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Numerical simulation of coherent transport in quantum wires for quantum computing

Andrea Bertoni, Paolo Bordone, ROSSELLA BRUNETTI +2 more

A solid-state implementation of a universal set of gates for quantum computation is proposed and analysed using a time-dependent 2D Schrödinger solver. The qubit is defined as the state of an electron propagating along a couple of quantum wires. The wires are suitably coupled through a potential barrier with variable height and/or width. It is shown how a proper design of the system allows the implementation of any one-qubit transformation. The two-qubit gate is realized through a Coulomb coupler able to entangle the quantum states of two electrons running in two wires of two different qubits. The simulated devices are GaAs—AlGaAs heterostructures that should be on the borderline of present semiconductor technology. An estimate of decoherence effects due to phonon scattering is also presented.A solid-state implementation of a universal set of gates for quantum computation is proposed and analysed using a time-dependent 2D Schrödinger solver. The qubit is defined as the state of an electron propagating along a couple of quantum wires. The wires are suitably coupled through a potential barrier with variable height and/or width. It is shown how a proper design of the system allows the implementation of any one-qubit transformation. The two-qubit gate is realized through a Coulomb coupler able to entangle the quantum states of two electrons running in two wires of two different qubits. The simulated devices are GaAs—AlGaAs heterostructures that should be on the borderline of present semiconductor technology. An estimate of decoherence effects due to phonon scattering is also presented.

Journal of Modern OpticsJul 1, 200221 citations

Impurity effects in quantum wires

G. Gómez-Santos

Springer eBooksApr 6, 20080 citations

Quantum teleportation of electrons in quantum wires with surface acoustic waves

Fabrizio Buscemi, Paolo Bordone, Andrea Bertoni

We propose and numerically simulate a semiconductor device based on coupled quantum wires, suitable for deterministic quantum teleportation of electrons trapped in the minima of surface acoustic waves. We exploit a network of interacting semiconductor quantum wires able to provide the universal set of gates for quantum information processing with the qubit defined by the localization of a single electron in one of two coupled channels. The numerical approach is based on a time-dependent solution of the three-particle Schr\"odinger equation. First, a maximally entangled pair of electrons is obtained via Coulomb interaction between carriers in different channels. Then, a complete Bell-state measurement involving one electron from this pair and a third electron is performed. Finally, the teleported state is reconstructed by means of local one-qubit operations. The large estimated fidelity explicitly suggests that an efficient teleportation process could be reached in an experimental setup.We propose and numerically simulate a semiconductor device based on coupled quantum wires, suitable for deterministic quantum teleportation of electrons trapped in the minima of surface acoustic waves. We exploit a network of interacting semiconductor quantum wires able to provide the universal set of gates for quantum information processing with the qubit defined by the localization of a single electron in one of two coupled channels. The numerical approach is based on a time-dependent solution of the three-particle Schr\"odinger equation. First, a maximally entangled pair of electrons is obtained via Coulomb interaction between carriers in different channels. Then, a complete Bell-state measurement involving one electron from this pair and a third electron is performed. Finally, the teleported state is reconstructed by means of local one-qubit operations. The large estimated fidelity explicitly suggests that an efficient teleportation process could be reached in an experimental setup.

arXiv:0910.4288Physical Review BJan 14, 201023 citations

Transport in quantum wires

Amir Yacoby

Springer eBooksSep 28, 20072 citations

On the Existence of Stoner Instability in a Semiconductor Electron Quantum Wire

Vinayak Garg, Rajinder Kumar Moudgil, Alka B. Garg +2 more

Motivated by the recent experimental evidence of the Stoner instability in a semiconductor quantum wire, we have theoretically examined the spin phase diagram of such a wire by comparing the ground‐state energy in the states of different spin polarization. To this endeavour, the self‐consistent mean‐field approximation of Singwi et al. has been used. The transverse motion of electrons is assumed to be confined by a cylindrically symmetric harmonic potential. Our study predicts a transition to the ferromagnetic phase at a sufficiently low electron density, thus corroborating the experimental scenario. Further, the partially spin‐polarized phases are found to be unstable‐ a prediction in agreement with the recent quantum Monte Carlo simulations.Motivated by the recent experimental evidence of the Stoner instability in a semiconductor quantum wire, we have theoretically examined the spin phase diagram of such a wire by comparing the ground‐state energy in the states of different spin polarization. To this endeavour, the self‐consistent mean‐field approximation of Singwi et al. has been used. The transverse motion of electrons is assumed to be confined by a cylindrically symmetric harmonic potential. Our study predicts a transition to the ferromagnetic phase at a sufficiently low electron density, thus corroborating the experimental scenario. Further, the partially spin‐polarized phases are found to be unstable‐ a prediction in agreement with the recent quantum Monte Carlo simulations.

AIP conference proceedingsJan 1, 20110 citations

Quantum theory of mesoscopic electric circuits in entangled state representation

Hong-Yi Fan, Yue Fan, Song Tong-Qiang

Physics Letters ADec 1, 200220 citations

Simulation of entangled electronic states in semiconductor quantum wires

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