Quantum model of a solid-state spin qubit: Ni cluster on a silicon surface by the generalized spin Hamiltonian and X-ray absorption spectroscopy investigations

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:394

Article

Farberovich, Oleg V.^1,2,3  Mazalova, Victoria L.²  Soldatov, Alexander V.² 

[1] Tel Aviv Univ, Beverly & Raymond Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel

[2] Southern Fed Univ, Res Ctr Nanoscale Struct Matter, Rostov Na Donu 344090, Russia

[3] Voronezh State Univ, Voronezh 394000, Russia

关键词: Spin structure;    Qubits;    X-ray absorption spectroscopy;    Density Functional Theory;    Entanglement;    Rabi oscillations;   

DOI  :  10.1016/j.jmmm.2015.06.069

来源: Elsevier

【 摘 要 】

We present here the quantum model of a Ni solid-state electron spin qubit on a silicon surface with the use of a density-functional scheme for the calculation of the exchange integrals in the non-collinear spin configurations in the generalized spin Hamiltonian (GSH) with the anisotropic exchange coupling parameters linking the nickel ions with a silicon substrate. In this model the interaction of a spin qubit with substrate is considered in GSH at the calculation of exchange integrals Li of the nanosystem in the one-electron approach taking into account chemical bonds of all Si-atoms of a substrate (environment) with atoms of the Ni-7-cluster. The energy pattern was found from the effective GSH Hamiltonian acting in the restricted spin space of the Ni ions by the application of the irreducible tensor operators (ITO) technique. In this paper we offer the model of the quantum solid-state N-spin qubit based on the studying of the spin structure and the spin-dynamics simulations of the 3d-metal Ni clusters on the silicon surface. The solution of the problem of the entanglement between spin states in the N-spin systems is becoming more interesting when considering clusters or molecules with a spectral gap in their density of states. For quantifying the distribution of the entanglement between the individual spin eigenvalues (modes) in the spin structure of the N-spin system we use the density of entanglement (DOE). In this study we have developed and used the advanced high precision numerical techniques to accurately assess the details of the decoherence process governing the dynamics of the N-spin qubits interacting with a silicon surface. We have studied the Rabi oscillations to evaluate the N-spin qubits system as a function of the time and the magnetic field. We have observed the stabilized Rabi oscillations and have stabilized the quantum dynamical qubit state and Rabi driving after a fixed time (0.327 mu s). The comparison of the energy pattern with the anisotropic exchange models conventionally used for the analysis of this system and, with the results of the experimental XANES spectra, shows that our complex investigations provide a good description of the pattern of the spin levels and the spin structures of the nanomagnetic Ni-7 qubit. The results are discussed in the view of the general problem of the solid-state spin qubits and the spin structure of the Ni cluster. (C) 2015 Elsevier EN. All rights reserved

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