48 research outputs found
Polarization entangled photons from quantum dots embedded in nanowires
We present a first measurement of photon polarization entanglement from the
biexciton to ground state cascade of a single InAsP quantum dot embedded in an
InP nanowire. We observe a fidelity of 0.76(2) to a reference maximally
entangled state as well as a concurrence of 0.57(6)
Device-independent quantum key distribution based on Bell inequalities with more than two inputs and two outputs
Device-independent quantum key distribution (DI-QKD) offers the strongest form of security against eavesdroppers bounded by the laws of quantum mechanics. However, a practical implementation is still pending due to the requirement of combinations of visibility and detection efficiency that are beyond those possible with current technology. This mismatch motivates the search for DI-QKD protocols that can close the gap between theoretical and practical security. In this work, we present two DI-QKD protocols whose security relies on Bell inequalities with more than two inputs and two outputs. We show that, for maximally entangled states and perfect visibility, a protocol based on a Bell inequality with three inputs and four outputs requires a slightly lower detection efficiency than the protocols based on Bell inequalities with two inputs and two outputs
Multipartite entanglement in the photon number basis by sequential excitation of a three-level system
We propose a general scheme to generate entanglement encoded in the photon
number basis, via a sequential resonant two-photon excitation of a three-level
system. We apply it to the specific case of a quantum dot three-level system,
which can emit a photon pair through a biexciton-exciton cascade. The state
generated in our scheme constitutes a tool for secure communication, as the
multipartite correlations present in the produced state may provide an enhanced
rate of secret communication with respect to a perfect GHZ state.Comment: 04 pages and 04 figures. Comments are welcom