2006/02/06 by G. Chiappe, E. Louis, E. Louis y E. V. Anda +1 · 2 citations
Computer Science · Physics and Astronomy · #Condensed matter physics #Exchange interaction #Exciton #Ferromagnetism #Hamiltonian (control theory) #Photon #Physics #Polariton #Quantum #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum dot #Quantum mechanics #Qubit #Spins #Strong Light-Matter Interactions #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.74.155320
published in Physical Review B 74(15) (American Physical Society) · 7 figures, submitted to PRB
arxiv created 2006/02/06 · openalex publication_date 2006/10/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate coupling of localized spins in a semiconductor quantum dot embedded in a microcavity with a finite quality factor. The lowest cavity mode and the quantum dot exciton are coupled forming a polariton, whereas excitons interact with localized spins via exchange. The finite quality of the cavity Q is incorporated in the model Hamiltonian by adding an imaginary part to the photon frequency. The Hamiltonian, which treats photons, spins and excitons quantum mechanically, is solved exactly. Results for a single polariton clearly demonstrate the existence of a resonance, sharper as the temperature decreases, that shows up as an abrupt change to and fro between ferromagnetic and antiferromagnetic indirect anisotropic exchange interaction between localized spins. The origin of this spin-switching finite-quality-factor effect is discussed in detail remarking on its dependence on model parameters, i.e., light-matter coupling, exchange interaction between impurities, detuning and quality factor. For parameters corresponding to the case of a (Cd,Mn)Te quantum dot, the resonance shows up for Q\ensuremath≈140 and detuning around 10\phantom\rule0.3em0exmeV. In addition, we show that, for such a quantum dot, and the best cavities actually available (quality factors better than 200) the exchange interaction is scarcely affected.