The idea sounds almost like science fiction: two tiny particles that are quantum mechanically linked might also be connected by microscopic shortcuts through spacetime itself, tiny wormholes. This possibility, known as the ER = EPR conjecture, has become a serious topic at the frontier where quantum mechanics meets gravity. The entanglement-is-just-a-wormhole idea The initials point […]
Author: Florian Neukart, Assistant professor of Physics, Leiden University Time feels like the most basic feature of reality. Seconds tick, days pass and everything from planetary motion to human memory seems to unfold along a single, irreversible direction. We are born and we die, in exactly that order. We plan our lives around time, measure […]
Author: Marika Taylor, Pro-vice-chancellor, Professor, University of Birmingham In 1980, Stephen Hawking gave his first lecture as Lucasian Professor at the University of Cambridge. The lecture was called “Is the end in sight for theoretical physics?” Hawking, who later became my PhD supervisor, predicted that a theory of everything – uniting the clashing branches of […]
Einstein Authors: Valerio Faraoni, Professor, Physics & Astronomy, Bishop’s University and Andrea Giusti, Postdoctoral fellow, Swiss Federal Institute of Technology Zurich Einstein’s theory of gravity — general relativity — has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime […]
DIPC Electronic Properties • Quantum physics • Theoretical physics
Density functional theory (DFT) is a theoretical treatment of molecules in which the electron density is considered rather than the wave functions of individual electrons. In other words, it is a way of describing many-electron, in general, many-fermion, systems in which the energy is a funtional of the density of electrons (fermions). DFT is without […]
Symmetries play a fundamental role in Physics, and more specifically in Quantum Physics. It is well known that symmetries lead to degeneracy and to conserved currents in closed quantum systems (meaning that they do not interact with an environment). In the more realistic scenario of Open Quantum Systems (meaning that the quantum system does interact […]
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 […]
No matter what you build or how much care you take building it, it would have defects. It seems it is a rule of nature: every time chaos gives way to order, from matter itself coming into existance in the very early universe to the formation of a crystal in a modern laboratory, defects appear […]
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 […]
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 […]