Quantum zeno effect

[ecculs]

Can someone plz tell me what the quantum zeno effect is?

[Klaynos]

http://en.wikipedia.org/wiki/Quantum_Zeno_effect

 

Far better than I could do as I've lost my copy of rae :'(

 

It's in my room somewhere!

[Gilded]

Now there's an interesting effect. So basically if you had a box (well, an electromagnetic trap sort of box) of very unstable particles that were under frequent measuring, the decay rate suddenly increase when the measuring stops... right?

[swansont]

Now there's an interesting effect. So basically if you had a box (well, an electromagnetic trap sort of box) of very unstable particles that were under frequent measuring, the decay rate suddenly increase when the measuring stops... right?

 

Right, although the experiments with which I am familiar are atomic transitions, not nuclear decay, so there are other transitions you can measure that re-set the decay clock, so to speak. I'm not sure to what extent that's possible in nuclear decay.

 

In atomic systems you can view de-excitation as coupling into a mode of the vacuum, which means that you can affect the decay rate by changing the density of vacuum states. People have sped up the relaxation or suppressed it in cavity QED experiments. Again, I'm not sure if the model for nuclear decay incorporates this.

[5614]

Reminds me of a great experiment, it is the quantum version of watching a kettle boil. That is, they excite electrons from one state to a higher one. However if they observe the electrons whilst they are being excited then they cannot change state whilst being observed.

 

Instead of trying to explain the experiment in detail I've scanned in 3 pages from Schrödinger's Kittens and the Search for Reality, by John Gribbin, which gives details of the experiment.

 

First page:

http://img.photobucket.com/albums/v601/5614/quantumpot1.png

Second and third page:

http://img.photobucket.com/albums/v601/5614/quantumpot2.png

 

Incidentally this is an experiment that produces the results it does due the quantum Zeno effect. If you don't understand yet then you may want to understand it before you read through that. Ask here if you have any questions!