Search results for " zeno effect"
showing 10 items of 18 documents
Microscopic description of dissipative dynamics of a level-crossing transition
2011
We analyze the effect of a dissipative bosonic environment on the Landau-Zener-Stuckelberg-Majorana (LZSM) level crossing model by using a microscopic approach to derive the relevant master equation. For an environment at zero temperature and weak dissipation our microscopic approach confirms the independence of the survival probability on the decay rate that has been predicted earlier by the simple phenomenological LZSM model. For strong decay the microscopic approach predicts a notable increase of the survival probability, which signals dynamical decoupling of the initial state. Unlike the phenomenological model our approach makes it possible to study the dependence of the system dynamics…
A Realistic Proposal for the Observation of Zeno Phenomena in the Dynamics of Trapped Ions
2001
A realistic experimental scheme for the observation of a continuous measurement Quantum Zeno Effect in the contest of single trapped ions is proposed. Our method relies on the nonlinearities characterizing the ionic Rabi frequency far from the Lamb-Dicke regime.
Non-Gaussian correlations imprinted by local dephasing in fermionic wires
2020
We study the behavior of an extended fermionic wire coupled to a local stochastic field. Since the quantum jump operator is Hermitian and quadratic in fermionic operators, it renders the model soluble, allowing investigation of the properties of the non-equilibrium steady-state and the role of dissipation-induced fluctuations. We derive a closed set of equations of motion solely for the two-point correlator; on the other hand, we find, surprisingly, that the many-body state exhibits non-Gaussian correlations. Density-density correlation function demonstrates a crossover from a regime of weak dissipation characterized by moderate heating and stimulated fluctuations to a quantum Zeno regime r…
Ramsey interferometry of non-Hermitian quantum impurities
2020
We introduce a Ramsey pulse scheme which extracts the non-Hermitian Hamiltonian associated to an arbitrary Lindblad dynamics. We propose a realted protocol to measure via interferometry a generalised Loschmidt echo of a generic state evolving in time with the non-Hermitian Hamiltonian itself, and we apply the scheme to a one-dimensional weakly interacting Bose gas coupled to a stochastic atomic impurity. The Loschmidt echo is mapped into a functional integral from which we calculate the long-time decohering dynamics at arbitrary impurity strengths. For strong dissipation we uncover the phenomenology of a quantum many-body Zeno effect: corrections to the decoherence exponent resulting from t…
Driven Appearance and Disappearance of Quantum Zeno Effect in the Dynamics of a Four-level Trapped Ion
2001
An example of constrained unitary quantum dynamics in the context of trapped ions is given. We study a laser driven four-level ion system confined in an isotropic three-dimensional Paul microtrap. Our main result is that when two independent controllable continuous measurement processes are simultaneously present, the unitary quantum dynamics of the system can be parametrically frozen into a one-dimensional Hilbert subspace (Quantum Zeno Effect) or constrained into a two-dimensional one, at will. Conditions under which one of the two processes acts upon the physical system inhibiting the effects due to the other one, are explicitly found and discussed (Hierarchically Controlled Dynamics).
Competition of continuous and projective measurements in filtering processes
2016
A quantum system interacting with a repeatedly measured one turns out to be subjected to a non-unitary evolution which can force the former to a specific quantum state. It is shown that in the case where the repeatedly measured system is subjected to the action of its environment, the occurrence of a competition between the dissipation and the measurements can reduce the influence of the decay on the filtering process. Both theoretical predictions and numerical results are presented.
Zeno dynamics and high-temperature master equations beyond secular approximation
2013
Complete positivity of a class of maps generated by master equations derived beyond the secular approximation is discussed. The connection between such class of evolutions and physical properties of the system is analyzed in depth. It is also shown that under suitable hypotheses a Zeno dynamics can be induced because of the high temperature of the bath.
Stimulated Raman adiabatic passage in an open quantum system: Master equation approach
2010
A master equation approach to the study of environmental effects in the adiabatic population transfer in three-state systems is presented. A systematic comparison with the non-Hermitian Hamiltonian approach [N. V. Vitanov and S. Stenholm, Phys. Rev. A {\bf 56}, 1463 (1997)] shows that in the weak coupling limit the two treatments lead to essentially the same results. Instead, in the strong damping limit the predictions are quite different: in particular the counterintuitive sequences in the STIRAP scheme turn out to be much more efficient than expected before. This point is explained in terms of quantum Zeno dynamics.
Sensitivity of Measurement-Based Purification Processes to Inner Interactions
2017
The sensitivity of a repeated measurement-based purification scheme to additional undesired couplings is analyzed, focusing on the very simple and archetypical system consisting of two two-level systems interacting with a repeatedly measured one. Several regimes are considered and in the strong coupling (i.e., when the coupling constant of the undesired interaction is very large) the occurrence of a quantum Zeno effect is proven to dramatically jeopardize the efficiency of the purification process.
Two-qubit entanglement generation through non-Hermitian Hamiltonians induced by repeated measurements on an ancilla
2020
In contrast to classical systems, actual implementation of non-Hermitian Hamiltonian dynamics for quantum systems is a challenge because the processes of energy gain and dissipation are based on the underlying Hermitian system&ndash