9.5 Superposition and Interference – review

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Margarita A. Man’ko, Vladimir I. Man’ko

The superposition of pure quantum states explicitly expressed in terms of a nonlinear addition rule of state density operators is reviewed. The probability representation of density matrices of qudit states is used to formulate the interference of the states as a combination of the probability distributions describing pure states. The formalism of quantizer–dequantizer operators is developed. Examples of spin-1/2 states and f-oscillator systems are considered.

Chandrasekhar Roychoudhuri

We model detecting dipoles’ stimulation by multiple waves. Registered fringes (photocurrent variations) are due to the square-modulus operation by the detector; not summation of amplitudes by waves. We review multiple experiments to demonstrate single photon interference is illogical assumption.

Paul Peter Urone, Roger A. Hinrichs

Christopher C. Gerry, P. L. Knight

We describe the properties of a quantum system prepared in superpositions of classically distinguishable states. These states, often called Schrödinger cat states, are of great interest at present. We discuss how they may be realized in quantum optics using nonlinear interactions and cavity quantum electrodynamics. We first describe the quantum properties of field states in a cavity, and demonstrate the interference properties which characterize superposition states and discuss how fragile they are in dissipative environments. Finally, we review current experimental approaches which may realize these states.