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As you might know, the Zeno effect is intuitively expressed as what happens when a system is measured in intervals smaller than the half life of the state it is currently on. As a consequence, the state has a negligible probability of doing a transition and is kept 'stuck' in its current state, making the effective evolution operator the identity.

I don't know an equivalent picture for the Anti-Zeno effect. Under what conditions does it happen and why? does the above picture is merely interpretational or is fully accurate at a fundamental level?

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up vote 2 down vote accepted

The Anti-Zeno effect is when you have a transition from a state enhanced by a decoherence source. I can show you a toy model where it happens:

consider four states A,B,E and Z. Z is the ground state, and A and B are two nearly degenerate excited states and E is a super-excited. B has no matrix element to Z and A has matrix elements to Z. Then start the system in A, and keep measuring if you are in B by shining a laser tuned to the B-E transition. The system will, through the ordinary Zeno effect, be stuck in A, and then will decay to Z through the A->Z transition.

If you turn off the laser, the system will oscillate between A and B, and will only decay in the A portion.

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