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The quantum Zeno effect is a quantum mechanical phenomenon first described by E.C. George Sudarshan and Baidyanaith Misra of the University of Texas in 1977. It describes that situation that an unstable particle, if observed continuously, will never decay. This occurs because every measurement causes the wavefunction to " collapse" to a pure eigenstate of the measurement basis. Say if measurements are made periodically, with some finite interval between each one. At each measurement, the wavefunction collapses to a pure state. Between the measurements, the system evolves away from the pure state into a mixed state. When the mixed state is measured, it will again collapse, either back into the same state as the first measurement, or away into one of the other states. The probability that it will collapse back into the same state is higher if the system has had less time to evolve away from it. In the limit as the time between measurements goes to zero, the probability of collapse back to the original state goes to one. Hence, the system doesn't evolve.
In reality, collapse of the wavefunction is not a discrete, instantaneous event. A measurement could be approximated by strongly coupling the quantum system to the noisy thermal environment for a brief period of time. The time it takes for the wavefunction to "collapse" is related to the decoherence time of the system when coupled to the environment. The stronger the coupling is, and the shorter the decoherence time, the faster it will collapse. So in the decoherence picture, the quantum Zeno effect corresponds to the limit where a quantum system is continuously coupled to the environment, and where that coupling is infinitely strong, and where the "environment" is an infinitely large source of thermal randomness.
Experimentally, strong suppression of the evolution of a quantum system due to environmental coupling has been observed in a number of microscopic systems. One such experiment was performed in October 1989 by Itano , Heinzen , Bollinger and Wineland at NIST (PDF). Approximately 5000 9 Be+ ions were stored in a cylindrical Penning trap and laser cooled to below 250mK. A resonant RF pulse was applied which, if applied alone, would cause the entire ground state population to migrate into an excited state. After the pulse was applied, the ions were monitored for photons emitted due to relaxation. The ion trap was then regularly "measured" by applying a sequence of ultraviolet pulses, during the RF pulse. As expected, the ultraviolet pulses suppressed the evolution of the system into the excited state. The results were in good agreement with theoretical models.
The reason we can't use the Zeno effect as a science-fiction-like stasis fieldA stasis field is an imaginary phenomenon that is often used in science fiction that slows the passage of time inside it, or stops it entirely. Stasis fields in these fictional settings often have several common characteristics. These include infinite or to freeze large objects is because there is no way to couple them so strongly to the environment. Ordinary molecular forces are clearly insufficient. A much easier way to freeze a large object would be to cool it down to near absolute zeroAbsolute zero is the lowest temperature that can be obtained in any macroscopic system. Absolute temperature means temperature measured on a scale with absolute zero as 0. This is conventionally measured in kelvin, which is the Celsius degree scale with a. At absolute zero the system is in its ground state and there is no macroscopic evolution. This is known as the third law of thermodynamicsThe third law of thermodynamics was developed by Walther Nernst and is thus sometimes referred to as Nernst's theorem . This states that the entropy of a system at zero absolute temperature is a well-defined constant. This is because a system at zero temp. Note that the Zeno effect allows a system to be frozen into an excited state, not just the ground state, so in some sense it is more versatile.
The quantum Zeno effect takes its name from Zeno's arrow paradoxZeno's paradoxes are a set of paradoxes conceived by Zeno of Elea to support Parmenides's doctrine that all evidence of the senses is misleading, and particularly that there is no motion. Several of Zeno's eight surviving paradoxes (preserved in Aristotle, which is the argument that since an arrow in flight does not move during any single instant, it couldn't possibly be moving overall.
