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artículo con referato
"Interpretation of Tomography and Spectroscopy as Dual Forms of Quantum Computation"
C. Miquel, J.P. Paz, M. Saraceno, E. Knill, R. Laflamme and C. Negrevergne
Nature 418(6893) (2002) 59-62
Determining the state of a system and measuring properties of its evolution are two of the most important tasks a physicist faces. For the first purpose one can use tomography, a method that after subjecting the system to a number of experiments determines all independent elements of the density matrix. For the second task, one can resort to spectroscopy, a set of techniques used to determine the spectrum of eigenvalues of the evolution operator. In this letter, we show that tomography and spectroscopy can be naturally interpreted as dual forms of quantum computation. We show how to adapt the simplest case of the well-known phase estimation quantum algorithm to perform both tasks, giving it a natural interpretation as a simulated scattering experiment. We show how this algorithm can be used to implement an interesting form of tomography by performing a direct measurement of the Wigner function (a phase space distribution) of a quantum system. We present results of such measurements performed on a system of three qubits using liquid state nuclear magnetic resonance (NMR) quantum computation techniques in a sample of trichloroethylene. Remarkable analogies with other experiments are discussed.
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