Accession Number : AD0443719


Title :   QUANTUM DESCRIPTIONS ON COMMUNICATION THEORY,


Corporate Author : STANFORD UNIV CA STANFORD ELECTRONICS LABS


Personal Author(s) : She, Chiao-Yao


Report Date : May 1964


Pagination or Media Count : 99


Abstract : This work is an analytical investigation of the significance of quantum mechanical effects on the channel capacity of a communication system. Unlike previous approaches, this analysis adopts a realistic physical model of a communication system composed of a driven transmitting antenna and a distant narrow band receiving cavity and treats the problem in fully quantum mechanical terms. One of the results of the work is the determination of the state of a quantum system after a simultaneous measurement of noncommuting observables is made with maximum accuracy allowed by the uncertainty principle of quantum mechanics. We find the system is left in a minimum uncertainty state whose wave function is the familiar Gaussian wave packet. This state is an eigenstate of a certain complex operator. Statistical interpretation for the repeated measurements on the electromagnetic field is formulated through the simultaneous measurement. A second result arises when the theory of simultaneous measurement is applied to the communication system just described. It is found that each of the repeated measurements introduces one quantum of noise energy into the receiving cavity at the moment the measurement is performed. The noise at any one time is made up of the appropriately attenuated noise quanta introduced by each of the previous measurements. (Author)


Descriptors :   *INFORMATION THEORY , QUANTUM THEORY , OSCILLATORS , HARMONIC GENERATORS , PROBABILITY , FUNCTIONS(MATHEMATICS) , BANDWIDTH , STATISTICAL ANALYSIS , MEASUREMENT


Distribution Statement : APPROVED FOR PUBLIC RELEASE