Quantum mechanics promises a much more powerful information-processing technology than is possible using classical physics. Photons offer one potentially important platform for encoding and manipulating information using the rules of quantum physics. In order to realize this potential, they must interact with each other, something that they are not normally inclined to do. However, as discussed in the Perspective by
Walmsley and Raymer, it is possible using a combination of standard optical elements and detectors to synthesize an effective interaction provided all the photons used have identical properties. An important direction of current research is to develop sources of identical photons.
Quantum mechanics promises a much more powerful information-processing technology than is possible using classical physics. Photons offer one potentially important platform for encoding and manipulating information using the rules of quantum physics. In order to realize this potential, they must interact with each other, something that they are not normally inclined to do. However, as discussed in the Perspective by
Walmsley and Raymer, it is possible using a combination of standard optical elements and detectors to synthesize an effective interaction provided all the photons used have identical properties. An important direction of current research is to develop sources of identical photons.
Quantum physics has deeply changed the scientific perception of reality. The physical realization of quantum states is a vast resource for humankind: it can be used for a surprisingly large manifold of purposes; among those, the generation of truly random numbers, the possibility of distributing a shared private key for cryptography, or new ways to perform computation. Today, the most practical approach of creating and manipulating quantum states relies on playing with photons, i.e. light. Indeed most of quantum information processing experiments are accomplished via optical means. This situation is the consequence of the extraordinary development of photonic tools over the last decades, in terms of sources (lasers, quantum dots...), processing (optical fibers, filters, multiplexers, crystals, waveguides...), and detectors (photodiodes, superconducting nanowires, transition edge sensors...). "In this manuscript we present some (modest) contributions to the field, done during a PhD in the group of applied physics at University of Geneva (Switzerland)".
Efficient single-photon detectors have enabled new directions in experimental physics. Superconducting nanowire single-photon detectors (SNSPDs) are a vital component in loophole-free Bell inequality violation, metrology beyond the shot-noise limit, and nuclear clock transition sensing. We discuss recent progress in cryogenic silicon photonic platforms at the National Institute of Standards and Technology (NIST). These platforms co-integrate SNSPDs, silicon-on-insulator waveguides, superconducting amplifiers, and all-silicon light sources based on emissive crystal defect centers. Together, these elements lay a foundation for large-scale quantum information systems and extremely low-power neuromorphic architectures. Neuromorphic photonics uses the complementary properties of optics and electronics to realize information processing capabilities far beyond what is possible with pure electronics. Its performance potentials are highly desired as neural network approaches have retaken the helm of machine learning. We present recent results in neuromorphic photonic architectures at NIST and Princeton: one signaling at single-photon levels, one signaling on sub-nanosecond timescales, both propelled by the emerging industrialization of silicon photonics. Neuromorphic and quantum processing approaches based on silicon photonics will overlap substantially in terms of technical challenges and enabling technologies.
Information processing with light is ubiquitous, from communication, metrology and imaging to computing. When we consider light as a quantum mechanical object, new ways of information processing become possible. In this review I give an overview of how quantum information processing can be implemented with single photons, and what hurdles still need to be overcome to implement the various applications in practice. I will place special emphasis on the quantum mechanical properties of light that make it different from classical light, and how these properties relate to quantum information processing tasks.
Photonics is an effective platform for engineering quantum states of many photons that can be harnessed for applications in information processing tasks, ranging from secure communications to enhanced sensors to efficient simulation of physical or other systems. I will discuss recent developments and some challenges to achieving this promise. Building and measuring multi-photon quantum states suitable for these applications demands a means for them to interfere and for detection at the level of individual photons. Photonic integrated circuits are well suited to these tasks at a scale that is not possible by other means. Advances in the design and utilization of circuits and detectors enable quantum advantage, and indeed provide new opportunities for classical optical systems.
Integrated photonics provides a powerful approach for developing compact, stable and scalable architectures for the generation, manipulation and detection of quantum states of light. To this end, several material platforms are being developed in parallel, each providing its specific assets, and hybridization techniques to combine their strengths are now possible. This review focuses on AlGaAs, a III-V semiconductor platform combining a mature fabrication technology, direct band-gap compliant with electrical injection, low-loss operation, large electro-optic effect, and compatibility with superconducting detectors for on-chip detection. We detail recent implementations of room-temperature sources of quantum light based on the high second- and third-order optical nonlinearities of the material, as well as photonic circuits embedding various functionalities ranging from polarizing beamsplitters to Mach-Zehnder interferometers, modulators and tunable filters. We then present several realizations of quantum state engineering enabled by these recent advances and discuss open perspectives and remaining challenges in the field of integrated quantum photonics with AlGaAs.
Information processing with light is ubiquitous, from communication, metrology and imaging to computing. When we consider light as a quantum mechanical object, new ways of information processing become possible. In this review I give an overview of how quantum information processing can be implemented with single photons, and what hurdles still need to be overcome to implement the various applications in practice. I will place special emphasis on the quantum mechanical properties of light that make it different from classical light, and how these properties relate to quantum information processing tasks.