Tensor train optimization of parametrized quantum circuits

We examine a particular realization of derivative-free method as implemented on tensor train based optimization to the variational quantum eigensolver. As an example, we consider parametrized quantum circuits composed of a low-depth hardware-efficient ansatz and Hamiltonian variational ansatz for addressing the ground state of the transverse field Ising model. We further make a comparison with gradient-based optimization techniques and discuss on the advantage of using tensor train based optimization, especially in the presence of noise.Comment: 7 pages, 5 figure

Fractional Marcus-Hush-Chidsey-Yakopcic current-voltage model for redox-based resistive memory devices

We propose a circuit-level model combining the Marcus-Hush-Chidsey electron current equation and the Yakopcic equation for the state variable for describing resistive switching memory devices of the structure metal-ionic conductor-metal. We extend the dynamics of the state variable originally described by a first-order time derivative by introducing a fractional derivative with an arbitrary order between zero and one. We show that the extended model fits with great fidelity the current-voltage characteristic data obtained on a Si electrochemical metallization memory device with Ag-Cu alloy.Comment: 7 pages, 3 figure

Spin-Density Correlations and Short-Range Order in Metals above the Curie Temperature

In the dynamic spin-fluctuation theory, we calculate the effective and local magnetic moments and spatial spin-density correlator. Our theoretical results are demonstrated by the example of bcc Fe. The effective and local moments are found in good agrement with results of polarized neutron scattering experiment over a wide temperature range. The calculated short-range order is small (up to 5 Å) and slowly decreases with temperatur

Spin-Density Correlations and Short-Range Order in Metals above the Curie Temperature

In the dynamic spin-fluctuation theory, we calculate the effective and local magnetic moments and spatial spin-density correlator. Our theoretical results are demonstrated by the example of bcc Fe. The effective and local moments are found in good agrement with results of polarized neutron scattering experiment over a wide temperature range. The calculated short-range order is small (up to 5 Å) and slowly decreases with temperatur