Quantum anti-Zeno effect without wave function reduction

TL;DR

This paper investigates the quantum anti-Zeno effect using a coupling-based measurement approach, demonstrating that frequent quasi-measurements induce exponential decay similar to traditional projection measurements, without wave function collapse.

Contribution

It introduces a quasi-measurement framework based on couplings rather than wave function reduction, showing equivalence in decay rates and survival probabilities.

Findings

Quasi-measurements induce exponential decay similar to projection measurements.

Survival probability matches that of traditional measurement approaches.

Photon emission following each quasi-measurement confirms the measurement process.

Abstract

We study the measurement-induced enhancement of the spontaneous decay (called quantum anti-Zeno effect) for a two-level subsystem, where measurements are treated as couplings between the excited state and an auxiliary state rather than the von Neumann's wave function reduction. The photon radiated in a fast decay of the atom, from the auxiliary state to the excited state, triggers a quasi-measurement, as opposed to a projection measurement. Our use of the term "quasi-measurement" refers to a "coupling-based measurement". Such frequent quasi-measurements result in an exponential decay of the survival probability of atomic initial state with a photon emission following each quasi-measurement. Our calculations show that the effective decay rate is of the same form as the one based on projection measurements. What is more important, the survival probability of the atomic initial state which is obtained by tracing over all the photon states is equivalent to the survival probability of the atomic initial state with a photon emission following each quasi-measurement to the order under consideration. That is because the contributions from those states with photon number less than the number of quasi-measurements originate from higher-order processes.