RESUMO
Quantum emitters in solid-state crystals have recently attracted a great deal of attention due to their simple applicability in optical quantum technologies. The polarization of single photons generated by quantum emitters is one of the key parameters that plays a crucial role in various applications, such as quantum computation, which uses the indistinguishability of photons. However, the degree of single-photon polarization is typically quantified using the time-averaged photoluminescence intensity of single emitters, which provides limited information about the dipole properties in solids. In this work, we use single defects in hexagonal boron nitride and nanodiamond as efficient room-temperature single-photon sources to reveal the origin and temporal evolution of the dipole orientation in solid-state quantum emitters. The angles of the excitation and emission dipoles relative to the crystal axes were determined experimentally and then calculated using density functional theory, which resulted in characteristic angles for every specific defect that can be used as an efficient tool for defect identification and understanding their atomic structure. Moreover, the temporal polarization dynamics revealed a strongly modified linear polarization visibility that depends on the excited-state decay time of the individual excitation. This effect can potentially be traced back to the excitation of excess charges in the local crystal environment. Understanding such hidden time-dependent mechanisms can further improve the performance of polarization-sensitive experiments, particularly that for quantum communication with single-photon emitters.
RESUMO
A solid-state quantum emitter is a crucial component for optical quantum technologies, ideally with a compatible wavelength for efficient coupling to other components in a quantum network. It is essential to understand fluorescent defects that lead to specific emitters. In this Letter, we employ density functional theory (DFT) to demonstrate the calculations of the complete optical fingerprints of quantum emitters in hexagonal boron nitride. Our results suggest that instead of comparing a single optical property, like the zero-phonon line energy, multiple properties should be used when comparing simulations to the experiment. Moreover, we apply this approach to predict the suitability of using the emitters in specific quantum applications. We therefore apply DFT calculations to identify quantum emitters with a lower risk of misassignments and a way to design optical quantum systems. Hence, we provide a recipe for classification and generation of universal quantum emitters in future hybrid quantum networks.
RESUMO
Optical quantum technologies promise to revolutionize today's information processing and sensors. Crucial to many quantum applications are efficient sources of pure single photons. For a quantum emitter to be used in such application, or for different quantum systems to be coupled to each other, the optical emission wavelength of the quantum emitter needs to be tailored. Here, we use density functional theory to calculate and manipulate the transition energy of fluorescent defects in the two-dimensional material hexagonal boron nitride. Our calculations feature the HSE06 functional which allows us to accurately predict the electronic band structures of 267 different defects. Moreover, using strain-tuning we can tailor the optical transition energy of suitable quantum emitters to match precisely that of quantum technology applications. We therefore not only provide a guide to make emitters for a specific application, but also have a promising pathway of tailoring quantum emitters that can couple to other solid-state qubit systems such as color centers in diamond.
