Martin J. Stevens
Published: 2013-11-29
Total Pages: 63
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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.