Symbols of Multiqubit States Admitting a Physical Interpretation*

详细

We study the multiqubit states and the corresponding minimal sets of dequantizers and quantizers, such that symbols of the operators (observables) obtained with the help of the dequantizers admit a physical interpretation; more precisely, the symbols can be measured in the experiments. We consider two types of such quantities: (i) the probabilities of spin projections onto certain directions and (ii) the mean values of these projections. We provide an explicit description of the systems of dequantizers and quantizers for both types of these quantities corresponding to N-qubit states. We show that, in view of such symbols, it is possible to represent the density matrices of the N-qubit states in the form of series expansion in terms of quantizers with the coefficients as measurable observables.