willie84 / qiskitnullgatetranspilerpass Goto Github PK

Abstract
Qisikit transpiler is known to reduce redundancy in a quantum circuit without changing the intended circuit behavior. Qiskit transpiler uses a transpiler manager to manages various passes. The Qiskit transpiler passes documentation can be found here https://qiskit.org/documentation/apidoc/transpiler/passes/passes.html

Looking at the transpiler passes moreso gates optimizations passes; only CxCancellation pass that has been implemented. But the question is what if some other gates are canceling each other? Some gates, under certain conditions, have no effect on the qubits they are applied to. Gates that are grouped with their inverses, have a null control or act on the operations’ eigenstates with eigenvalue 1, belong to this class. This idea is derived from this paper:
https://arxiv.org/pdf/1110.2998.pdf under the rule of Null gates

Description
To do so we will need to implement some logical look through where we can eliminate gates that are inverse of each other under ceratin conditions. Since a circuit in a transpiler is represented with a DAG; the project will need to create conditions and look through the DAG to eliminate null operations in a linear sequence of the gates. For example:

Look at the above-described paper Figure 6 and see some null operations.

Members

Willie Macharia([email protected])
Deliverable
A transpiler pass