Room-temperature coherent manipulation of single-spin qubits in silicon carbide with a high readout contrast

Abstract

Spin defects in silicon carbide (SiC) with mature wafer-scale fabrication and micro/nano-processing technologies have recently drawn considerable attention. Although room temperature single-spin manipulation of colour centres in SiC has been demonstrated, the typically detected contrast is less than 2$\%$, and the photon count rate is also low. Here, we present the coherent manipulation of single divacancy spins in 4H-SiC with a high readout contrast ($-30\%$) and a high photon count rate (150 kilo counts per second) under ambient conditions, which are competitive with the nitrogen-vacancy (NV) centres in diamond. Coupling between a single defect spin and a nearby nuclear spin is also observed. We further provide a theoretical explanation for the high readout contrast by analysing the defect levels and decay paths. Since the high readout contrast is of utmost importance in many applications of quantum technologies, this work might open a new territory for SiC-based quantum devices with many advanced properties of the host material.

Experimental Determination of the Dipole Orientation of Single Color Centers in Silicon Carbide

“…We use a high-purity 4H-SiC epitaxy sample under room temperature that has been controllably fabricated arrays of single defects in it by carbon ion (C + ) implantation and annealing . We use a nonresonant continuous wave (CW) laser of 914 nm to excite single defects.…”

“…Compared with the PL1–4 divacancy centers, The PL6 centers have a high saturated count rate (about 150-kilo counts per second). The PL5 and PL6 centers also have a high ODMR readout contrast (approximating 30%) at room temperature . Those properties are comparable to the NV centers in diamond and are essential for many quantum applications. , Besides, the PL5 and PL6 centers possess the charge stability resisting to photoionization effect. , …”

“…Spin defects in silicon carbide gradually have become promising candidates for quantum applications such as quantum communication, , quantum computation, − quantum sensing, − and some kinds of quantum devices, , which rely on excellent spin and optical properties themselves, and the large-scale single crystal growth and mature nanofabrication technics of the host material. Divacancy defects − in 4H-SiC are among the most attractive color centers, properties of which are similar to those of the nitrogen-vacancy (NV) centers in the diamond. Because of the hexagonal crystal structure of 4H-SiC, four identified types of divacancy centers exist, namely hh (PL1), kk (PL2), hk (PL3), and kh (PL4), and there also exists the PL5 and PL6 centers whose properties are similar to the identified divacancy. , The PL1 defect spins can be coherently controlled at room temperature, but the PL2 and PL4 defect spins have no detectable optically detected magnetic resonance (ODMR) signals at room temperature .…”

“…Because of the hexagonal crystal structure of 4H-SiC, four identified types of divacancy centers exist, namely hh (PL1), kk (PL2), hk (PL3), and kh (PL4), and there also exists the PL5 and PL6 centers whose properties are similar to the identified divacancy. , The PL1 defect spins can be coherently controlled at room temperature, but the PL2 and PL4 defect spins have no detectable optically detected magnetic resonance (ODMR) signals at room temperature . Although the PL3 centers have ODMR signals at room temperature, , a single PL3 center was not found in the 4H-SiC samples generated via electron radiation or carbon ion implantation. ,, The PL5 and PL6 centers in 4H-SiC have been recently assigned to divacancy configurations inside stacking faults that act as local quantum wells in 4H-SiC, making the PL5 and PL6 centers process advanced properties . Compared with the PL1–4 divacancy centers, The PL6 centers have a high saturated count rate (about 150-kilo counts per second).…”

Coherent dynamics of multi-spin $\rm V_B^-$ centers in hexagonal boron nitride

“…Among this family of layered materials, hBN has a large bandgap of ∼6 eV, which makes it have the ability to host plenty of kinds of defects, just similar to diamond [29][30][31] and silicon carbide [32][33][34], etc. Singlelayer hBN was first found to emit single photons at room temperature in 2016 by Tran et al [15], and after that, a great of interest was stimulated to treat hBN defects as the promising single-photon emitters [16][17][18][19][20][21][22][23][24][25], and fur-thermore, as the potential solid spin qubit [35][36][37][38][39][40][41][42][43].…”