paddle_quantum.biocomputing.operators

various indicators used to build the protein Hamiltonian

paddle_quantum.biocomputing.operators.edge_direction_indicator(edge, affected_qubits=None, direction=None)

Calculate the direction indicate operator for a given edge at given affected qubits.

\begin{array}{r} I_{0} (e) = (1 - q_{0}) (1 - q_{1}) \\ I_{1} (e) = (1 - q_{0}) q_{1} \\ I_{2} (e) = q_{0} (1 - q_{1}) \\ I_{3} (e) = q_{0} q_{1} \\ s a t i s f i e s \sum_{k} I_{k} (e) == 1 \end{array}

Parameters:

edge (Tuple[int]) – Edge index in protein’s directed graph.
affected_qubits (List[int] | None) – The indices of qubits used to encode the indicator.
direction (int | None) – Direction of edge in the diamond lattice, valid values 0, 1, 2, 3.

Returns:

A tuple contains the sign and indicator operator corresponds to that edge.

Return type:

Tuple[float, Dict]

paddle_quantum.biocomputing.operators.contact_indicator(qindex)

The indicator which indicates whether two nodes in the protein are contact.

q i n d e x = c o n t a c t o r_{s} t a r t + i n d e x_{o} f_{c} o n t a c t_{p} a i r

Parameters:: qindex (int) – index of qubit used as indicator of whether two nodes in the protein chain contact.
Returns:: Contact indicator in QubitOperator form.
Return type:: QubitOperator

paddle_quantum.biocomputing.operators.backwalk_indicator(e0_attrs, e1_attrs)

Indicator of whether two consecutive bonds in protein overlap.

\sum_{a = 0}^{3} I_{a} (e_{i}) I_{a} (e_{i + 1})

Parameters:

Returns:

Backwalk indicator in QubitOperator form.

Return type:

QubitOperator