Speaker
Description
Long-distance quantum communication can potentially suffer under decoherence of the photonic state in optical fibers. In comparison to polarization entanglement, time-bin entanglement is remarkably robust in fibers, which is an essential property for the implementation and usage of long-distance quantum information protocols such as quantum key distribution. In time-bin entanglement, the photons are entangled with respect to the time-bin in which they are created.
Generating these photon pairs requires precise temporal control of a photon pair source. Several proposals exist on how time-bin entangled photon pairs can be created from quantum emitters. For the generation of the entangled state, semiconductor quantum dots are our system of choice, as they provide on-demand generation of photon pairs with a high yield. Additionally, the presence of optically dark exciton states in quantum dots allow for the deterministic preparation of time-bin entangled states [1]. These dark states that can be addressed using tilted magnetic fields and strongly chirped pulses [2]. An experimentally simpler approach relies on probabilistic generation, using sequential excitation of the biexciton state, addressing the biexciton in a two-photon resonant process [3].
On this poster, we introduce the theoretical background for the numerical simulation of time-bin entanglement. This includes the multi-time correlation functions calculated from the full time dynamics of the quantum dot excitation [4]. We apply these techniques to simulate the degree of time-bin entanglement achieved by a scheme relying on dark excitons and compare it to the previously used probabilitstic generation scheme. Our results are another crucial step to bright time-bin entanglement from quantum dots.
References
[1] C. Simon and J.-P. Poizat, Phys. Rev. Lett. 94, 030502 (2005)
[2] F. Kappe, R. Schwarz, Y. Karli, T. Bracht et al., arXiv:2404.10708 (2024)
[3] H. Jayakumar et al., Nat. Communications, 5, 4251, (2014)
[4] T. Bracht, F. Kappe, M. Cygorek et al., arXiv:2404.08348 (2024)
