Mechanism of entanglement preservation

Abstract

We study the entanglement preservation of two qubits locally interacting with their reservoirs. We show that the existence of a bound state of the qubit and its reservoir and the non-Markovian effect are two essential ingredients and their interplay plays a crucial role in preserving the entanglement in the steady state. When the non-Markovian effect is neglected, the entanglement sudden death (ESD) is reproduced. On the other hand, when the non-Markovian is significantly strong but the bound state is absent, the phenomenon of the ESD and its revival is recovered. Our formulation presents a unified picture about the entanglement preservation and provides a clear clue on how to preserve the entanglement in quantum information processing.

Quantum metrology in local dissipative environments

“…Our result is confirmable in the circuit QED platform [61], where the bound state has been observed in the photonic band-gapped environment. Note that our result is extendable to other spectral densities [55,59], where the formation mechanism of the bound state is the same. Although only the dissipative quantum metrology based on the Ramsey interferometer is studied, the revealed mechanism is applicable to both the magnetic field sensing [30] and the Mach-Zehnder interferometer [62], where the dissipation of the quantized light has the same dynamical equation as equation (5) [63].…”

“…Note that the roots of equation (11) are just the eigenenergies in the single-excitation subspace of the whole system consisting of each atom and its environment [55]. To see this, we expand the eigenstates as u e v g , 0 , 1…”

“…, which implies that the atomic dissipation is inhibited and the entanglement can be partially preserved in the steady state [55].…”

Phase-Dependent Electron-Ion Recombination in a Microwave Field

“…Collectively, these observations suggest that quasi stable Floquet states are formed in both cases, as suggested by Gurian et al and Tong et al [12,14]. In the He case, there are bound levels of He separated by frequencies close to the IR frequency, so it is easy to imagine a quasi stable wave packet based on these coupled states.…”

Measurement-Induced Nonlocality and Geometric Discord in the Spin-Boson Model

“…In contrast, quantum discord in similar conditions decays only in asymptotic time [22], which signifies that quantum discord is more robust against Markovian noise than entanglement. There are also many works involved the evolutions of quantum entanglement and discord in the non-markovian environments [23][24][25][26][27][28][29]. Especially, trapping [30] and quantum beats [31] for quantum entanglement and discord for a pair of qubits in local structured environments were found.…”