Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond

Abstract

Defect quantum bits (qubits) constitute an important emerging technology. However, it is necessary to explore new types of defects to enable large-scale applications. In this article, we examine the potential of magnesium-vacancy (MgV) in diamond to operate as a qubit by computing the key electronic- and spin properties with robust theoretical methods. We find that the electronic structure of MgV permits the coexistence of two loosely separated spin-states, where both can emerge as a ground state and be interconverted depending on the temperature and external strain. These results demonstrate a route to control the magneto-optical response of a qubit by modulating the operational conditions.

Magnesium-Vacancy Optical Centers in Diamond

“…The analysis also showed previously unexplored emission properties, including the occurrence of a previously unreported line at 608.3 nm at cryogenic temperatures, compatible with the 2 A 1u → 2 E g transition predicted in ref , and the persistence of the 544.8 nm emission under all the considered excitation wavelengths in undoped substrates (in disagreement with the results in ref ).…”

“…Two defect configurations, which could be responsible for such Mg lattice sites, are Mg inside a triple vacancy or inside a quadruple vacancy, which corresponds to the so-called MgV 2 or MgV 3 complexes (possible structures for these complexes are shown in Figure S3 of the Supporting Information). MgV 2 was theoretically considered, and it was found to have a somewhat higher energy of formation than MgV, which was predicted to be the thermodynamically most stable Mg defect, followed by substitutional Mg. We note, however, that in the case of ion implantation, the energy for vacancy creation in the sample is provided by the implantation process; hence, the fact that MgV exhibits the lowest defect formation energy may not be the single determining factor which regulates the abundance of complexes formed, and thus, also Mg centers requiring triple or quadruple vacancies might be commonly found. The MgV 2 center was predicted to have a similar configuration to MgV, with an additional vacancy “attached from the side” and a symmetry lowering to C 1 (although no detailed Mg coordinates were published) .…”

“…MgV 2 was theoretically considered, and it was found to have a somewhat higher energy of formation than MgV, which was predicted to be the thermodynamically most stable Mg defect, followed by substitutional Mg. We note, however, that in the case of ion implantation, the energy for vacancy creation in the sample is provided by the implantation process; hence, the fact that MgV exhibits the lowest defect formation energy may not be the single determining factor which regulates the abundance of complexes formed, and thus, also Mg centers requiring triple or quadruple vacancies might be commonly found. The MgV 2 center was predicted to have a similar configuration to MgV, with an additional vacancy “attached from the side” and a symmetry lowering to C 1 (although no detailed Mg coordinates were published) . From simple geometrical arguments, one might expect the structure of MgV 2 as a central vacancy with two additional nearest-neighbor single vacancies within a (110) plane and hence with the Mg atom displaced along a ⟨100⟩ direction from an S site (Figure S3).…”

Quantum networks based on color centers in diamond

“…78,83,84 In this article, we consider all color centers to be in the negative charge state, except where indicated differently; this negative charge state is the one most commonly studied and used in experiments geared toward entanglement generation. We also note that while other recently investigated color centers in diamond, such as Mg-related defects, 85 show some initial promise for quantum applications, we do not discuss them here due to their early phase of study.…”

Identification and Creation of the Room-Temperature Coherently Controllable ST1 Spin Center in Diamond

“…Defect centers in other materials than diamond such as divacancies and vacancies in SiC, vacancies in hBN, or G-centers in silicon recently attracted a large focus. In diamond, column IV vacancy centers (SiV, GeV, SnV, and PbV) , or the newly discovered MgV , are well-promising systems. Nevertheless, the only defect centers allowing for spin coherent control at room temperature in diamond are the so-called ST1 − and the TR12 , (an intrinsic defect of unknown nature).…”