Here a fixed-point duality quantum search algorithm is proposed.This algorithm uses iteratively non-unitary operations and measurements to search an unsorted database.Once the marked item is found,the algorithm stops automatically.This algorithm uses a constant non-unitary operator,and requires N/4 steps on average(N is the number of data from the database) to locate the marked state.The implementation of this algorithm in a usual quantum computer is also demonstrated.
HAO Liang1,LIU Dan2 & LONG GuiLu1,3 1Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics,Tsinghua University,Beijing 100084,China
The four-body interaction plays an important role in many-body systems, and it can exhibit interesting phase transition behaviors. In this letter, we report the experimental demonstration of a four-body interaction in a four-qubit nuclear magnetic resonance quantum information processor. The strongly modulating pulse is used to implement spin selective excitation. The results show a good agreement between theory and experiment.
A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2003, 68: 022306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity.
HAO Liang1, LI JunLin1 & LONG GuiLu1,2 1Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics, Tsinghua University, Beijing 100084, China
