PROBABILISTIC THEORIES: WHAT IS SPECIAL ABOUT QUANTUM MECHANICS?
PROBABILISTIC THEORIES: WHAT IS SPECIAL ABOUT QUANTUM MECHANICS?
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概率理论:量子力学有什么特别之处?
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发表时间:
2009
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通讯作者:
G. Mauro
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作者:
G. Mauro
Quantum Mechanics (QM) is a very special probabilistic theory, yet we don't know which operational principles make it so. All axiomatization attempts suffer at least one postulate of a mathematical nature. Here I will analyze the possibility of deriving QM as the mathematical representation of a fair operational framework, i.e. a set of rules which allows the experimenter to make predictions on future events on the basis of suitable tests, e.g. without interference from uncontrollable sources. Two postulates need to be satisfied by any fair operational framework: NSF: no-signaling from the future—for the possibility of making predictions on the basis of past tests; PFAITH: ex- istence of a preparationally faithful state—for the possibility of preparing any state and calibrating any test. I will show that all theories satisfying NSF ad- mit a C ∗ -algebra representation of events as linear transformations of effects. Based on a very general notion of dynamical independence, it is easy to see that all such probabilistic theories are non-signaling without interaction (non- signaling for short)—another requirement for a fair operational framework. Postulate PFAITH then implies the local observability principle, the tensor- product structure for the linear spaces of states and effects, the impossibility of bit commitment and additional features, such an operational definition of transpose, a scalar product for effects, weak-selfduality of the theory, and more. Dual to Postulate PFAITH an analogous postulate for effects would give additional quantum features, such as teleportation. However, all possible consequences of these postulates still need to be investigated, and it is not clear yet if we can derive QM from the present postulates only. What is special about QM is that also effects make a C ∗ -algebra. More precisely, this is true for all hybrid quantum-classical theories, corresponding to QM plus super-selection rules. However, whereas the sum of effects can be operationally defined, the notion of effect abhors any kind of composition. Based on the natural postulate of atomicity of evolution (AE) one can de- fine composition of effects by identifying them with atomic events through the Choi-Jamiolkowski isomorphism (CJ). In this way the quantum-classical hy- brid is selected within the large arena of non-signaling probabilistic theories, including the Popescu-Rohrlich boxes. The CJ isomorphism looks natural in an operational context, and it is hoped that it will soon be converted into an operational principle.