<!--HTML-->Variational algorithms are among the most promising near-term applications of quantum computers. Their execution is particularly challenging for current quantum computing systems since they require a tight interaction between the host CPU and the quantum accelerator. Here we present Intel Quantum SDK, an LLVM-based C++ compiler toolchain to efficiently compile and execute variational algorithms. Using our extension to the C++ language, the user can write programs describing both the quantum and classical parts of the algorithm. The classical and quantum parts of the C++ source are then compiled by the LLVM framework and by a novel quantum device compiler component, respectively. The runtime is augmented with the capability of executing quantum circuits dynamically, meaning that the values of the circuit's parameters can be changed without triggering the recompilation of the quantum part. We briefly describe how to gain access to the Intel Quantum SDK and get started with hybrid quantum-classical workloads.
<!--HTML-->Variational algorithms are among the most promising near-term applications of quantum computers. Their execution is particularly challenging for current quantum computing systems since they require a tight interaction between the host CPU and the quantum accelerator. Here we present Intel Quantum SDK, an LLVM-based C++ compiler toolchain to efficiently compile and execute variational algorithms. Using our extension to the C++ language, the user can write programs describing both the quantum and classical parts of the algorithm. The classical and quantum parts of the C++ source are then compiled by the LLVM framework and by a novel quantum device compiler component, respectively. The runtime is augmented with the capability of executing quantum circuits dynamically, meaning that the values of the circuit's parameters can be changed without triggering the recompilation of the quantum part. We briefly describe how to gain access to the Intel Quantum SDK and get started with hybrid quantum-classical workloads.
Variational algorithms are a representative class of quantum computing workloads that combine quantum and classical computing. This paper presents an LLVM-based C++ compiler toolchain to efficiently execute variational hybrid quantum-classical algorithms on a computational system in which the quantum device acts as an accelerator. We introduce a set of extensions to the C++ language for programming these algorithms. We define a novel Executable and Linking Format (ELF) for Quantum and create a quantum device compiler component in the LLVM framework to compile the quantum part of the C++ source and reuse the host compiler in the LLVM framework to compile the classical computing part of the C++ source. A variational algorithm runs a quantum circuit repeatedly, each time with different gate parameters. We add to the quantum runtime the capability to execute dynamically a quantum circuit with different parameters. Thus, programmers can call quantum routines the same way as classical routines. With these capabilities, a variational hybrid quantum-classical algorithm can be specified in a single-source code and only needs to be compiled once for all iterations. The single compilation significantly reduces the execution latency of variational algorithms. We evaluate the framework's performance by running quantum circuits that prepare Thermofield Double (TFD) states, a quantum-classical variational algorithm.
The Intel(R) Quantum Software Development Kit (SDK) offers a comprehensive platform for developers to create quantum applications using an LLVM-based compiler with user-friendly C++ language extensions. This full-stack solution facilitates the expression and optimization of quantum circuits and includes a quantum runtime library for seamless hybrid execution between classical and quantum kernels. The runtime enables dynamic parameter determination for quantum circuits, allowing both quantum and classical components of variational algorithms to be defined within a single program, compiled once, and significantly reducing execution latency. The SDK features a suite of quantum simulators, including simulations of Intel's quantum hardware components such as qubit control processors, control electronics, and quantum dot qubits. With a unified interface, the Intel Quantum SDK allows users to target ideal qubit simulators, realistic Intel quantum hardware simulators, and future Intel quantum hardware, enabling efficient optimization, compilation, and execution of scalable hybrid quantum-classical variational algorithms.
To address the growing needs for scalable High Performance Computing (HPC) and Quantum Computing (QC) integration, we present our HPC-QC full stack framework and its hybrid workload development capability with modular hardware/device-agnostic software integration approach. The latest development in extensible interfaces for quantum programming, dispatching, and compilation within existing mature HPC programming environment are demonstrated. Our HPC-QC full stack enables high-level, portable invocation of quantum kernels from commercial quantum SDKs within HPC meta-program in compiled languages (C/C++ and Fortran) as well as Python through a quantum programming interface library extension. An adaptive circuit knitting hypervisor is being developed to partition large quantum circuits into sub-circuits that fit on smaller noisy quantum devices and classical simulators. At the lower-level, we leverage Cray LLVM-based compilation framework to transform and consume LLVM IR and Quantum IR (QIR) from commercial quantum software frontends in a retargetable fashion to different hardware architectures. Several hybrid HPC-QC multi-node multi-CPU and GPU workloads (including solving linear system of equations, quantum optimization, and simulating quantum phase transitions) have been demonstrated on HPE EX supercomputers to illustrate functionality and execution viability for all three components developed so far. This work provides the framework for a unified quantum-classical programming environment built upon classical HPC software stack (compilers, libraries, parallel runtime and process scheduling).
Near term quantum devices have the potential to outperform classical computing through the use of hybrid classical-quantum algorithms such as Variational Quantum Eigensolvers. These iterative algorithms use a classical optimiser to update a parameterised quantum circuit. Each iteration, the circuit is executed on a physical quantum processor or quantum computing simulator, and the average measurement result is passed back to the classical optimiser. When many iterations are required, the whole quantum program is also recompiled many times. We have implemented explicit parameters that prevent recompilation of the whole program in the quantum programming framework OpenQL, called OpenQLPC. These parameters improve the compilation and therefore total runtime for hybrid quantum-classical algorithms. We compare the time required for compilation and simulation of the MAXCUT algorithm in OpenQLpcto the same algorithm in both PyQuil and Qiskit. We show that efficient handling of parameterised circuits results in up to 70 % reduction in total compilation time for the MAXCUT benchmark, and leads to a reduced total execution time. When using OpenQLPC, compilation of hybrid algorithms is up to two times faster than when using PyQuil or Qiskit.
The rapid development of quantum computing technology has led to an increasing need for efficient and accessible programming tools that can bridge the gap between classical and quantum computing paradigms. In this paper, we introduce the Intel®Quantum SDK, a powerful software development kit designed to facilitate hybrid quantum-classical programming using the C++ Quantum Extension. The SDK provides a comprehensive set of tools and libraries that enable developers to harness the power of quantum computing while leveraging their existing knowledge of classical programming techniques. By incorporating quantum algorithms and operations within a familiar C++ framework, the Intel Quantum SDK empowers programmers to create innovative hybrid applications that can tackle complex problems and drive advancements in various fields, including cryptography, optimization, and materials science. This paper will guide readers through the essential concepts, features, and capabilities of the Intel Quantum SDK. This seamless integration of quantum and classical programming paradigms paves the way for the development of innovative and efficient solutions to complex computational challenges, ultimately driving the advancement of quantum computing technology and its real-world applications.
To address the urgent need in the NISQ era for high-performance, scalable quantum compilers and to advance the integration of classical and quantum computing, we present QLLVM, an advanced Quantum-Classical co-compilation framework built on LLVM. To our knowledge, QLLVM delivers an end-to-end, LLVM-based compilation workflow that unifies the build of classical high-performance programs, including CUDA, MPI, and C++, together with quantum programs into a single executable. For quantum program compilation, QLLVM adopts a three-stage design: high-level optimizations are implemented in the MLIR Quantum dialect and then lowered to QIR, an LLVM IR-based representation, for low-level optimization and hardware mapping. Its extensible architecture and seamless interoperability with classical high-performance computing provide an efficient, flexible, industrial-grade compilation infrastructure for future quantum software development. Experimental results show that, on the MQTBench benchmark suite, QLLVM reduces circuit depth and gate counts compared with state-of-the-art compilers and demonstrates clear advantages in compiling hybrid classical-quantum programs.