Perspectives on the quantum Zeno paradox

As of October 2006, there were approximately 535 citations to the seminal1977 paper of Misra and Sudarshan that pointed out the quantum Zeno paradox(more often called the quantum Zeno effect). In simple terms, the quantum Zenoeffect refers to a slowing down of the evolution of a quantum state in thelimit that the state is observed continuously. There has been much disagreementas to how the quantum Zeno effect should be defined and as to whether it isreally 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 mostoften called a demonstration of the quantum Zeno effect. Given that there isdisagreement as to what the quantum Zeno effect is, there naturally isdisagreement as to whether that experiment demonstrated the quantum Zenoeffect. Some differing perspectives regarding the quantum Zeno effect and whatwould constitute an experimental demonstration are discussed.