Quantum entanglement

Friday 06/11/2009 14:30

Quantum entanglement and the addition and subtraction of a photon presented by Myungshik Kim from Queen’s University, Belfast

One of the most striking formulas we learn during the undergraduate quantum mechanics course is the commutation relation, [a, a+] = 1. For a light field, this means that photon annihilation after creation is different from photon creation after annihilation and the difference is equal to the unity. The non-commutativity is closely related to the uncertainty principle in quantum mechanics; the precise measurement of two non-commutative observables simultaneously is impossible. Even though the bosonic commutation relation is taught in every quantum mechanics course, the direct and ‘exact’ proof seemed to be experimentally unreachable. In this talk, the verification of the bosonic commutation relation is discussed using single photon interference.

Prof Kim will demonstrate a scheme based on single-photon interference for transferring the microscopic quantum behaviour to macroscopic classical objects (as in Schrödinger’s cat paradox) by realising arbitrary superpositions of distinct quantum operations. Applying them to a classical light field the commutation relation to be verified directly. The Belfast group’s results may be interesting because, in addition to clear demonstration of the fundamental textbook concept in quantum mechanics, the possibility of implementing general operator superpositions is an alternative promising tool to control and engineer quantum information for future technologies.

Programme online

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