Dissipation and entanglement dynamics for two interacting qubits coupled to independent reservoirs

Abstract

Abstract.We derive the master equation of a system of two coupled qubits by taking into account their interaction with two independent bosonic baths. Important features of the dynamics are brought to light, such as the structure of the stationary state at general temperatures and the behaviour of the entanglement at zero temperature, showing the phenomena of sudden death and sudden birth as well as the presence of stationary entanglement for long times. The model here presented is quite versatile and can be of interest in the study of both Josephson junction architectures and cavity-QED.

Robust stationary entanglement of two coupled qubits in independent environments

“…Besides confirming many features previously reported in the literature [21,22,23,24,25,26,27,28,29,30,31,32,33,34], our analysis showed that these terms produce long-time stationary entanglement [35,36,37]. The next natural task is thus to look for effects stemming from nonzero reservoir temperatures.…”

“…We have presented a general solution of a decay model for two interacting qubits, each one coupled to a different bosonic reservoir, previously solved in the zero-temperature only [35]. The analysis reported here clearly shows that the counter-rotating terms in the qubit-qubit interaction, usually neglected via a rotating wave approximation, cause two distinct physical effects, still observable at reasonable experimental temperatures (typically of the order of 10 ÷ 20 mK).…”

“…In reference [35], a master equation was derived for the case in which each qubit interacts with an independent bosonic thermal bath. Indeed, by using the general formalism given in reference [39], under the secular approximation and the assumption of independent bosonic reservoirs, the Markovian master equation governing the dynamics of the qubit-qubit system turns out to be:…”

“…[35]. ¿From equations (14) it is possible to evaluate the effects of nonzero reservoir temperatures on the entanglement.…”

Dissipative effects on a generation scheme of a W state in an array of coupled Josephson junctions

“…Moreover in Ref. [24] the reservoirs are assumed to be independent, which is justified in the case of spatially separated Josephson qubits, since the noise in each device is due to impurities belonging to different parts of the whole superconducting circuit.…”