  Controlled full adder-subtractor by vibrational computing; ; Remacle, Françoise  et alin Physical Chemistry Chemical Physics [=PCCP] (2010), 12(48), 15628-15635 Detailed reference viewed: 6 (2 ULg)Controlled full adder or subtractor by vibrational quantum computing; ; Remacle, Françoise et alin Physical Review. A (2009), 80(2), A controlled full addition or subtraction can be realized by a unitary transformation on a register of four qubits. The fourth qubit is then used as a control qubit to enforce the addition or the ... [more ▼] A controlled full addition or subtraction can be realized by a unitary transformation on a register of four qubits. The fourth qubit is then used as a control qubit to enforce the addition or the subtraction of two binary digits and a carry or a borrow. The transformation can be decomposed into six elementary gates. The network differs from the adder network of four elementary gates by including two new controlled-NOT gates. The scheme is general and its implementation using vibrational computing has the advantage that the single global transformation that connects the inputs to the outputs can be driven in one step by a single laser shot. This decreases the time of operation and allows for a better use of the optical resources and for an improvement of the fidelity. The laser pulses are optimized by optimal control theory. [less ▲] Detailed reference viewed: 50 (6 ULg)Computational investigation and experimental considerations for the classical implementation of a full adder on SO2 by optical pump-probe schemes; ; Remacle, Françoise et alin Journal of Chemical Physics (2008), 128(19), Following the scheme recently proposed by Remacle and Levine [Phys. Rev. A 73, 033820 (2006)], we investigate the concrete implementation of a classical full adder on two electronic states ((X) over tilde ... [more ▼] Following the scheme recently proposed by Remacle and Levine [Phys. Rev. A 73, 033820 (2006)], we investigate the concrete implementation of a classical full adder on two electronic states ((X) over tilde (1)A(1) and (C) over tilde B-1(2)) of the SO2 molecule by optical pump-probe laser pulses using intuitive and counterintuitive (stimulated Raman adiabatic passage) excitation schemes. The resources needed for providing the inputs and reading out are discussed, as well as the conditions for achieving robustness in both the intuitive and counterintuitive pump-dump sequences. The fidelity of the scheme is analyzed with respect to experimental noise and two kinds of perturbations: The coupling to the neighboring rovibrational states and a finite rotational temperature that leads to a mixture for the initial state. It is shown that the logic processing of a full addition cycle can be realistically experimentally implemented on a picosecond time scale while the readout takes a few nanoseconds. (c) 2008 American Institute of Physics. [less ▲] Detailed reference viewed: 7 (1 ULg)Vibrational computing: Simulation of a full adder by optimal control; ; Remacle, Françoise et alin Journal of Chemical Physics (2008), 128(6), Within the context of vibrational molecular quantum computing, we investigate the implementation of a full addition of two binary digits and a carry that provides the sum and the carry out. Four qubits ... [more ▼] Within the context of vibrational molecular quantum computing, we investigate the implementation of a full addition of two binary digits and a carry that provides the sum and the carry out. Four qubits are necessary and they are encoded into four different normal vibrational modes of a molecule. We choose the bromoacetyl chloride molecule because it possesses four bright infrared active modes. The ground and first excited states of each mode form the one-qubit computational basis set. Two approaches are proposed for the realization of the full addition. In the first one, we optimize a pulse that implements directly the entire addition by a single unitary transformation. In the second one, we decompose the full addition in elementary quantum gates, following a scheme proposed by Vedral [Phys. Rev. A 54, 147 (1996)]. Four elementary quantum gates are necessary, two two-qubit CNOT gates (controlled NOT) and two three-qubit TOFFOLI gates (controlled-controlled NOT). All the logic operations consist in one-qubit flip. The logic implementation is therefore quasiclassical and the readout is based on a population analysis of the vibrational modes that does not take the phases into account. The fields are optimized by the multitarget extension of the optimal control theory involving all the transformations among the 2(4) qubit states. A single cycle of addition without considering the preparation or the measure or copy of the result can be carried out in a very competitive time, on a picosecond time scale. (C) 2008 American Institute of Physics. [less ▲] Detailed reference viewed: 18 (3 ULg) |
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