https://doi.org/10.1140/epjd/e2012-30626-x
Regular Article
Photonic spatial Bell-state analysis for robust quantum secure direct communication using quantum dot-cavity systems
Department of Physics, Applied Optics Beijing Area
Major Laboratory, Beijing Normal University, Beijing
100875, P.R.
China
a e-mail: fgdeng@bnu.edu.cn
Received:
11
October
2012
Received in final form:
18
November
2012
Published online:
6
March
2013
Recently, experiments showed that the spatial-mode states of entangled photons are more robust than their polarization-mode states in quantum communications. Here, we construct a complete and deterministic protocol for analyzing the spatial Bell states using the interaction between a photon and an electron spin in a charged quantum dot inside a one-side micropillar microcavity. A quantum nondemolition detector (QND) for checking the parity of a two-photon system can be constructed with the giant optical Faraday rotation in this solid state system. With this parity-check QND, we present a complete and deterministic proposal for the analysis of the four spatial-mode Bell states. Moreover, we present a robust two-step quantum secure direct communication protocol based on the spatial-mode Bell states and the photonic spatial Bell-state analysis. Our analysis shows that our BSA proposal works in both the strong and the weak coupling regimes if the side leakage and cavity loss rate is small.
Key words: Quantum Information
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013