Complete disentanglement by partial pure dephasing

Abstract

We study the effect of pure dephasing on the entanglement of a pair of two-level subsystems (qubits). We show that partial dephasing induced by a super-Ohmic reservoir, corresponding to well-established properties of confined charge states and phonons in semiconductors, may lead to complete disentanglement. We show also that the disentanglement effect increases with growing distance between the two subsystems.Comment: Final, considerably extended version, 6 pages, 4 figure

Temperature-independent teleportation of qubits in Davies environments

“…Let us notice that the pure dephasing serves as a good approximation of various models studied in wide range of contexts [19,21,22]. Relationship between temperature dependence of the fidelity and the particular choice of initial preparation is well visible in, otherwise not very interesting for teleportation, long time limit lim t→∞ F. In Fig.…”

Analytically solvable model for the entanglement via scattering-like mechanisms

“…29 holds true when ω(t) attains its limits ω ± sufficiently fast for t → ±∞, respectively. The quantity σ in (29) can be obtained from the long-time solution x(t) of the equation of motion x + ω 2 (t)x = 0 of a classical oscillator with the frequency ω(t) by imposing a proper boundary condition for x(t) as t → −∞. Because ω(t) → ω + for t → ∞, we expect that for t → ∞ the solution takes the form…”

“…The operators H ± characterize the subsystem E as well as the details of the interaction between Q and E [2,18]. Note that in a general case the qubit is asymmetrically coupled to the subsystem E. Despite its simplicity, this model has already been applied to study a wide spectrum of various problems like a quantum kicked rotator, chaotic dynamics of a periodically driven superconducting single electron transistor and the Josephson flux qubit [12,24,27,29]. The evolution operator U (t, t 0 ) of the composite system can explicitly be evaluated since the block-diagonal form for the time-shift operator is preserved:…”

The sudden death of entanglement in constructed Yang–Baxter systems

“…This phenomenon is called entanglement sudden death (ESD). The surprising phenomenon of ESD, contrary to intuition which is based on experience about qubit decoherence, has attracted much attention recently [7][8][9][10][11][12][13][14].…”