Two-dimensional (2D) materials have emerged as promising candidates for next-generation integrated single-photon emitters (SPEs). However, significant variability in the emission energies presents a major challenge in producing identical single photons from different 2D SPEs, which may become crucial for practical quantum applications. Although various approaches to dynamically tuning the emission energies of 2D SPEs have been developed to address the issue, the practical solution to matching multiple individual 2D SPEs is still scarce. In this work, we demonstrate precise emission energy tuning of individual SPEs in a WSe2 monolayer. Our approach utilizes localized strain fields near individual SPEs, which we control by adjusting the volume of a stressor layer through laser annealing. This technique allows continuous emission energy tuning of up to 15 meV while maintaining the qualities of SPEs. Additionally, we showcase the precise spectral alignment of three distinct SPEs in a single WSe2 monolayer to the same wavelength.

Complementary metal-oxide-semiconductor (CMOS)-compatible photonic integrated circuits (PICs) capable of operating at visible wavelengths are critical for advanced quantum systems, including trapped-ion quantum computers. However, standard silicon (Si) PICs are fundamentally unsuitable for this task due to silicon's strong intrinsic material absorption, which prevents the efficient propagation of visible light in Si waveguides. In this work, we present a hybrid two-dimensional (2D) integrated silicon-on-insulator (SOI) PIC platform that enables out-of-plane visible light emission through second-harmonic generation (SHG). This emission arises from a monolayer tungsten diselenide (WSe2) with broken inversion symmetry, which is encapsulated within hexagonal boron nitride (hBN) to avoid degradation. Our approach bypasses Si absorption by leveraging the transparency of Si waveguides at the infrared pump wavelength, while nonlinear frequency conversion occurs exclusively in the 2D material at the out-coupling interface to convert the infrared photons into visible light. This work opens a promising pathway toward realizing CMOS-compatible, on-chip visible light sources for quantum technologies.

Forming single-photon emitters (SPEs) in insulating hexagonal boron nitride (hBN) has sparked wide interests in the quantum photonics. Despite significant progress, it remains challenging to deterministically create SPEs at precise locations with a specific type of element for creating defects. In this study, we present a straightforward approach to generate site-deterministic carbon-functionalized quantum emitters in hBN by harnessing ultrasonic nanoindentation. The obtained SPEs are high-quality and can be scaled up to large arrays in a single fabrication step. Comprehensive experimental analyses reveal that the insertion of carbon atoms into the hBN lattice is the source of the robust quantum emission. Complementary theoretical studies suggest possible candidates for the structural origin of the defects based on our experimental results. This rapid and scalable nanoindentation method provides a new way to create SPE arrays with specific types of atoms, enabling the comprehensive investigation of the origins and mechanics of SPE formations in two-dimensional (2D) materials and beyond.

Single-photon emitters (SPEs) hold the key to many quantum technologies including quantum computing. In particular, developing a scalable array of identical SPEs can play an important role in preparing single photons - crucial resources for computation - at a high rate, allowing to improve the computational capacity. Recently, different types of SPEs have been found in various 2D materials. Towards realizing scalable SPE arrays in 2D materials for quantum computation, it is required to develop tunable SPEs that can produce identical photons by precisely controlling emission properties. Here, we present a brief review of the recent progress on various tuning methods in different 2D materials. Firstly, we discuss the operation principle of different 2D SPEs along with their unique characteristics. Secondly, we introduce various dynamic strain engineering methods for tuning the emission wavelengths in 2D SPEs. We also present several electric field-induced wavelength tuning methods for 2D SPEs. Lastly, we discuss the outlook of dynamically tunable 2D SPEs towards scalable 2D SPE arrays for realizing practical quantum photonics applications.

We present a strain engineering platform that allows the dynamic tuning of the emission wavelength of a monolayer WSe2. A large and localized strain was induced in monolayer 2D materials by patterning a photoresist layer with internal stress into two elliptical shapes with a finite gap in between, which is referred to as a dimer in this work. By applying laser annealing on the dimer stressor while monitoring the exciton emission, we demonstrate the capability to dynamically tune the emission wavelength of the bright exciton in the monolayer WSe2.

The photonics-based approach has recently become a strong candidate for realising a large-scale, practical quantum processor. Particularly in recent years, two-dimensional (2D) materials have become a strong candidate for developing an ideal integrated light source owing to their several unique advantages such as convenient on-chip integration. In this work, we study the effect of strain on the emission wavelength and carrier lifetime. We first show that the geometry of stressors can adjust the amount of strain and emission wavelength. Using this strain engineering technique, we demonstrate that the emission wavelength can be significantly shifted by ~10 nm while the carrier lifetime can also be engineered by ~30 %.

We report broadband ultrafast photoluminescence from graphene ranging from visible to telecom wavelengths. We show strongly modified emission spectra owing to the presence of the cavity effect and demonstrate improved thermal stability enabled by hBN.

Ultrafast light emission from monolayer graphene shows attractive potential for developing integrated light sources for next-generation graphene-based electronic-photonic integrated circuits. In particular, graphene light sources operating at the telecom wavelengths are highly desired for the implementation of graphene-based ultrahigh-speed optical communication. Currently, most of the studies on ultrafast light emission from graphene have been performed in the visible spectrum, while studies on ultrafast emission at the telecom wavelengths remain scarce. Here, we present experimental observations of strong ultrafast thermal emission at telecom wavelengths from wafer-scale monolayer graphene. Our results show that the emission spectra can be strongly modified by the presence of the cavity effect to produce an enhanced emission at telecom wavelengths. We corroborate our experimental results with simulations and show that by designing a suitable cavity thickness, one can easily tune the emission profile from visible to telecom wavelength regardless of the pump power. In addition, we demonstrate that the insertion of a monolayer of hexagonal boron nitride between graphene and the substrate helps improve the thermal stability of graphene, thereby providing more than five times enhancement of the ultrafast thermal emission. Our results provide a potential solution for stable on-chip nanoscale light sources with ultrahigh speed modulation.

Two-dimensional (2D) materials-based photodetectors in the infrared range hold the key to enabling a wide range of optoelectronics applications including infrared imaging and optical communications. While there exist 2D materials with a narrow bandgap sensitive to infrared photons, a two-photon absorption (TPA) process can also enable infrared photodetection in well-established 2D materials with large bandgaps such as WSe2 and MoS2. However, most of the TPA photodetectors suffer from low responsivity, preventing this method from being widely adopted for infrared photodetection. Herein, we experimentally demonstrate 2D materials-based TPA avalanche photodiodes achieving an ultrahigh responsivity. The WSe2/MoS2 heterostructure absorbs infrared photons with an energy smaller than the material bandgaps via a low-efficiency TPA process. The significant avalanche effect with a gain of ∼1300 improves the responsivity, resulting in the record-high responsivity of 88 μA/W. We believe that this work paves the way toward building practical and high-efficiency 2D materials-based infrared photodetectors.