SCIENCE SPIN-OFFS

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Phonon Decoherence of Quantum Dots in Photonic Structures: Broadening of the Zero-Phonon Line and the Role of Dimensionality

Petru Tighineanu, Chris L. Dreeßen, Christian Flindt, Peter Lodahl, Anders S. Sørensen
(Submitted on 15 Feb 2017 (v1), last revised 12 Jan 2018 (this version, v2))

We develop a general microscopic theory describing the phonon decoherence of quantum dots and indistinguishability of the emitted photons in photonic structures. The coherence is found to depend fundamentally on the dimensionality of the structure resulting in vastly different performance for quantum dots embedded in a nano-cavity (0D), waveguide (1D), slab (2D), or bulk medium (3D). In bulk, we find a striking temperature dependence of the dephasing rate scaling as T11 implying that phonons are effectively 'frozen out' for T? 4 K. The phonon density of states is strongly modified in 1D and 2D photonic structures leading to a linear temperature scaling for the dephasing strength. The resulting impact on the photon indistinguishability can be important even at sub-Kelvin temperatures. Our findings provide a comprehensive understanding of the fundamental limits to photon indistinguishability in photonic structures.

https://arxiv.org/abs/1702.04812