2006/12/31 by Angela Kopp, Karyn Le Hur · 3 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.98.220401
published as Phys. Rev. Lett. 98, 220401 (2007) · 4 pages and 4 figures; updated version to appear in Physical Review Letters
arxiv created 2007/05/08 · openalex publication_date 2007/05/31 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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(\ensuremathα,\ensuremathΔ,h), where \ensuremathα is the dissipation strength, \ensuremathΔ is the tunneling amplitude between qubit states, and h is the level asymmetry. For 1\ensuremath-\ensuremathα\ensuremath≫\ensuremathΔ/\ensuremathωc and (\ensuremathΔ,h)\ensuremath≪\ensuremathωc, we show that the Kondo energy scale TK controls the entanglement between the qubit and the bosonic environment (\ensuremathωc is a high-energy cutoff). For h\ensuremath≪TK, the disentanglement proceeds as (h/TK)2; for h\ensuremath≫TK, E vanishes as (TK/h)^2\ensuremath-2\ensuremathα, up to a logarithmic correction. For a given h, the maximum entanglement occurs at a value of \ensuremathα which lies in the crossover regime h\ensuremath∼TK. We emphasize the possibility of measuring this entanglement using charge qubits subject to electromagnetic noise.