Universal and measurable entanglement entropy in the spin-boson model

الأصل · EN

We study the entanglement between a qubit and its environment from the spin-boson model with Ohmic dissipation. Through a mapping to the anisotropic Kondo model, we derive the entropy of entanglement of the spin E(α,Δ,h), where α is the dissipation strength, Δ is the tunneling amplitude between qubit states, and h is the level asymmetry. For 1-α≫ Δ/ωc and (Δ,h) ≪ ωc, we show that the Kondo energy scale Tₖ controls the entanglement between the qubit and the bosonic environment (ωc is a high-energy cutoff). For h≪ Tₖ, the disentanglement proceeds as (h/Tₖ)²; for h≫ Tₖ, E vanishes as (Tₖ/h)²⁻²α, up to a logarithmic correction. For a given h, the maximum entanglement occurs at a value of α which lies in the crossover regime h Tₖ. We emphasize the possibility of measuring this entanglement using charge qubits subject to electromagnetic noise.