# SAMOP 2021 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# QI: Fachverband Quanteninformation

## QI 9: Quantum Metrology

### QI 9.3: Vortrag

### Donnerstag, 23. September 2021, 11:45–12:00, H4

Activating hidden metrological usefulness — •Géza Tóth^{1,2,3,4}, Tamás Vértesi^{5}, Paweł Horodecki^{6,7}, and Ryszard Horodecki^{6,8} — ^{1}Theoretical Physics, University of the Basque Country UPV/EHU, E-48080 Bilbao, Spain — ^{2}Donostia International Physics Center (DIPC), E-20080 San Sebastián, Spain — ^{3}IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — ^{4}Wigner Research Centre for Physics, H-1525 Budapest, Hungary — ^{5}Institute for Nuclear Research, Hungarian Academy of Sciences, H-4001 Debrecen, Hungary — ^{6}International Centre for Theory of Quantum Technologies, University of Gdańsk, PL-80308 Gdańsk, Poland — ^{7}Faculty of Applied Physics and Mathematics, National Quantum Information Centre, Gdańsk University of Technology, PL-80233 Gdańsk, Poland — ^{8}Institute of Theoretical Physics and Astrophysics, National Quantum Information Centre, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, PL-80308 Gdańsk, Poland

We consider entangled states that cannot outperform separable states in any linear interferometer. Then, we show that these states can still be more useful metrologically than separable states if several copies of the state are provided or an ancilla is added to the quantum system. We present a general method to find the local Hamiltonian for which a given quantum state performs the best compared to separable states.