2025/01/16 by Göttsch, Julian, Grebien, Stephan, Pein, Felix +6
#FOS: Physical sciences #Optics (physics.optics) #Quantum Physics (quant-ph)
paper · doi:10.48550/arxiv.2501.09424
Microscopic Schrödinger cat states are generated from quantum correlated fields using a probabilistic heralding photon subtraction event. Subsequent quantum state tomography provides complete information about the state with typical photon numbers of the order of one. Another approach strives for a larger number of quantum-correlated photons by conditioning the measurement analysis on events with exactly this number of photons. Here, we present a new approach to derive measurement data of quantum correlated states with average quantum-correlated photon numbers significantly larger than one. We produce an ensemble of a heralded, photon-subtracted squeezed vacuum state of light. We split the states at a balanced beam splitter and simultaneously measure a pair of orthogonal field quadratures at the outputs using tomographic `Q-function homodyne detection' (QHD). The final act is probabilistic two-copy data post-processing aiming for data from a new state with larger photon number. Evaluating the final tomographic data as that of a grown microscopic Schrödinger cat state shows that the probabilistic post-processing increased the photon number of |α0|2 ≈ 1.2 to |α2|2 ≈ 6.8. Our concept for obtaining tomographic measurement data of mesoscopic non-classical states that never existed might be a turning point in measurement-based quantum technology.