Quantum state stability against decoherence

Abstract

We study the stability of the coherence of a state of a quantum system under the effect of an interaction with another quantum system at short time. We find an expression for evaluating the order of magnitude of the time scale for the onset of instability as a function of the initial state of both involved systems and of the sort of interaction between them. As an application we study the spin-boson interaction in the dispersive interaction regime, driven by a classical field. We find, for this model, that the behavior of the time scale for the onset of instability, with respect to the boson bath temperature, changes depending on the intensity of the classical field.

Sufficient and Necessary Condition for Zero Quantum Entropy Rates under any Coupling to the Environment

“…Starting from this point of view that assumes that the system undergoes open quantum system dynamics [2][3][4], the entropy of quantum systems can be preserved from decoherence. Symmetries of the dynamics can be exploited [5][6][7][8][9] or dynamical operations can be performed [10][11][12] to stabilize the entropy of a system . We depart from that approach that focuses on the structure of the open system dynamics with an unknown environment and the standard approximations that go with it. Instead, we take the point of view of studying the structure of the total system-environment states ρ SE and their relationship to the system decoherence.…”

“…Starting from this point of view that assumes that the system undergoes open quantum system dynamics [2][3][4], the entropy of quantum systems can be preserved from decoherence. Symmetries of the dynamics can be exploited [5][6][7][8][9] or dynamical operations can be performed [10][11][12] to stabilize the entropy of a system.…”

“…Effectively, they lead to closed system dynamics for very short times, independent of the details of the Hamiltonian coupling [38]. The class of lazy states is also different from the concept of subdecoherent states and decoherence-free subspaces [5][6][7][8][9][10][11][12], as lazy states are independent from the particular symmetries of the dynamics. Lazy states are a natural consequence of dynamical stability of the entropy measure under arbitrary open system dynamics, connecting the dynamical properties of reduced systems S to the structure of the total SE state [15,16].…”

Two-qubit Grover search in a dephasing-free subspace in cavity QED

“…For example, for the cavity QED system, we hope it can do as much quantum information work as possible-preparation of entangled states, quantum state transfer, quantum search algorithms, even quantum computation-under similar setup conditions. Compatible QIP is one direction in which researchers should develop, under the quantum state stability analysis against decoherence [14] and the single-photon interaction to induce efficient multiparty entanglement [15]. In our scheme for qubits encoded in pairs of atoms in the DFS, we can implement the transfer and teleportation of quantum states [6] and the preparation of entangled states [5].…”

Linearly independent pure-state decomposition and quantum state discrimination

“…The fundamental property of a pure state is that it can always be expressed as a coherent superposition of linearly independent states which, for instance, gives account of the accurate quantum interference phenomenon [2]. If the system is not isolated then, in general, it is correlated with an uncontrollable quantum system, usually called environment, which introduces decoherence to the state of the system [3]. In this case the effective state of the system can be described by a mixed state which consists of an incoherent superposition of possible states.…”