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| What Is Quantum Information? |
| 2006-08-22
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Speaker : Prof. Robert B. Griffiths Physics Department,Carnegie-Mellon University,Pittsburgh, PA 15213, USA
Date : 2006-08-22 16:00
Venue :
Conference Hall 322, ITP/理论物理所322报告厅
Abstract : Despite much work on quantum information in recent years, there is#@no generally accepted definition of what it is all about, and how it differs#@from or relates to classical information theory as developed by Shannon in the context of classical probabilities. Since consistent quantum probabilities require the use of different incompatible frameworks (families of histories),this suggests that quantum information comes in many different incompatible types or "species"; e.g., those associated with different components of spin#@angular momentum of a spin-half particle. Classical information theory can be applied to each separate quantum species when considered by itself, and#@"classical information" is just a particular species of quantum information in a context in which no other type is of practical interest. Relating information belonging to different incompatible species requires a new theory based on quantum mechanics, and developing it is the central task of quantum#@information theory. The talk will illustrate how this approach can be applied in the case of teleportation, where it helps us understand why two "classical" bits are needed to carry out the protocol, and to decoherence, where a particular#@("pointer basis") type of information about a system present at some place#@in its environment suppresses other ("coherent") types of information at other places, including the system itself at a later time.#@
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