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THU: Thursday Contributed Sessions
THU 13: Poster Session: Applications
THU 13.42: Poster
Thursday, September 11, 2025, 16:30–18:30, ZHG Foyer 1. OG
Multistep Two-Copy Distillation of Squeezed States via Two-Photon Subtraction — •Stephan Grebien1, Julian Göttsch1, Boris Hage2, Jaromír Fiurášek3, and Roman Schnabel1 — 1Institut für Quantenphysik & Zentrum für Optische Quantentechnologien (ZOQ), , Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany — 2Institut für Physik, Universität Rostock, 18051 Rostock, Germany — 3Department of Optics, Faculty of Science, Palacký University, 17. listopadu 12, 77900 Olomouc, Czech Republic
Squeezed states of light are a vital resource in quantum computing and quantum cryptography. The higher the amount of squeezing available the greater the quantum advantage.
The squeeze factor is mainly limited by the effective nonlinearity of the medium and optical loss. In our experiment we analyzed the multi-step distillation of weakly squeezed states of light increasing the squeeze factor from 2.4 dB to 2.8 dB and finally 3.4 dB. The first step was purely experimental and achieved by conditioning the measurement on a 2-photon subtraction event.
For the second step we simultaneously measured the squeezed and the anti-squeezed quadratures of the already distilled state and probabilistically emulated a second two-copy distillation step. This provided data as it would be measured on a 3.4-dB squeezed state. We theoretically found out that multi-step two-copy distillation allows the increase of the squeeze factor beyond the limits set by the effective nonlinearity and in the ideal case even an infinite squeeze factor.
Keywords: quantum optics; squeezed states of light; photon subtraction; two copy distillation