Extending NMR Quantum Computation Systems by Employing Compounds with Several Heavy Metals as Qubits

Abstract

Nuclear magnetic resonance (NMR) is a spectroscopic method that can be applied to several areas. Currently, this technique is also being used as an experimental quantum simulator, where nuclear spins are employed as quantum bits or qubits. The present work is devoted to studying heavy metal complexes as possible candidates to act as qubit molecules. Nuclei such 113Cd, 199Hg, 125Te, and 77Se assembled with the most common employed nuclei in NMR-QIP implementations (1H, 13C, 19F, 29Si, and 31P) could potentially be used in heteronuclear systems for NMR-QIP implementations. Hence, aiming to contribute to the development of future scalable heteronuclear spin systems, we specially designed four complexes, based on the auspicious qubit systems proposed in our previous work, which will be explored by quantum chemical calculations of their NMR parameters and proposed as suitable qubit molecules. Chemical shifts and spin–spin coupling constants in four complexes were examined using the spin–orbit zeroth-order regular approximation (ZORA) at the density functional theory (DFT) level, as well as the relaxation parameters (T1 and T2). Examining the required spectral properties of NMR-QIP, all the designed complexes were found to be promising candidates for qubit molecules.

Theory and computation of nuclear shielding

“…In 2022 Aucar et al 33 developed an LRESC-Loc model to analyze magnetic shieldings with localized molecular orbitals. Kaupp et al 34 reported on evaluation of modern DFT approaches for the computation of nuclear shieldings of 3d transition-metal nuclei and Sauer et al 35 extended NMR quantum computation systems by employing compounds with several heavy metals as qubits. Makulski, Aucar and Aucar 36 studied experimentally and theoretically ammonia in order to establish 14 N and 15 N absolute shielding scales.…”

On the geometry dependence of the nuclear magnetic resonance chemical shift of mercury in thiolate complexes: A relativistic density functional theory study

“…The usefulness of ZORA calculations of NMR parameters for heavy elements has been shown and reviewed in many studies. [16][17][18][19][20][21][22][23][24][25][26][27][28] Arcisauskaite et al, for example, have previously investigated relativistic effects on Hg chemical shifts in mercury halide compounds. [16] A comparison between three methods were reported: the fully relativistic four-component approach, linear response elimination of small component (LR-ESC), [29,30] and ZORA.…”

“…An alternative option are the computationally less demanding two‐component methods [10–15] such as the zeroth‐order regular approximation (ZORA) method. The usefulness of ZORA calculations of NMR parameters for heavy elements has been shown and reviewed in many studies [16–28] . Arcisauskaite et al, for example, have previously investigated relativistic effects on Hg chemical shifts in mercury halide compounds [16] .…”