Perturbative approach for the dynamics of the quantum Zeno subspaces (7 pages)

B. Kaulakys, Julius Ruseckas

Saverio Pascazio, Paolo Facchi A, Daniel A. Lidar

Mei Zhang, Li You

Paolo Facchi A, Rosario Fazio, Giuseppe Florio +2 more

Yi-Xin Chen, Zhuowen Fang

We investigate the dynamics of the quantum Zeno subspaces which are the eigenspaces of the interaction Hamiltonian, belonging to different eigenvalues. Using the perturbation theory and the adiabatic approximation, we get a general expression of the jump probability between different Zeno subspaces. We applied this result in an interesting practical example. In this example, as the coupling constant of the interaction increases, the measurement keeps the system remaining in its initial subspace and the quantum Zeno effect takes place.

Léa Ferreira dos Santos, F. Borgonovi, G. L. Celardo

In recent experiments with ion traps, long-range interactions were associated with the exceptionally fast propagation of perturbation, while in some theoretical works they have also been related with the suppression of propagation. Here, we show that such apparently contradictory behavior is caused by a general property of long-range interacting systems, which we name cooperative shielding. It refers to shielded subspaces that emerge as the system size increases and inside of which the evolution is unaffected by long-range interactions for a long time. As a result, the dynamics strongly depends on the initial state: if it belongs to a shielded subspace, the spreading of perturbation satisfies the Lieb-Robinson bound and may even be suppressed, while for initial states with components in various subspaces, the propagation may be quasi-instantaneous. We establish an analogy between the shielding effect and the onset of quantum Zeno subspaces. The derived effective Zeno Hamiltonian successfully describes the short-ranged dynamics inside the subspaces up to a time scale that increases with system size. Cooperative shielding can be tested in current experiments with trapped ions.