In this paper, we present a comparative analysis of the coherent properties of laser radiation and the birth of the universe, which took place because of quantum fluctuations. Six quantities have been brought under consideration for comparison. They are Entropy, Time, space-time, origin, Temperature, and vacuum fluctuation.

The nature of spontaneous absorption and its technical aspects are discussed. Einstein’s derivation of Planck’s black body energy distribution law has been examined with the inclusion of the process of spontaneous absorption. It has been shown that the inclusion of t he term of spontaneous absorption does not affect the distribution law. Self consistent model of the rate equation approximation justifies the inclusion of process of Spontaneous absorption

All quantum states of light exhibit field fluctuation even in the vacuum state. There are many physical phenomena which result from vacuum fluctuation. The most prominent example is the spontaneous radiation. In quantum optics and laser physics people have succeeded in producing theoretically even a squeezed state of light that fluctuates at a lower noise level than the vacuum fluctuation. The application of squeezed light will provide new opportunities for high precision measurements. In the present work we consider the quantum superposition of state 0 1 01 y =a + b and work out the variances of the quadrature operators 1 ˆX and 2 ˆX . We have shown that for some values of parameters α and β, the quadrature variances become less than the vacuum fluctuation. This indicates the principle of manipulating vacuum.

Quantum interference is a challenging phenomenon in quantum optics. According to this principle of superposition of quantum mechanics, elementary particles such as photon can not only be in more than one place at a given time, but that an individual particle can cross its own trajectory and interfere with the direction of its path. Thomas Young devised the double slit experiment to prove that light consisted of waves. Analysis of the double slit experiment and the interference pattern indicates that each photon not only goes through both the slits simultaneously, but traverses every possible trajectory on the way to the target, not just in theory, but in fact. In the present work we have analysed the situation in terms of quantum superposition and Schrodinger cat states in quantum optics. The nature of photon in this analysis is examined

In the present work we have worked out a vector model for spontaneous emission based on the principle of moving vectors. This simplified approach reflects the work of Weisskopf and Wigner of spontaneous emission