ENTANGLEMENT, NON- LOCALITY AND QUANTUM COMPUTATION

Prof. Sandu Popescu, University of Bristol on 17 May 2004

The chairman, Vioctor Suchar, introduced Prof. Popescu as one of the leading scientists in the field.
Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated. This leads to correlations between observable physical properties of the systems that are stronger than any classical correlations. As a result, measurements performed on one system may be interpreted as "influencing" other systems entangled with it.

Though an an area of active research, some of the essential properties of entanglement are now understood, and it is the basis for emerging technologies such as quantum computing and quantum cryptography.(1) In ordinary ("classical") computing the basis is the binary digit or "bit" which can have a value of either 0 or 1. In quantum computing, bits are replaced with the " qubits" which are in entangled states - partially 0 and partially 1 which allow calculations to be done in parallel. Measuring the value of a qubit , causes it to collapse into the two classical bits, 0 or 1, and it influences the state of other qubits entangled with it.
The speaker used a number of examples to illustrate the basic concepts, and noted that quantum computation is in its very early stages. Quantum computing is a cutting edge application of quantum mechanics, and no one can forecast at this point how along it may take to develop a useable technology.
This highly interesting lecture ended a series of seven meetings on the concepts, interpretation and applications of modern physics that started in April 2003.
Victor Suchar

(1) Wikipedia. Web: http://en.wikipedia.org