We present integrated sources of polarization entanglement built on portable platforms for quantum communication. We employ type-II degenerate spontaneous parametric down conversion processes in periodically poled potassium titanyl phosphate (PPKTP) waveguides to generate pairs of orthogonally polarized photons at near-infrared wavelengths. We use balanced non-polarizing beam splitter (NPBS) to generate post-selected polarization-entangled states via coincidence measurements and investigate the power and spectral tunability of the system. The small size of the waveguides allows the installation of several units on the same platform, and thereby the generation of multiple entangled states simultaneously. We built a separate platform containing a computer-controlled tomography system to characterize the produced states and another NPBS is installed to combine photons from adjacent waveguides and assess their interferability, a prerequisite to entanglement swapping. The overall experiment is compact and requires little alignment when set, making it an attractive option for local quantum networking using mobile platforms, e.g., drones or satellites.
We present integrated sources of polarization entanglement built on portable platforms for quantum communication. We employ type-II degenerate spontaneous parametric down conversion processes in PPKTP waveguides to generate pairs of orthogonally polarized photons at near-infrared wavelengths. The photons are sent to a 50/50 non-polarizing beam splitter (NPBS) to generate post-selected polarization-entangled states via coincidence measurements. The small size of the waveguides allows the installation of several units on the same platform, and thereby the generation of multiple entangled states simultaneously. We use a computer-controlled tomography system to characterize the produced states and combine the photons from adjacent waveguides on another NPBS to perform Bell-state measurements, a prerequisite to entanglement swapping. The overall experiment is compact and requires little alignment when set, making it an attractive option for local quantum networking using mobile platforms, e.g., drones or satellites.
We discuss two novel entanglement sources utilizing spontaneous parametric downconversion in periodically poled waveguides. Using quasi-phase matched KTP crystals, we have demonstrated a post-selection-based polarization entangled degenerate source at 810 nm, as well as a post-selection-free non-degenerate collinear source producing entangled photons at 810 nm and 1550 nm. The sources exhibit high brightness and state quality – with the non-degenerate source achieving fidelities and purities up to 99% – with clear paths for further improvement. Furthermore, they are compact, stable, and need little alignment when set, critical for practical quantum communication and network applications. Lastly, their small size, weight, and power (SWaP) makes them an attractive option for mobile platforms, e.g., with drones or satellites.
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