Evolution of an Atom Impeded by Measurement: The Quantum Zeno Effect

Abstract

A quantum system being observed evolves more slowly. This "quantum Zeno effect" is reviewed with respect to a previous attempt of demonstration, and to subsequent criticism of the significance of the findings. A recent experiment on an individual cold trapped ion has been capable o f revealing the micro-state o f this quantum system, such that the effect of measurement is indeed discriminated from dephasing o f the quantum state by either the meter or the environment.

Quantum Zeno dynamics: mathematical and physical aspects

“…The discussion that followed [145,144,77,146,75,57,139,1,138,162,14,12,88,160,112,161,101,36,71,183] provided insight and new ideas, eventually leading to new experimental tests. The QZE was successfully checked in a variety of different situations, on experiments involving photon polarization [93], nuclear spin isomers [122], individual ions [10,172,188,9], optical pumping [118], NMR [189], Bose-Einstein condensates [168] and new experiments are in preparation with neutron spin [79,148] and superconducting qubits [80,178]. One should also emphasize that the first experiments were not free from interpretational problems.…”

Quantum Zeno Effect in a Model Multilevel Molecule

“…After the seminal experiment by Itano and collaborators, 4 the QZE has been experimentally verified in a variety of different situations, on experiments involving photon polarization, 14 nuclear spin isomers, 15 individual ions, [16][17][18][19] optical pumping, 20 NMR, 21 Bose-Einstein condensates, 22 the photon number of the electromagnetic field in a cavity, 23 and new experiments are in preparation with neutron spin. 24,25 We focus here on the interesting example of QZE proposed in: 15 the nuclear spin depolarization mechanisms in 13 CH 3 F, due to magnetic dipole interactions and collisions among the molecules in the gas, was experimentally investigated and interpreted as a QZE.…”

“…After the seminal experiment by Itano and collaborators, the QZE has been experimentally verified in a variety of different situations, on experiments involving photon polarization, nuclear spin isomers, individual ions, – optical pumping, NMR, Bose−Einstein condensates, and the photon number of the electromagnetic field in a cavity, and new experiments are in preparation with neutron spin. , …”