Grover search tested by NMR

As discussed in the Chapter 3, the quantum search algorithm is one of the most important for quantum computation. It is used to search for one or more specific quantum states in an uniform superposition. It is often compared to a search of a name (or number) in a disordered list. The main feature of this algorithm is the operation, performed by the oracle , which labels the state (or states) to be searched, by inverting its (their) phase. The second operation is the inversion about the mean value, i.e. the amplitude of each state in the system. These two operations must be applied to the system a certain number of times, which depends on the number of items one is looking for and the total number of elements on the system. For a two qubit system, the number of searches is only 1. Another important application is the ability to use this algorithm for searching the solution of a specific problem, which can be done by preparing the action of the oracle operator. 

Almost simultaneously to the publication of Chuang, Gershenfeld and Kubinec, Jones, Mosca and Hansen [9] also reported an implementation of Grover search algorithm. They used the two hydrogen nuclei in partially deuterated cytosine as a quantum computer of two qubits. However, their analysis did not included tomographed density matrices. 

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