Single Photon Generation And Detection

Single-photon generation and detection is at the forefront of modern optical physics research. This book is intended to provide a comprehensive overview of the current status of single-photon techniques and research methods in the spectral region from the visible to the infrared. The use of single photons, produced on demand with well-defined quantum properties, offers an unprecedented set of capabilities that are central to the new area of quantum information and are of revolutionary importance in areas that range from the traditional, such as high sensitivity detection for astronomy, remote sensing, and medical diagnostics, to the exotic, such as secretive surveillance and very long communication links for data transmission on interplanetary missions. The goal of this volume is to provide researchers with a comprehensive overview of the technology and techniques that are available to enable them to better design an experimental plan for its intended purpose. The book will be broken into chapters focused specifically on the development and capabilities of the available detectors and sources to allow a comparative understanding to be developed by the reader along with and idea of how the field is progressing and what can be expected in the near future. Along with this technology, we will include chapters devoted to the applications of this technology, which is in fact much of the driver for its development. This is set to become the go-to reference for this field. Covers all the basic aspects needed to perform single-photon experiments and serves as the first reference to any newcomer who would like to produce an experimental design that incorporates the latest techniques Provides a comprehensive overview of the current status of single-photon techniques and research methods in the spectral region from the visible to the infrared, thus giving broad background that should enable newcomers to the field to make rapid progress in gaining proficiency Written by leading experts in the field, among which, the leading Editor is recognized as having laid down the roadmap, thus providing the reader with an authenticated and reliable source

As quantum detectors evolve to become ever more sophisticated, their description in terms of a limited number of generic parameters falls short. An alternative description of the performance of a detector is provided by its positive-operator-valued measure (POVM). In this chapter we introduce a technique, quantum detector tomography, which allows us to experimentally reconstruct the POVM of the detector under test. Detailed examples on how to apply this technique to phase-insensitive detectors are given. We also discuss the challenges for the tomography of phase-sensitive detectors and possible solutions.

In this Chapter, we summarize the current status and future prospects of a number of novel semiconductor-based single-photon detectors, including visible-light photon counters (VLPCs), solid-state photo-multipliers (SSPMs), and quantum-dot-based detectors. SSPMs and VLPCs utilize the gain produced by impact ionization of the impurity band to detect single photons over a wide wavelength range between 0.4 and 28. Quantum-dot-based single-photon detectors use photoconductive gain associated with photogenerated carriers trapped in quantum dots. We cover the basic operating principles of these devices, describe experimental results that demonstrate their unique attributes, present mathematical models that quantify their performance, and discuss the future of these novel detector technologies.

Superconducting materials provide a unique opportunity for single-photon detectors. The combination of the strong non-linearity present in the superconducting-metal transition and in Josephson junctions; the unique electrical property of zero resistance; the fast relaxation processes present in many superconducting materials; and the easily engineered optical absorptance of metals results in a system that can be adapted to many photo-detection requirements. As a result of these material features, a variety of detector families have emerged in recent years based on superconducting nanowires, tunnel junctions, weak thermal links, and kinetic-inductive resonators. The detectors variously provide high speed single-photon detection; high-sensitivity in the infrared, optical, UV, or even x-ray wavelengths; and high efficiency. The resulting applications include quantum and classical high-data-rate communication, biological imaging, LIDAR, and VLSI circuit evaluation among others.

In this chapter we review the process of parametric down-conversion (PDC) and discuss the different methods to use PDC as a heralded single-photon source. PDC is a non-linear optical process, where an incoming pump photon decays, under energy and momentum conservation, into a photon-pair. The creation of photons in pairs allows for the implementation of a single-photon source by detecting one photon (trigger) to herald the presence of its partner (signal). The engineering possibilities of PDC enable the generation of single-photons with high rates in a wide range of frequencies. This chapter is structured as follows: Section 11.2 describes the principles of PDC in non-linear media. We derive the quantum state of the generated photon-pairs, investigate the spectral purity and photon-number purity of the heralded signal photon and discuss the achievable single-photon generation rates. In section 11.3 we turn towards experimental realizations and introduce bulk crystal PDC. Section 11.4 elaborates on the use of periodic poling to engineer the PDC process. Finally, section 11.5 gives an overview over PDC in waveguides. A comparison of experimental data from various heralded singe-photon sources based on PDC is presented in section 11.6 with an overview of nonlinear materials suited for PDC given in section 11.7.

We discuss applying single-photon detectors to measurements with high accuracy. Two primary standard methods of detector calibration are reviewed: one based on a radiant power measurement (substitution method) and the other—on a simultaneous generation of photon pairs (correlation method). It is shown how to apply these methods to two types of detectors: with no photon number resolution (PNR) and with full PNR. In addition, an experimental comparison of the two calibration methods with non-PNR detectors is presented.

To understand the nature of light sources, one needs to know the statistical properties of emitted light and how the tools used to measure those properties reflect those statistics. This chapter will cover the vocabulary and notation necessary for understanding the characteristics of the sources and detectors covered in this book. After a brief review of the quantized electric field and relevant operators, we explore properties of single-photon sources, starting with relationships among state vectors, density matrices and photon number probabilities . Next we investigate properties of , the second-order coherence, and how it relates to . We present an in-depth study of the Hanbury Brown-Twiss interferometer, showing how it can be used to accurately measure in many—but not all—experimental situations. This is followed by a discussion of bunching, antibunching, Poissonian photon statistics, high-order coherences and indistinguishability. The second half of the chapter discusses characteristics of single-photon detectors, starting with the definition of detection efficiency used in this book. We review the POVM (Positive-Operator-Valued-Measure) operators, use them to illustrate the distinction between photon number-resolving (PNR) detectors and click/ no-click detectors, and explore some of the practical limitations of photon number-resolving and energy-resolving detectors. We next discuss the time response of detectors, including timing latency, rise time, timing jitter, dead time, reset time and recovery time. Finally, we cover the distinction between dark count rate and background count rate, and briefly discuss afterpulse probability, active area and operating temperature.