SAMOP 2021 – scientific programme
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QI: Fachverband Quanteninformation
QI 9: Quantum Metrology
QI 9.3: Talk
Thursday, September 23, 2021, 11:45–12:00, H4
Activating hidden metrological usefulness — •Géza Tóth1,2,3,4, Tamás Vértesi5, Paweł Horodecki6,7, and Ryszard Horodecki6,8 — 1Theoretical Physics, University of the Basque Country UPV/EHU, E-48080 Bilbao, Spain — 2Donostia International Physics Center (DIPC), E-20080 San Sebastián, Spain — 3IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — 4Wigner Research Centre for Physics, H-1525 Budapest, Hungary — 5Institute for Nuclear Research, Hungarian Academy of Sciences, H-4001 Debrecen, Hungary — 6International Centre for Theory of Quantum Technologies, University of Gdańsk, PL-80308 Gdańsk, Poland — 7Faculty of Applied Physics and Mathematics, National Quantum Information Centre, Gdańsk University of Technology, PL-80233 Gdańsk, Poland — 8Institute 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.