Single photons and individual quantum systems are at the heart of recent developments in quantum technologies and are about to enable a variety of novel applications in sensing, communication, and computing. Photonic devices are the key to control interactions between quantum systems and light as well as to simultaneously engineer the properties of photons. For scalable quantum technologies, the employed quantum systems are solid-state based, thus placing the field of quantum photonics at the intersection of physics, nanotechnology, and material sciences. This special issue features 14 contributions and addresses recent advances in several material platforms.
Single photons and individual quantum systems are at the heart of recent developments in quantum technologies and are about to enable a variety of novel applications in sensing, communication, and computing. Photonic devices are the key to control interactions between quantum systems and light as well as to simultaneously engineer the properties of photons. For scalable quantum technologies, the employed quantum systems are solid-state based, thus placing the field of quantum photonics at the intersection of physics, nanotechnology, and material sciences. This special issue features 14 contributions and addresses recent advances in several material platforms.
The emerging field of quantum nanophotonics offers potential chip-scale integration of multi-functional quantum processing infrastructures. The key technological challenges lie on new material design and integration with quantum emitters. It is of fundamental importance in developing hybrid material platforms and experimental approaches to address a wide array of challenging issues that cannot be easily overcome with conventional quantum optics approaches. This special issue features 10 contributions that address various aspects of emerging quantum photonic platforms, devices and approaches that combine the advantages of several material systems to realize chip-scale quantum information processing in an efficient and robust manner.
The ability to control the state of individual atoms is a new challenge for science and technology in the 21st century. Currently, experiments on individual quantum systems such as trapped ions, single molecules, quantum dots, superconducting qubits and photons are crucial for the rapidly growing field of quantum information processing and communication. In general, solid state systems are preferable for scaling and the choice of material plays a crucial role; for example, in classical electronic devices continual performance enhancement and miniaturization is strongly linked to the success of silicon-based technology. For quantum applications, diamond has the potential to become the material of choice, because its large bandgap enables the control of optically active impurities and higher operation temperature. This focus issue collates original research contributions from some of the leading groups in the field as a showcase for the very latest developments in diamond-based quantum technologies.
Photons are very promising resources for the whole field of quantum information processing. Bulk optics are currently not suitable for the realization of complex quantum optical schemes due to several drawbacks. The ongoing miniaturization of photonic structures due to the availability of sophisticated nanofabrication has provided huge opportunities for physical research of novel phenomena in nanophotonic systems and quantum technological applications. These include quantum information processing such as quantum computing, quantum communication, quantum metrology, and quantum sensing. Quantum communication is already quite advanced with several quantum key distribution (QKD) systems commercially available offering absolute security. Photonic quantum technologies are enabling breakthroughs in experimental tests of quantum physics and are close to practical applications of quantum technologies in imaging, secure communications, ultrasensitive metrology and quantum computing. There are several advantages to encoding a quantum bit onto a photon: the preparation and manipulation of single photons is easy, and the photonic qubit is a natural candidate for quantum imaging and communications. Furthermore, the qubit can be encoded in various degrees of freedom such as on the position, phase, time-bin, energy, angular momentum, polarization of the photon—or a combination of these. This flexibility leads to enormous opportunities for scientific exploration and in practical applications. This special issue on “Photonic Quantum Technologies” presents selected papers on photonic quantum systems from leading groups in the world. The articles represent a flavor of the cutting-edge research that is going on in this area. The studied material systems range from molecules to semiconductor quantum emitters. A major challenge is the design of telecom photon emitters with high efficiency, good yield, spectral purity, stability and the possibility of mass manufacture. We believe that this Special Issue will provide an overview of recent exciting developments in the field of photonic quantum technologies, serving to keep researchers up-to-date with the latest progress and spurring on new concepts in this field.
The field of quantum sensing leverages quantum mechanical resources such as superposition, entanglement, and squeezing to surpass classical limits in measurement precision and enable new sensing modalities. This Special Topic Collection in Applied Physics Reviews brings together recent advances spanning theory, materials, device engineering, and applications of quantum sensors. Contributions cover a wide range of platforms, including atomic, solid-state, optomechanics, and photonics, highlighting both fundamental science and emerging technologies. The collection illustrates the transition of quantum sensing from foundational concepts toward scalable technologies and broadens its impact across physics, engineering, and applied sciences.
In recent years, the field of quantum nanophotonics has been thriving with an intense interest in the development of new theories, devices, and applications for specific uses.This special issue on "Quantum nanophotonics" highlights some recent developments in this topic through reviews, perspectives, and research papers.This issue contains review and perspective articles that provide a comprehensive overview of cutting-edge topics.Chang and Zwiller [1] review the recent progresses in integrated quantum photonics using nanowires, focusing on integrated emitters, detectors, and fabrication methods.This review also presents the applications for quantum information processing and sensing based on nanowires.Gali [2] summarizes the ab initio theory to fully understand solid-state qubits, which are an essential component in the quantum photonic device.This computational method has been applied to the calculation of excited states, photo-ionization threshold, optical excitation spectra, effective mass states, and spin dynamics.This approach could give insights beyond conventional density functional theory that cannot fully capture the characteristics of excited states.Biotechnologies are being used in a variety of quantum optics and photonics or vice versa.DNA nanotechnology, using the information of DNA to design and manufacture artificial nucleic acid structures for technological uses, has been utilized in the field of quantum emitters.Exotic traits of DNA enable the grabbing of quantum emitters and steering of their directors at the molecular level of resolution.The relevant studies were extensively reviewed by Cho et al. [3].Reversely, the understanding of light-matter interaction in quantum optics provides a hint to investigate chemical and biological processes.Kim et al. [4] present a review of plexcitonic and vibro-polaritonic strong coupling based on light-matter interaction with optical resonators.The authors introduce from fundamentals of strong coupling, configuration and characteristics of plexcitons, and applications for chemistry and biological detection.Kim et al. [5] discuss that nanophotonic resonance engineering can make the near-unity readout fidelity necessary for improving the sensitivity of NV quantum sensing.The perspective gives insight into the background of NV quantum sensing, applications of resonant structures, and the remaining challenges for practical sensing.Zheng and Kim [6] address the degradation mechanisms of perovskite-based light-emitting diodes.The degradation can potentially occur in external and internal processes, leading to distinct effects on performance and stability.Various research articles on quantum nanophotonics are included.There is growing interest in optimizing the single photon emitter (SPE) that can be integrated into the photonic circuit and enable practical application.Azzam et al. [7] demonstrate the Purcell enhancement of WSe 2 SPE using a dielectric cavity.The dielectric cavity imposes an oriented strain profile on the WSe 2 , which can make the polarization state of the SPE selectively controlled.Xu et al. [8] report a high-purity SPE based on nanodiamonds (NDs) with negatively charged silicon vacancy (SiV -) centers using an ion implantation method.They successfully prevent SiV -emitters from
Quantum emitters serve as essential on-demand photonic resources, generating quantum states of light such as single photons and entangled photon pairs while serving as interfaces between light and matter. Buried in the solid state, quantum emitters enable a straightforward adoption of advanced nanofabrication techniques, facilitating precise engineering of their photonic environment for scalable quantum technologies. In this review, we introduce the fundamentals of quantum emitters and the key metrics characterising their performance. We highlight three material platforms: quantum dots, defect centres in diamond, and defect centres in silicon carbide. We summarise the recent developments of these platforms and discuss their advancements in quantum applications, including quantum communication, computation, and sensing. Finally, we provide a comparison across the three platforms, along with an outlook on future directions and potential challenges.