Thermal equilibrium as an initial state for quantum computation by NMR

Amr F. Fahmy, Raimund Marx, Wolfgang Bermel, Steffen J. Glaser

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An experimental implementation of an ensemble quantum algorithm is presented in which the thermal state is used as an initial state of the algorithm. More specifically, we use four active qubits to demonstrate the solution of the Deutsch-Jozsa problem using a nuclear magnetic resonance quantum computer. For the implemented algorithm the number of molecules in the NMR sample is irrelevant to the number of qubits available to an NMR quantum computer, and the initial state is chosen to be the state of thermal equilibrium, thereby avoiding the preparation of pseudopure states and the resulting exponential loss of signal as the number of qubits increases. As expected, measured spectra demonstrate a clear distinction between constant and balanced functions.

Original languageEnglish
Article number022317
JournalPhysical Review A
Issue number2
StatePublished - 12 Aug 2008


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