2013/10/10 by Tomasz Wasak, Jan Chwedeńczuk, Wasak, T. +5
Computer Science · Economics, Econometrics and Finance · #FOS: Physical sciences #Quantum Information and Cryptography #Quantum Physics (quant-ph) #Stochastic processes and financial applications
paper · pdf · doi:10.48550/arxiv.1310.2844
openalex publication_date 2013/10/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We identify optimal measurement strategies for phase estimation in different scenarios. For pure states of a single qubit, we show that optimal measurements form a broad set parametrized with a continuous variable. When the state is mixed this set reduces to merely two possible measurements. For two qubits, we focus on the symmetric Werner state. We find an optimal measurement and show that estimation from the population imbalance is optimal only if the state is pure. Finally, for a pure state of N qubits, we finds under which conditions the estimation from the full N-body correlation and from the population imbalance are optimal.