Abstract
In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. The effect is conventionally controlled by the measurement frequency. Here we study the development of the Zeno regime as a function of the measurement strength for a continuous partial measurement. We show that the onset of the Zeno regime is marked by a $\textit{cascade of transitions}$ in the system dynamics as the measurement strength is increased. Some of these transitions are only apparent in the collective behavior of individual quantum trajectories and are invisible to the average dynamics. They include the appearance of a region of dynamically inaccessible states and of singularities in the steady-state probability distribution of states. These newly predicted dynamical features, which can be readily observed in current experiments, show the coexistence of fundamentally unpredictable quantum jumps with those continuously monitored and reverted in recent experiments.
Highlights
The evolution of a quantum system under measurement is inherently stochastic due to the intrinsic quantum fluctuations of the detector [1]
We show that the onset of the Zeno regime is marked by a cascade of transitions in the system dynamics as the measurement strength is increased
By investigating the full stochastic dynamics of quantum trajectories, we show that the quantum Zeno regime is established via a cascade of transitions in the system dynamics, some being invisible to the average dynamics
Summary
The evolution of a quantum system under measurement is inherently stochastic due to the intrinsic quantum fluctuations of the detector [1]. The above-mentioned transitions stem from the basic physics of the quantum Zeno effect [27,28] In this regime, as a result of repeated measurements, the system state is mostly frozen next to one of the measurement eigenstates, yet rarely performs quantum jumps between them. We study the transition between the regimes of coherent oscillations and Zeno-like dynamics in a qubit subject to continuous partial measurements [see Fig. 1(a)], a model directly describing some recent experiments [26]. Our results provide a unified picture of the onset of the Zeno regime arising from continuous partial measurements and demonstrate that investigating individual quantum trajectories can uncover drastically new physics even in simple and well-studied systems.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
