CQC and Q-CTRL Develop Extensions to IBM’s Qiskit that Provide Further Improvements

There were announcements this week from both Cambridge Quantum Computing (CQC) and Q-CTRL that show how these two software companies can beat IBM at its own game and provide software for IBM’s Q hardware that improves upon IBM’s own implementations in Qiskit.

In a paper this week titled “Exploring molecular excited states with CQC using IBM’s Qiskit”, CQC describes how they were able to develop a circuit to simulate the lithium hydride (LiH) molecule. A key point in the paper is a comparison of how the transpiler within CQC’s t|ket> software provides a much better optimization than the default transpiler within IBM’s Qiskit Terra module. A transpiler is the software that takes a programmer level quantum circuit and maps it to a circuit that is compatible with the native gates and architecture of the actual quantum hardware to reduce circuit size, depth, and other circuit resources. This makes programs faster and reduces the impact of noise on measurement results.

CQC provided the following table in their paper that compares the results for their LiH simulation program. The target quantum computer was IBM’s 16 Qubit Melbourne machine and their table shows a >50% improvement with CQC’s software.

Molecule: LiH Total Gates Overall Depth Overall CNOT Count
Qiskit default routing 42178 23367 17977
t|ket> circuit optimization + routing 19256 10022 8711

In another announcement this week, Q-CTRL unveiled a new product called Open Controls. Open Controls is a Python package designed to help users deploy quantum control techniques to suppress errors in their quantum hardware. Open Controls can potentially be run on any quantum machine, but it is also designed to complement IBM’s Qiskit Ignis framework for characterizing, verifying, and mitigating noise in quantum circuits and devices. Q-CTRL operates at a different level than CQC’s software mentioned above because it focusses on implementing better modulation techniques of the individual gates and qubits to improve gate fidelity and extend the coherence time of a qubit. For more information on Open Controls you can view Q-CTRL’s press release here, the Open Control product page here, and the GitHub page here.