Quantum Zeno effect and light - dark periods for a single atom

Abstract

The quantum Zeno effect (QZE) predicts a slow-down of the time development of a system under rapidly repeated ideal measurements, and experimentally this was tested for an ensemble of atoms using short laser pulses for non-selective state measurements. Here we consider such pulses for selective measurements on a single system. Each probe pulse will cause a burst of fluorescence or no fluorescence. If the probe pulses were strictly ideal measurements, the QZE would predict periods of fluorescence bursts alternating with periods of no fluorescence (light and dark periods) which would become longer and longer with increasing frequency of the measurements. The non-ideal character of the measurements is taken into account by incorporating the laser pulses in the interaction, and this is used to determine the corrections to the ideal case. In the limit, when the time ∆t between the laser pulses goes to zero, no freezing occurs but instead we show convergence to the familiar macroscopic light and dark periods of the continuously driven Dehmelt system. An experiment of this type should be feasible for a single atom or ion in a trap.

Protecting subspaces by acting on the outside

“…As a consequence of the quantum Zeno effect, it therefore remains there for a relatively long time. On average, this time equals Ω 2 /Γξ 2 which is much larger than 1/ξ [32]. In other words, the system exhibits a macroscopic dark period.…”

Extending the validity range of quantum optical master equations

“…The purpose of an atomic master equation is to establish a direct connection between ρ AI (t + ∆t) in Eq. (36) and ρ AI (t) in Eq. (33) without having to calculate the trace over the free radiation field after each time step ∆t.…”

Quantum Zeno and anti-Zeno effects in the Friedrichs model

“…The QZE has been discussed for many physical systems including atomic physics [10][11][12][13], radioactive decay [14], mesoscopic physics [15][16][17][18], and has been even proposed as a way to control decoherence for effective quantum computations [19]. Recently, however, a quantum anti-Zeno effect has been found [20,21].…”