  As of October 2006, there were approximately 535 citations to the seminal
1977 paper of Misra and Sudarshan that pointed out the quantum Zeno paradox
(more often called the quantum Zeno effect). In simple terms, the quantum Zeno
effect refers to a slowing down of the evolution of a quantum state in the
limit that the state is observed continuously. There has been much disagreement
as to how the quantum Zeno effect should be defined and as to whether it is
really a paradox, requiring new physics, or merely a consequence of "ordinary"
quantum mechanics. The experiment of Itano, Heinzen, Bollinger, and Wineland,
published in 1990, has been cited around 347 times and seems to be the one most
often called a demonstration of the quantum Zeno effect. Given that there is
disagreement as to what the quantum Zeno effect is, there naturally is
disagreement as to whether that experiment demonstrated the quantum Zeno
effect. Some differing perspectives regarding the quantum Zeno effect and what
would constitute an experimental demonstration are discussed.
