# SAMOP 2023 – wissenschaftliches Programm

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# QI: Fachverband Quanteninformation

## QI 36: Quantum Metrology (joint session QI/Q)

### QI 36.2: Vortrag

### Freitag, 10. März 2023, 11:15–11:30, F428

**Activation of metrologically useful genuine multipartite entanglement** — •Róbert Trényi^{1,2,3}, Árpád Lukács^{1,4,3}, Paweł Horodecki^{5,6}, Ryszard Horodecki^{5}, Tamás Vértesi^{7}, and Géza Tóth^{1,2,8,3} — ^{1}Dept. of Theoretical Physics, U. of the Basque Country UPV/EHU, Bilbao, Spain — ^{2}DIPC, San Sebastián, Spain — ^{3}Wigner Research Centre for Physics, Budapest, Hungary — ^{4}Dept. of Mathematical Sciences, Durham University, United Kingdom — ^{5}International Centre for Theory of Quantum Technologies, University of Gdansk, Gdansk, Poland — ^{6}Faculty of Applied Physics and Mathematics, National Quantum Information Centre, Gdansk University of Technology, Gdansk, Poland — ^{7}Institute for Nuclear Research, Debrecen, Hungary — ^{8}IKERBASQUE, Bilbao, Spain

In quantum metrology, the usefulness of a quantum state is determined by how much it outperforms separable states. For the maximal metrological usefulness genuine multipartite entanglement (GME) is required. In order to improve the usefulness of a quantum state we consider a scheme of having several of its copies. With this scheme, it is possible to find a large class of practically important entangled states that can achieve maximal metrological performance in the limit of many copies, whereas in the single copy case these states can even be non-useful. Thus, we essentially activate quantum metrologically useful GME. Moreover, this maximal usefulness is attained exponentially fast with the number of copies and it can be achieved by measurements of simple correlation observables. We also give examples of improving the usefulness outside of the above mentioned class.