Friday, 15 August 2008

Quantum Uncollapse: Unmeasuring Things

I have recently read one of the most strangest articles on quantum physics, then again most things in quantum physics is strange. It is about two physicists, Andrew Jordan from the university of Rochester and Alexander Korotkov who's from the university of California, who are claiming to have verified something called the 'Uncollapse' hypothesis.

In the crazy world of quantum physics an object can be both a wave and a particle at the same time, they can also be in multiple locations at the same time. That is until you measure that object, which then is said to 'collapse' into a definite state and position. This weirdness is best exemplified by the famous Shrodinger's cat thought experiment. A cat is placed in a sealed box along with a flask of acid which is broken by a trigger set off by a quantum mechanical effect( the decay of a radioactive atom). Since you cannot know whether the quantum effect has triggered the breaking of the flask, you can't determine whether the cat is dead or alive. The atom could be decayed and not decayed at the same time and so the cat could be both alive and dead at the same time. Until you peek inside the box, in which case the cat will definitely be in one of those states.

It was widely believed that once you make a measurement of an object you cause it to 'collapse' into a definite state, but the two physicists hypothesized and later demonstrated that it is possible to weakly measure a object, which would cause its quantum state to collapse, but if you then 'unmeasure' the object it would revert back to its original quantum state. I know what your thinking, how the hell do you 'unmeasure' something? Well, the way they did it was to apply the same weak measurements again and the particle would go back to its original state as if no measurement has taken place. What they have shown is that there is no sharp line dividing the quantum world and the classical world and that changing from one state to another takes time.

The first thing that came to mind when I read this article is if you can unmeasure something, and thus returning it to its unmeasured state, does this render quantum encryption useless?


1 comment:

  1. If one tried to "unmeasure" the double slit experiment by destroying the results of the measurement before it had been observed by a conscious being and before a conscious being had observed the pattern on the screen, would that "uncollapse" the wave function and restore the interference pattern?