- Quenched disorder
In

statistical physics , a system is said to present**quenched disorder**when some parameters defining its behaviour are random variables which do not evolve with time, i.e.: they are quenched or "frozen". As a typical example, we may cite spin glasses. It is opposite toannealed disorder , where the random variables are allowed to evolve themselves.In mathematical terms, the

**quenched disorder**is harder to analyze than its annealed counterpart, since the thermal and the noise averaging play very different roles. In fact, the problem is so hard that few techniques to approach each are known, most of them relying on approximations. The most used isReplica Theory , a technique based on a mathematical analytical continuation known as thereplica trick which, although giving results in accord with experimentations in a large range of problems, is not generally proven to be a rigorous mathematical procedure. More recently it has been shown by rigorous methods, however, that at least in the archetypical spin-glass model (the so-calledSherrington-Kirkpatrick model ) the replica based solution is indeed exact; this area is still subject of research. The second most used technique in this field isgenerating functional analysis . This method is based on path integrals, and is in principle fully exact, although generally more difficult to apply than the replica procedure.

*Wikimedia Foundation.
2010.*