Anderson Transition.

Quantum mechanics lies at the heart of modern technology. Semiconductors which are fundamental objects in every electronic device depend on quantum mechanical behaviour of electrons and their interaction with lattice structure. One of the interesting phenomena called Anderson transition was reported by Anderson when he found that electrons which should exist as spatially extended states in perfect crystals, eventually localize as the amount of disorder in the crystal increases. Experimentally, however, it has proven very difficult to create the right conditions to observe the transition. Now Julien Chabé and colleagues at the Université des Sciences et Technologies de Lille and the Université Pierre et Marie Curie in Paris have demonstrated an equivalent of the Anderson transition for electrons by trapping cold atoms in a periodic, optical potential. Their experiment, reported in Phys. Rev. Lett. 101, 255702 (2008) – (Published December 15, 2008) overcomes previous difficulties associated with observing the transition in cold atom gasses and also holds the promise of extending the study of the Anderson transition to higher dimensions

Decay of nth excitation in Hormonic Oscillator

Harmonic oscillator is one of the fundamental system that every student of physics is required to work in both classical and quantum worlds. The understanding of this systems helps in resolving many problems eg propagation of sound in air, lattice vibration of crystals, interaction of radiation with matter, shell closures in nuclear system etc. It is perhaps ironic, then, how challenging it is to actually prepare a pure harmonic oscillator state with a well-defined excitation number n. Now, using different methods, two groups—Michel Brune and colleagues at the Laboratoire Kastler Brossel of the CRNS and Collège de France, both in Paris, and Haohua Wang and colleagues at the University of California in Santa Barbara (UCSB)—have created these nonclassical states of the harmonic oscillator and performed a detailed study of how they decay in time. The experiments, reported in Phys. Rev. Lett. 101, 240401 (2008) – Published December 08, 2008, demonstrate that the lifetime of a Fock state with excitation number n scales as 1/n, as predicted by theory

The many shapes of spining drop

This week an interesting article " The many shapes of spinning drops" has been published in PRL. In this research article the author focuses on how different shapes of a liquid drop change with diamagnetic levitation. The results obtained are compared with theoretical predictions. For details download the paper from American physical society link Phys. Rev. Lett. 101, 234501 (2008)

Lets try to understand our universe.

Physics deals with the physical structure of our universe. In a broader sense, our universe is composed of space-time, matter and radiation. These fundamental constituents interact via known four forces. The basic problem of physics from last 100 years has been to unify the known interactions into a single consistent theory “Theory of everything”. The purpose of this Blog is to help my students to keep track of current happenings in physics. To help them to develop physics oriented brains so that they can take this subject seriously and would help in unlocking the mysteries of nature. The Blog is open to all Physics Lovers to paste their comments