Hannover 2020 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 11: Quantum Optics I
Q 11.6: Talk
Monday, March 9, 2020, 15:15–15:30, f342
Using a genuine local oscillator for direct sampling of the Wigner function — •Johannes Tiedau1, Christof Eigner1, Victor Quiring1, Laura Padberg1, Raimund Ricken1, Benjamin Brecht1, Tim J. Bartley2, and Christine Silberhorn1 — 1Universität Paderborn, Integrierte Quantenoptik, Warburger Str. 100, D-33098 Paderborn — 2Universität Paderborn, Mesoskopische Quantenoptik, Warburger Str. 100, D-33098 Paderborn
Local oscillators are essential for quantum state characterisation and many encoding schemes in long-distance communication since they offer mode-selective and phase-sensitive measurements. Despite their name, typical experimental implementations of "local" oscillators in homodyne detection are directly derived from the laser source which generates the states, thereby opening security loopholes in quantum communication and information processing protocols. Here, we demonstrate an approach based on a genuinely local oscillator, which is generated at the receiver and hence does not suffer from this loophole. In order to show full control over our local oscillator we investigate a phase-sensitive two-mode squeezed vacuum state. Instead of standard strong field homodyning, we directly sample the Wigner function by phase-resolved photon counting. We show that this method is, in the strong squeezing regime, robust to a larger phase-jitter than standard homodyne detection.