Qiskit C API Enables End-to-End Quantum + HPC Workflows with New Demo

Summary: Qiskit C API Facilitates Hybrid Quantum-Classical Computing

IBM Quantum has released the Qiskit C API, a significant advancement enabling the integration of quantum computing with traditional high-performance computing (HPC) workflows. This new interface, detailed in Qiskit v2.2, allows developers to build end-to-end quantum-centric supercomputing (QCSC) applications using compiled languages like C++ and Fortran, paving the way for demonstrating quantum advantage. A new demo, built upon this API, provides a practical example of this capability.

Key Highlights:

• Qiskit C API Introduction: The Qiskit C API is the first compiled language interface within the Qiskit framework. This is a crucial step toward realizing the full potential of QCSC.
• Qiskit v2.2 Release: The release includes a dedicated transpiler function for quantum circuits, enabling the construction of complete QCSC applications.
• HPC-Ready SQD Addon: A new SQD (selected basis diagonalization) addon, written in C++, is designed for efficient execution on HPC systems. It leverages MPI and OpenMP for parallel processing.
• Demo Workflow: The demo demonstrates a real QCSC workflow using the SQD algorithm to approximate the ground state energy of Fe₄S₄, a molecular cluster.
• Integration with Existing Tools: The C API demo integrates with various projects, including Qiskit C++, QRMI (Quantum Resource Management Interface), SBD (selected basis diagonalization) eigensolver, and qiskit-addon-sqd-hpc.

Detailed Explanation:

1. The Significance of the Qiskit C API

The Qiskit C API addresses a critical gap in quantum computing development. Previously, developers were limited to scripting languages like Python for building quantum algorithms. The C API unlocks the ability to integrate quantum computations seamlessly into existing HPC codebases, written in languages like C++ and Fortran, which are prevalent in scientific computing.

• Nature: A compiled language interface for Qiskit.
• Purpose: To enable the creation of end-to-end quantum-centric supercomputing workflows within HPC environments.
• Impact: Facilitates the adoption of quantum computing by researchers and developers already familiar with HPC languages and tools.

2. Core Components of the Qiskit C API Demo

The demo leverages several key components to showcase the capabilities of the C API:

• Qiskit C API: The fundamental interface for building quantum applications in C++.
• HPC-Ready SQD Addon: A C++17 library for performing selected basis diagonalization, optimized for HPC environments.
  • C++17: Chosen for its balance of modernity and broad compiler support.
  • MPI and OpenMP: Enables parallel execution across multiple processors and nodes.
  • Platform Support: Tested on Linux, macOS (x86_64 and ARMv8), and Windows (x86_64).
  • Performance: Includes a micro-benchmark suite for performance evaluation.
• QRMI (Quantum Resource Management Interface): Provides a C++ interface to IBM Quantum hardware.
• SBD (selected basis diagonalization) eigensolver: A RIKEN-developed eigensolver integrated into the workflow.
• qiskit-addon-sqd-hpc: The HPC-ready SQD addon, specifically designed for parallel execution.

3. Running the Demo

The provided instructions detail the steps to build and run the Qiskit C API demo.

• Prerequisites: Rust v1.85+, a C++17 compiler, CMake, Make, OpenBLAS, OpenMPI, and Eigen3.
• Build Process: Involves building the Qiskit C extension, the QRMI service, and the demo itself using make.
• IBM Quantum Integration: Requires setting environment variables with your IBM Quantum API token and instance.
• Execution: The demo can be run with various command-line options to control the simulation parameters, such as the number of samples, the number of iterations, and the backend.

4. Future Directions and Contributions

IBM Quantum encourages developers to explore the demo and contribute to the open-source projects it integrates. This includes contributing to Qiskit C++, QRMI, the SBD eigensolver, and qiskit-addon-sqd-hpc.

Conclusion

The introduction of the Qiskit C API and the accompanying demo represent a significant step towards bridging the gap between quantum computing and traditional HPC. This enables a broader range of researchers and developers to leverage the power of quantum computation for solving complex problems in various fields. The development of such tools and the contributions to open-source projects are crucial for realizing the promise of quantum advantage.

Reference: https://www.ibm.com/quantum/blog/c-api-enables-end-to-end-hpc-demo