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QI: Fachverband Quanteninformation
QI 14: Quantum Information Poster Session
QI 14.11: Poster
Mittwoch, 11. März 2026, 18:00–21:00, P4
Differential magnetometry with partially flipped Dicke states — •Iagoba Apellaniz1,2, Manuel Gessner3, and Géza Tóth1,2,4,5,6 — 1Department of Theoretical Physics, University of the Basque Country UPV/EHU, P. O. Box 644, ES-48080 Bilbao, Spain — 2EHU Quantum Center, University of the Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao, Spain — 3Departament de Física Teòrica, IFIC, Universitat de València, CSIC, Carrer del Dr. Moliner 50, 46100 Burjassot (València), Spain — 4Donostia International Physics Center DIPC, Paseo Manuel de Lardizabal 4, San Sebastián, E-20018, Spain — 5IKERBASQUE, Basque Foundation for Science, E-48009 Bilbao, Spain — 6HUN-REN Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
Dicke states on two ensembles can be sensitive to magnetic gradients by locally rotating the spins on one well. We determine bounds for the precision for gradient metrology in the three orthogonal directions as a function of the sensitivities of the homogenous field. The resulting partially flipped Dicke state saturates these bounds. Exploiting entanglement between the two ensembles, this state achieves roughly twice the precision attainable by the best bipartite separable state, which is a product of local Dicke states. For small ensembles, we explicitly identify measurement operators saturating the quantum Cramér-Rao bound, while for larger ensembles, we propose simpler schemes. The gradient is estimated from second moments of local angular momentum operators. Our results demonstrate how metrological properties of Dicke states can be exploited for quantum-enhanced estimation.
Keywords: Quantum Metrology; Quantum Entanglement; Differential Quantum Metrology; Multiparametric Quantum Metrology