Hi All - My name is Dan Sandberg and I am studying physical chemistry at the Univ. of Connecticut in the USA. I recently heard a talk on quantum computing and, at the time, began to picture a quantum computer which employed a photoactive protein. I decided to attempt to see this idea to fruition and present it to the department. However I can not seem to get a strong grasp on the intricacies of the quantum computer and I am stumbling with some of the jargon. I was hoping someone could assist me with answering some perhaps basic questions. For example, In 1993, Seth Lloyn, Prof. of quantum mechanical engineering at MIT, published a paper on "A Potentially Realizable Quantum Computer". In this paper he states, "the only logical operations that necessarily require dissipation are irreversible ones". What does he mean by "dissipation"?