15 research outputs found
Hybrid waveguide-bulk multi-path interferometer with switchable amplitude and phase
We design and realise a hybrid interferometer consisting of three paths based
on integrated as well as on bulk optical components. This hybrid construction
offers a good compromise between stability and footprint on one side and means
of intervention on the other. As experimentally verified by the absence of
higher-order interferences, amplitude and phase can be manipulated in all paths
independently. In conjunction with single photons, the setup can, therefore, be
applied for fundamental investigations on quantum mechanics.Comment: accepted in APL Photonic
Observation of genuine three-photon interference
Multiparticle quantum interference is critical for our understanding and
exploitation of quantum information, and for fundamental tests of quantum
mechanics. A remarkable example of multi-partite correlations is exhibited by
the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles
are correlated while no pairwise correlation is found. The manifestation of
these strong correlations in an interferometric setting has been studied
theoretically since 1990 but no three-photon GHZ interferometer has been
realized experimentally. Here we demonstrate three-photon interference that
does not originate from two-photon or single photon interference. We observe
phase-dependent variation of three-photon coincidences with 90.5 \pm 5.0 %
visibility in a generalized Franson interferometer using energy-time entangled
photon triplets. The demonstration of these strong correlations in an
interferometric setting provides new avenues for multiphoton interferometry,
fundamental tests of quantum mechanics and quantum information applications in
higher dimensions.Comment: 7 pages, 7 figure
Time-bin entangled photon pairs from Bragg-reflection waveguides
This work was supported by the Austrian Science Fund (FWF) through the project nos. I 2065 and J 4125, the DFG project no. SCHN1376/2-1, the ERC project EnSeNa (257531), the State of Bavaria and China Scholarship Council (201503170272).Semiconductor Bragg-reflection waveguides are well-established sources of correlated photon pairs as well as promising candidates for building up integrated quantum optics devices. Here, we use such a source with optimized non-linearity for preparing time-bin entangled photons in the telecommunication wavelength range. By taking advantage of pulsed state preparation and efficient free-running single-photon detection, we drive our source at low pump powers, which results in a strong photon-pair correlation. The tomographic reconstruction of the state’s density matrix reveals that our source exhibits a high degree of entanglement. We extract a concurrence of 88.9(1.8)% and a fidelity of 94.2(9)% with respect to a Bell state.Publisher PDFPeer reviewe