Some Questions in Quantum Optics

Gerd Leuchs

This short course aims at giving an introduction to quantum optics using phenomenological approaches and visualizing the field from the viewpoint of a practitioner. There are altogether five parts: (1)pointing out a close link between Maxwell's equations and the properties of the quantum vacuum with its virtual particle anti-particle pairs [1], [2]; (2)introduction to field quantization from an experimental perspective using the intuition of a classical optical scientist; (3)answering the question “What does it mean if optics is quantum? What distinguishes quantum from classical? [3], [5] (4)description of quantum optical experiments with discrete and with continuous variables with special emphasis on Wigner functions in phase space and the special role of the quantum measurement process [4]; (5)In this fifth part we address the question: “Is hard core quantum optics solely concerned with the study of fundamental physics questions or is it also useful for practical applications? From laser interferometric gravitational wave detection to quantum distribution of cryptographic keys and quantum information processing [6]–[8].

Vladimir B. Braginsky

Z. Ficek, Mohamed Ridza Wahiddin

In this chapter, we will address one of the basic questions in quantum optics: How do we find an unknown state of the electromagnetic (EM) field, or in general, how do we find quantum state of a given system? The question is essentially about what are detectors and how an external field, that wewant to detect, interacts with them. We may also see how the formulation of problems in quantum optics depends on the detection schemes.

H. J. Carmichael, Roy J. Glauber, Marlan O. Scully

Bruno M. Escher, R. L. de Matos Filho, L. Davidovich

An open question in optical interferometry is what is the fundamental quantum limit in the presence of photon losses. This question is addressed in the present paper, by finding an analytical lower bound for the uncertainty in the phase shift estimation, which implies, for any state of light, and even for arbitrarily small losses, that this uncertainty scales asymptotically with the number of photons at best as the shot noise.

H. J. Carmichael, Roy J. Glauber, Marlan O. Scully