Temperature estimation in a quantum spin bath through entangled and separable two-qubit probes
Department of Physics, Research Unit of Condensed Matter, Electronic and Signal Processing, Dschang School of Sciences and Technology, University of Dschang, PO Box: 67, Dschang, Cameroon
Accepted: 30 January 2021
Published online: 16 February 2021
We investigate the two-qubit thermometry of a thermal spins bath using a pair of qubits in entangled or product states as a quantum probe. The probe system is coupled to the bath via a Heisenberg XY interaction. We evaluate the precision of the procedure by recourse to the quantum Fisher information and the corresponding quantum signal-to-noise ratio. We demonstrate that the use of entangled Bell states does not necessarily lead to improvements in the estimation procedure. For both short- and long-time interactions, we found that only a product state always allows us to achieve the largest estimation precision as compared to entangled Bell states.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2021