expval

Method of Operator.

Overloads

Name	Description
expval(const State rhs) -> complex	Computes the expectation value of an Operator for a given state. Calculates <$\psi$|O|$\psi$>, where $\psi$ is a quantum state and $O$ is an operator.
expval(const RealMatrix rhs) -> real	Computes the expectation value of an Operator in a given real state. Calculates <$\psi$|O|$\psi$>, where $\psi$ is a state vector and $O$ is an operator.
expval(const ComplexMatrix rhs) -> complex	Computes the expectation value of an Operator in a given complex state. Calculates <$\psi$|O|$\psi$>.

expval(const State rhs) -> complex

Computes the expectation value of an Operator for a given state. Calculates <$\psi$|O|$\psi$>, where $\psi$ is a quantum state and $O$ is an operator.

Parameters

• rhs: The state ($\psi$) in which the expectation value is computed.

Returns

The (complex) expectation value of the operator in the state.

Example

                    var state = Qbit("000101")
                    var value = expval(X(0), state) // Compute <state|X(0)|state>
                    

expval(const RealMatrix rhs) -> real

Computes the expectation value of an Operator in a given real state. Calculates <$\psi$|O|$\psi$>, where $\psi$ is a state vector and $O$ is an operator.

Parameters

• rhs: The real state vector ($\psi$) in which the expectation value is computed.

Returns

The real expectation value of the operator in the state.

Example

var state = vector([4], as_real) // Create a real state vector, $\psi$ 
var value = expval(X(0), state)  // Compute <state|X(0)|state>

expval(const ComplexMatrix rhs) -> complex

Computes the expectation value of an Operator in a given complex state. Calculates <$\psi$|O|$\psi$>.

Parameters

• rhs: The complex state vector in which the expectation value is computed.

Returns

The complex expectation value of the operator in the state.

Example

var state = vector([4])          // Create a complex state vector
var value = expval(X(0), state)  // Compute <state|X(0)|state>