  Peculiarities of multiqubit measurement are for the most part similar to
peculiarities of measurement for qudit -- quantum object with
finite-dimensional Hilbert space. Three different interpretations of
measurement concept are analysed. One of those is purely quantum and is in
collection, for a given state of the object to be measured, of incompatible
observable measurement results in amount enough for reconstruction of the
state. Two others make evident the difference between the reduced density
matrix and the density matrices of physical objects involved in the
measurement. It is shown that the von Neumann projectors produce an idea of a
phase portrait of qudit state as a set of mathematical expectations for
projectors on the possible pure states. The phase portrait includes probability
distributions for all the resolutions of identity of the qudit observable
algebra. The phase portrait of a composite system comprised by a qudit pair
generates local and conditional phase portraits of particles. The entanglement
is represented by the dependence of the shape of conditional phase portrait on
the properties of the observable used in the measurement for the other
particle. Analysis of the properties of a conditional phase portrait of a
multiqubit qubits shows that absence of the entanglement is possible only in
the case of substantial restrictions imposed on the method of multiqubit
decomposition into qubits.
