Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 89: Focus Session: Quantum Information Systems (jointly with MA,TT)

HL 89.6: Vortrag

Donnerstag, 29. März 2012, 18:00–18:15, ER 164

Entangled photons from the polariton vacuum in a switchable optical cavity — •Adrian Auer and Guido Burkard — Department of Physics, University of Konstanz, D-78457 Konstanz, Germany

We study theoretically the entanglement of two-photon states in the ground state of the intersubband cavity system, the so-called polariton vacuum. The system is formed by a sequence of doped quantum wells (QWs) located inside a microcavity and the photons can interact with intersubband excitations inside the QWs, which leads to the formation of polariton states. In the ultrastrong coupling regime, the polariton vacuum already contains a finite number of photons. In an explicit solution for the polariton vacuum, we only consider certain two-photon states by post-selection and analyze them for mode entanglement. We find an analytical expression for the entanglement using the concurrence and it depends on the absolute values of the in-plane wave vectors of the photons. For photon energies around the intersubband resonance in the mid infrared regime, the photons are almost maximally entangled, what is fundamentally important for their possible use in quantum information processing. Furthermore, there exists a continuous set of mode pairs, for which the photons are maximally entangled.