Quantum Zeno Survival
Compare coherent survival with the product of repeated projective survival events.
Free theory articleCompare coherent survival with the product of repeated projective survival events.
Concept & interpretation
The Quantum Zeno effect occurs when repeated measurements of a quantum system slow down or freeze its coherent evolution. Consider a resonantly driven two-level system starting in the state |0>. Without any measurement, the probability of finding the system in |0> at time T (where T is controlled via T/π) is cos2(T/2).
Investigating measurement frequency
Open the Quantum Zeno Survival module and use the controls to observe the effect of repeated measurements.
- Set Measurements to 1 and Time over pi to 1. The all-survival probability matches the unmeasured survival probability at 0, since a single measurement at T = π just confirms the complete transfer to the other state.
- Increase Measurements to 4. As calculated in the example, the all-survival probability rises to roughly 0.53079.
- Change Measurements to 16. The all-survival probability increases further to roughly 0.85687. This demonstrates the Quantum Zeno effect: increasing the frequency of measurements inhibits the system from leaving the initial state.
- Notice that the infinite-frequency limit is always 1 for any fixed finite T. If N approaches infinity, the all-survival probability [cos2(T/(2N))]N approaches 1.