2007/08/31 by Bahar Mehmani, B. Mehmani, A. E. Allahverdyan +2
Computer Science · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Information and Cryptography #Quantum Mechanics and Applications #cond-mat.stat-mech #quant-ph
paper · pdf · doi:10.1103/physreva.77.032122
7 pages, 8 figure, Phys. Rev. A
arxiv created 2008/01/31 · openalex publication_date 2008/03/31 · arxiv updated 2012/05/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
The density matrix of a two-level system (spin, atom) is usually determined by measuring the three noncommuting components of the Pauli vector. This density matrix can also be obtained via the measurement data of two commuting variables, using a single apparatus. This is done by coupling the two-level system to a mode of radiation field, where the atom-field interaction is described with the Jaynes-Cummings model. The mode starts its evolution from a known coherent state. The unknown initial state of the atom is found by measuring two commuting observables: the population difference of the atom and the photon number of the field. We discuss the advantages of this setup and its possible applications.