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Unformatted text preview: 1 Design and optimisation of quantum logic circuits for a three-qubit Deutsch-Jozsa algorithm implemented with optically-controlled, solid-state quantum logic gates A Del Duce, S Savory and P Bayvel Optical Networks Group, Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, UK E-mail: [email protected] Abstract. We analyse the design and optimisation of quantum logic circuits suitable for the experimental demonstration of a three-qubit quantum computation prototype based on optically-controlled, solid-state quantum logic gates. In these gates, the interaction between two qubits carried by the electron-spin of donors is mediated by the optical excitation of a control particle placed in their proximity. First, we use a geometrical approach for analysing the entangling characteristics of these quantum gates. Then, using a genetic programming algorithm, we develop circuits for the refined Deutsch-Jozsa algorithm investigating different strategies for obtaining short total computational times. We test two separate approaches based on using different sets of entangling gates with the shortest possible gate computation time which, however, does not introduce leakage of quantum information to the control particles. The first set exploits fast approximations of controlled-phase gates as entangling gates, while the other one arbitrary entangling gates with a shorter gate computation time compared to the first set. We have identified circuits with consistently shorter total computation times when using controlled-phase gates. 1 Introduction During the last years a new model of quantum computer has been developed which is based on the optically-controlled, solid-state quantum logic gates proposed by Stoneham, Fisher and Greenland in  and typically referred to as SFG gates. In this proposal the qubits are carried by the electron-spin of donors in a solid-state substrate while two-qubit interactions are mediated by a so-called control particle placed in proximity of the qubits and triggered by the excitation and de-excitation of the control particle through optical pulses. The potential of this implementation lies in the optical control of the two-qubit interactions which allows to remove noisy electrical circuitry from the quantum register and to avoid high-precision fabrication processes for the exact placement of control electrodes. After its first proposal presented in , further theoretical studies on the dynamics of SFG gates have been presented in , while in  gate parameters were identified which allow the fast implementation of entangling gates such as the C-NOT gate, for example, with minor leakage of quantum information from the qubits to the control particles. Recently, important measurements of the life-times of potential control particles in a silicon substrate have been obtained . These results are a fundamental step towards the implementation of a quantum computation prototype based on SFG quantum logic gates which represents an essential test-...
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- Spring '11
- Work, SFG, Qubit, Quantum information science, SFG gates