Quantum Quasi-Zeno Dynamics: Transitions mediated by frequent projective measurements near the Zeno regime

TL;DR

This paper explores how frequent measurements in quantum systems can induce transitions via virtual processes outside the Zeno subspace, leading to new dynamical effects described by effective Hamiltonians.

Contribution

It introduces a framework for understanding higher-order virtual processes in quantum Zeno dynamics and derives effective Hamiltonians to describe these phenomena.

Findings

Transitions mediated by virtual states are possible near the Zeno regime.

Effective Hamiltonians depend on measurement frequency.

Application to spin chains and optical lattices shows correlated dynamics.

Abstract

Frequent observation of a quantum system leads to quantum Zeno physics, where the system evolution is constrained to states commensurate with the measurement outcome. We show that, more generally, the system can evolve between such states through higher-order virtual processes that pass through states outside the measurement subspace. We derive effective Hamiltonians to describe this evolution, and the dependence on the time between measurements. We demonstrate application of this phenomena to prototypical quantum many-body system examples, spin chains and atoms in optical lattices, where it facilitates correlated dynamical effects.