糖心TV

Ring polymers interpenetrate and “pin” one-another’s motion. To what extent do concentrated solutions, or melts, of ring polymers thread through one another at equilibrium? An analogous system is a well-shaken bucket full of very long rubber bands. If one attempts to withdraw a single rubber band it is very likely that a large tangle of interpenetrating rubber bands will instead emerge. This is to be contrasted with an attempt to withdraw a single strand from a bowl of freshly cooked spagetti, analogous to a system of linear polymers.

The correlation function is an important quantity in the physics of interacting quantum systems such as, e.g. ultracold quantum gases, because it provides information about the quantum many-body wave function beyond a simple density profile. We explicitly calculate the local correlation functions in terms of interaction strength and symmetry phase at zero, low, and intermediate temperatures. We also express the leading order of the short distance non-local correlation functions of the strongly repulsive Bose gas in terms of the wave function of M bosons at zero collision energy and zero total momentum. These general formulas of the higher-order local and non-local correlation functions of the 1D Bose gas provide new insights into the many-body physics.

Citation: EJKP Nandani et al 2016 New J. Phys. 18 055014

Ordered materials such as Bose condensates, and liquid crystals display complex three-dimensional structures. Research by Thomas Machon and Gareth Alexander provides new insights into their behaviour.

Oscillations of solar coronal loops are observed to be strongly damped. This can be explained by mode coupling, which coverts the wave energy from bulk transverse motions to localised, unresolved azimuthal motions. Using the highest quality data currently available, we have found evidence for the Gaussian damping profile predicted by the recently developed theory of damping by mode coupling.