Bonn 2025 – scientific programme
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QI: Fachverband Quanteninformation
QI 42: Quantum Technologies (Color Centers and Ion Traps) II (joint session Q/QI)
QI 42.4: Talk
Friday, March 14, 2025, 12:00–12:15, HS Botanik
Entanglement by path identity based on engineered photon pairs — •Richard Bernecker1,2, Baghdasar Baghdasaryan3, and Stephan Fritzsche1,2 — 1Institute for Theoretical Physics, Friedrich Schiller University Jena, 07743 Jena, Germany — 2Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany — 3Institute of Applied Physics, Friedrich Schiller University Jena, Albert-Einstein-Str. 6, 07745 Jena, Germany
Entangled photon pairs are essential for applications in quantum communication and distributed quantum computing. A convenient approach for entanglement generation is to coherently superimpose photon pairs created in multiple nonlinear crystals via spontaneous parametric down-conversion (SPDC). The entanglement emerges because no information is available about which crystal created the pair, provided the propagation paths of the photon pairs are overlapped. This path identity approach was experimentally demonstrated by overlapping separable orbital angular momentum modes using three nonlinear crystals and spiral phase plates. However, the number of nonlinear crystals governs the dimensionality of the entangled state, posing challenges for generating entanglement in large Hilbert spaces. Recently, we explored the direct generation of maximally entangled states via pump and crystal shaping in SPDC. In this contribution, we combine pump shaping techniques with the path identity approach to engineer high-dimensional entangled states. A key advantage of this method is the potential for increasing the scalability of the entanglement dimensionality without requiring additional crystals in the setup.
Keywords: High-dimensional entanglement; Photon pairs; Spontaneous parametric down-conversion; Orbital angular momentum; Entanglement by path identity