Powered By Blogger

Sunday, April 28, 2013

The strangeness of quantum world: The quantum Zeno effect

The Heisenberg’s uncertainty principle states that separation of the observer from the phenomenon to be observed is not possible because the act of seeing (observing) and comprehending are inherent part of physical phenomenon. This is a direct result of the fact that the position of a particle (x) and its momentum (p) can not be determined precisely. The standard deviation of x distribution multiplied by the standard deviation of p can never be smaller than half of Plank’s constant. The quantum state is a fundamental physical quantity and the act of observation and its entanglement with its environment causes uncertainty. In other words, the observer of a quantum system can influence what he observes.

The quantum Zeno effect describes a situation in which an unstable particle, if observed continuously, will never decay. This occurs because every measurement causes the wave function to "collapse" to a pure Eigen state of the measurement basis. In the context of this effect, an "observation" can simply be the absorption of a particle, with no observer in any conventional sense. This excessive (obsessive) observation unnerves the subject to do anything but stay put, sounds like a psychological phenomenon than a quantum physical phenomenon. Recently a group of researchers from Weizmann Institute of Science in their studies of heat flow between a large thermal 'bath' and a smaller system have shown that the entropy and temperature of both the system and the bath either decrease or increase depending only on the rate of observation contrary to the laws of thermodynamics.

  1. Noam Erez1, Goren Gordon1, Mathias Nest2 & Gershon Kurizki1., Thermodynamic control by frequent quantum measurements. Nature 452, 724-727 (2008) (April 10th issue)

No comments:

Post a Comment