Carbon defect qubit in two-dimensional WS2

Abstract

Identifying and fabricating defect qubits in two-dimensional semiconductors are of great interest in exploring candidates for quantum information and sensing applications. A milestone has been recently achieved by demonstrating that single defect, a carbon atom substituting sulphur atom in single layer tungsten disulphide, can be engineered on demand at atomic size level precision, which holds a promise for a scalable and addressable unit. It is an immediate quest to reveal its potential as a qubit. To this end, we determine its electronic structure and optical properties from first principles. We identify the fingerprint of the neutral charge state of the defect in the scanning tunnelling spectrum. In the neutral defect, the giant spin-orbit coupling mixes the singlet and triplet excited states with resulting in phosphorescence at the telecom band that can be used to read out the spin state, and coherent driving with microwave excitation is also viable. Our results establish a scalable qubit in a two-dimensional material with spin-photon interface at the telecom wavelength region.

Hydrothermal synthesis and controlled growth of group-VIB W metal compound nanostructures from tungsten oxide to tungsten disulphide

“…However, it has to pass through the structurally disordered inter-grain boundary, which affect the band structure by creating potential barriers. 65,66 Fig. 7(a i and a ii ) shows the calculated energy band structure, the TDOS and PDOS of the WO 3(5:1) -240 °C primitive-cell.…”

“…However, it has to pass through the structurally disordered inter-grain boundary, which affect the band structure by creating potential barriers. 65,66…”

Non-unique fraction of Fock exchange for defects in two-dimensional materials

“…The same approach has been routinely applied to understand the defect properties in 2D materials [17][18][19][20]. In this Letter, we show that, in contrast to bulk 3D materials, there exists no unique amount of Fock exchange that can reproduce the experimental band gap and satisfying Koopmans' conditions for the defect level concurrently.…”

“…To illustrate this issue, we investigate various point defects in monolayer (ML) WS 2 , including the sulfur monovacancy (V S ), the single cobalt atom substituting sulfur (Co S ) or tungsten (Co W ), and the single carbon atom substituting sulfur (C S ). Several of these defects have recently become the subject of increasing theoretical and experimental efforts following the demonstrated quantum light emitters in 2D transition-metal dichalcogenides (TMDs) [21][22][23][24][25][26], and so are well-motivated for further consideration here [19,[27][28][29].…”

Identification of an Oxygen Defect in Hexagonal Boron Nitride

“…46 We note that understanding the hyperfine interaction is crucial in the decoherence processes 46 and controlling 47 the spin defects in hBN, to realize electron–nuclear entanglement acting as quantum memory and quantum register. 48 − 53 Unfortunately, very few EPR spectra have been reported in hBN with often non-conclusive origin (see ref ( 3 ) and references therein). Very recently, a novel EPR center has been observed with a very characteristic hyperfine pattern, 54 which provides a hope for unambiguous identification of a defect in hBN, as recently demonstrated for the V B defect in hBN.…”