arXiv subjects

Carlos Pineda

Publications and source records attributed to Carlos Pineda.

38 records · Page 3Linked to original sources

arXiv2005

Evolution of pairwise entanglement in a coupled n-body system

We study the exact evolution of two non-interacting qubits, initially in a Bell state, in the presence of an environment, modeled by a kicked Ising spin chain. Dynamics of this model range from integrable to chaotic and we can handle numerics for a large number of qubits. We find that the entanglement (as measured by concurrence) of the two qubits has a close relation to the purity of the pair, and follows an analytic relation derived for Werner states. As a collateral result we find that an integrable environment causes quadratic decay of concurrence, while a chaotic environment causes linear decay.

quant-ph↗

arXiv2003

Stability of quantum Fourier transformation on Ising quantum computer

We analyze the influence of errors on the implementation of the quantum Fourier transformation (QFT) on the Ising quantum computer (IQC). Two kinds of errors are studied: (i) due to spurious transitions caused by pulses and (ii) due to external perturbation. The scaling of errors with system parameters and number of qubits is explained. We use two different procedures to fight each of them. To suppress spurious transitions we use correcting pulses (generalized $2πk$ method) while to suppress errors due to external perturbation we use an improved QFT algorithm. As a result, the fidelity of quantum computation is increased by several orders of magnitude and is thus stable in a much wider range of physical parameters.

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