A key goal of research into quantum information processing is the development of technologies that are scaleable in complexity while allowing the mass manufacture of devices that promise transformative effects on information science. The demonstration that integrated photonics circuits could be made to perform operations that exploit the quantum nature of the photon has turned them into leading candidates for practical quantum information processing technologies. To fully achieve their promise, however, requires research from diverse fields. This focus issue provides a snapshot of some of the areas in which key advances have been made. We are grateful for the contributions from leading teams based around the globe and hope that the degree of progress being made in a challenging and exciting field is apparent from the papers published here.
A key goal of research into quantum information processing is the development of technologies that are scaleable in complexity while allowing the mass manufacture of devices that promise transformative effects on information science. The demonstration that integrated photonics circuits could be made to perform operations that exploit the quantum nature of the photon has turned them into leading candidates for practical quantum information processing technologies. To fully achieve their promise, however, requires research from diverse fields. This focus issue provides a snapshot of some of the areas in which key advances have been made. We are grateful for the contributions from leading teams based around the globe and hope that the degree of progress being made in a challenging and exciting field is apparent from the papers published here.
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.
Photons have been a flagship system for studying quantum mechanics, advancing quantum information science, and developing quantum technologies. Quantum entanglement, teleportation, quantum key distribution, and early quantum computing demonstrations were pioneered in this technology because photons represent a naturally mobile and low-noise system with quantum-limited detection readily available. The quantum states of individual photons can be manipulated with very high precision using interferometry, an experimental staple that has been under continuous development since the 19th century. The complexity of photonic quantum computing devices and protocol realizations has raced ahead as both underlying technologies and theoretical schemes have continued to develop. Today, photonic quantum computing represents an exciting path to medium- and large-scale processing. It promises to put aside its reputation for requiring excessive resource overheads due to inefficient two-qubit gates. Instead, the ability to generate large numbers of photons—and the development of integrated platforms, improved sources and detectors, novel noise-tolerant theoretical approaches, and more—have solidified it as a leading contender for both quantum information processing and quantum networking. Our concise review provides a flyover of some key aspects of the field, with a focus on experiment. Apart from being a short and accessible introduction, its many references to in-depth articles and longer specialist reviews serve as a launching point for deeper study of the field.
Quantum technologies promise a change of paradigm for many fields of application, for example in communication systems, in high-performance computing and simulation of quantum systems, as well as in sensor technology. However, the experimental realization of suitable system still poses considerable challenges. Current efforts in photonic quantum science target the implementation of practical devices and scalable systems, where the realization of quantum devices and controlled quantum network structures is key for envisioned future technologies. Here we present our progress on the engineering of integrated photonic systems, which can overcome current limitations for the realization of scalable photonic systems. Specifically, our research currently focuses on three different but complementary topics: integrated devices based on lithium niobate circuits, engineering and harnessing the temporal-spectral structure of quantum states of light, and photonic quantum computation.
The realization of scalable, real world devices in quantum technologies requires myriad new approaches and hardware components. Integrated photonics play a crucial role in many applications in quantum information and quantum sensing, enabling the realization of key components such as new light sources, waveguides, resonators, and detectors. The field of integrated quantum photonics is booming, and an increasing number of research groups are contributing to the accelerating efforts to study fundamental and technological challenges at the intersection of quantum optics, nanophotonics, and hybrid integrated devices. This Special Topic Collection is dedicated to highlighting important progress in the field of integrated quantum photonics and presenting new cutting-edge results, both experimental and theoretical, toward the common goal of exploring quantum photonic phenomena.
It would be difficult to overestimate the level of attention being paid worldwide to quantum information processing, and anticipated advantages it may offer to a wide variety of pursuits in engineering, technology, and basic science. Futurists muse on the wondrous possibilities and theorists formulate actual algorithms for advanced computing not possible with classical computing machines, if only there were scalable quantum computers. Further, several groups have performed compelling experiments related to quantum teleportation and quantum key distribution – both essential pieces for quantum cryptography. Still, it is a very challenging hardware problem to design architectures that support, appropriately protect, route, and process qubits to function as universal logic gates. To date, most of the optical successes toward this goal have been in bulk media, which is not easily scalable to carry out the required degree quantum error correction. In this talk, I will discuss a couple of the proposals that my collaborators at the Air Force Research Laboratory, at the Rochester Institute of Technology, and I have made toward addressing the issue, among others, of scalability. Further, thanks to the inception of the AIM Photonics Initiative, I will talk briefly about experimental tests that we have started and others that we have planned for assessing in situ the effectiveness of the devices that we have analyzed theoretically.
The purpose of this issue is to highlight the recent progress and trends in the development of novel nano- and quantum photonic technologies. The articles published in this issue cover a broad range of areas, including: 1) novel nanophotonic light sources-both classical (lasers) and nonclassical (single- and entangled photon sources); 2) nonlinear optics in nanophotonic structures; 3) quantum optics and quantum information processing based on nanophotonics platform; 4) efficient devices for optical interconnects and optical information processing based on novel nanophotonic structures. This issue contains 25 papers, including eight invited, authored by well-established research groups and promising scientists from all over the world. The invited articles include extended reviews on entangled photon generation using silicon nanowire waveguides; cavity quantum electrodynamics and lasing oscillation in single quantum dot photonic crystal nanocavity systems; quantum plasmonic circuits; theoretical analysis of few-photon single-atom cavity quantum electrodynamics; semiconductor quantum dot micropillar microcavities for quantum optics in solid state; nanofiber-based optical trapping of cold neutral atoms; switching and counting with atomic vapors in photonic-crystal fibers; and production of multiple diamondbased single-photon sources. The contributed articles cover a broad variety of key nanophotonics and quantum photonics research areas, including recently obtained results on bright single-photon emission from a quantum dot in a circular Bragg grating microcavity, supercontinuum generation in nanostructured silicon waveguides, electrically driven photonic crystal nanocavity devices, and silicon quantum dots.