MatrQ Interface

This is a ‘type interface.’ See Type Interfaces for more info on what that is.

Declares types for dealing with quantum states and POVMs of a fixed dimension which we'll call here dim. See also Tomographer::MatrQ.

typedef ... RealScalar

The real scalar type we're working with.

typedef ... ComplexScalar

The complex scalar type we're working with.

typedef ... IntFreqType

The integral type to use for measurement counts. Usually int is enough, except if in your experiment you take >1e9 measurements

typedef ... MatrixType

The type needed to represent a density matrix. This is usually expected to be a Eigen type.

int dim() const

The dimension of the quantum system. Return any integer type, usually std::size_t. Inline of course is better.

int dim2() const

The squared dimension of the quantum system. Return any integer type, usually std::size_t. Inline of course is better.

int ndof() const

The squared dimension of the quantum system, minus one. This is the number of degrees of freedom of the density matrix. Return any integer type, usually std::size_t. Inline of course is better.

MatrixType initMatrixType() const

Returns an expression which can be assigned to a MatrixType such that the matrix is initialized to a square dim x dim zero matrix.

typedef ... VectorParamType

The type needed to represent a X-parameterization of a density matrix. This is usually expected to be a Eigen type.

MatrixType initVectorParamType() const

Returns an expression which can be assigned to a VectorParamType such that the vector is initialized to a zero column vector with dim*dim entries.

typedef ... VectorParamNdofType

The type needed to represent some parameterization of a density matrix with dim*dim-1 parameters. This is usually expected to be a Eigen type.

MatrixType initVectorParamNdofType() const

Returns an expression which can be assigned to a VectorParamNdofType such that the vector is initialized to a zero column vector with dim*dim-1 entries.

typedef ... VectorParamListType

The type needed to represent a list of X-parameterizations of e.g. POVM effects, each with dim*dim parameters. This is usually expected to be a Eigen type.

MatrixType initVectorParamListType(std::size_t length) const

Returns an expression which can be assigned to a VectorParamListType such that the list is initialized to a list with length copies of a zero column vector with dim*dim entries.

typedef ... FreqListType

The type needed to represent frequency counts of measurements. This is typically an Eigen::Array integral type.

MatrixType initFreqListType(std::size_t len) const

Returns an expression which can be assigned to a FreqListType such that the vector is initialized to len items with zero counts each.