has had a profound influence on modern physics. The […]
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 […]
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 Mars 2020 rover mission is the next step in robotic exploration of the Red Planet. Unlike Curiosity, Mars 2020 will try to find answers to key questions about the potential for life on Mars, seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life […]
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 […]
Man does not live by hardware alone. Indeed, great material and conceptual improvements in the machinery of optical microscopes have occurred in recent decades. The examples are numerous (some example here; https://mappingignorance.org/2013/12/23/bessel-beam-plane-illumination-microscopy-another-smart-solution-for-an-old-challenge/). However, what is being achieved only with software and computing power seems a matter of magic. It is not only that programs and […]
Elements with 4f or 5f electrons in unfilled electron bands and their componuds , which have ions carrying magnetic moments but do not magnetically order, or only do so at very low temperatures, are generally known as heavy-fermion or heavy electron systems because the scattering of the conduction electrons with the magnetic ions results in […]