594 citations · 1.3k across the 7 of their papers we have counts for
7 papers
Interferometric autocorrelation in the ultra-violet utilizing spontaneous parametric down-conversion
Patrick Michelberger, Roland Krischek, Witlef Wieczorek +2
Autocorrelation is a common method to estimate the duration of ultra-short laser pulses. In the ultra-violet (UV) regime it is increasingly challenging to employ the standard proce…
Useful Multiparticle Entanglement and Sub-Shot-Noise Sensitivity in Experimental Phase Estimation
Roland Krischek, Christian Schwemmer, Witlef Wieczorek +4
We experimentally demonstrate a general criterion to identify entangled states useful for the estimation of an unknown phase shift with a sensitivity higher than the shot-noise lim…
Fisher information and multiparticle entanglement
Philipp Hyllus, Wiesław Laskowski, Roland Krischek +5
The Fisher information gives a limit to the ultimate precision achievable in a phase estimation protocol. It has been shown recently that the Fisher information for a linear tw…
Permutationally invariant quantum tomography
Geza Toth, Witlef Wieczorek, David Gross +3
We present a scalable method for the tomography of large multiqubit quantum registers. It acquires information about the permutationally invariant part of the density operator, whi…
Practical methods for witnessing genuine multi-qubit entanglement in the vicinity of symmetric states
Geza Toth, Witlef Wieczorek, Roland Krischek +3
We present general numerical methods to construct witness operators for entanglement detection and estimation of the fidelity. Our methods are applied to detecting entanglement in…
Experimental entanglement of a six-photon symmetric Dicke state
Witlef Wieczorek, Roland Krischek, Nikolai Kiesel +3
We report on the experimental observation and characterization of a six-photon entangled Dicke state. We obtain a fidelity as high as 0.6540.024 and prove genuine six-photon e…