CUDA-Q Guide

CUDA-Q Guide

Purpose

Guide users through CUDA-Q installation, basic kernels, GPU simulation targets, QPU access, built-in applications, multi-GPU execution, and Python @cudaq.kernel authoring. For Qiskit-to-CUDA-Q ports, route to the cudaq-importing skill instead.

Prerequisites

• Python 3.10+ for Python CUDA-Q workflows.
• CUDA Toolkit and an NVIDIA GPU for GPU-accelerated targets on Linux.
• CPU-only simulation is available through qpp-cpu; macOS is CPU-only.
• C++ workflows require Linux or WSL and C++20.
• QPU workflows require provider-specific credentials and accounts.

Instructions

• Invoke with /cudaq-guide [argument].
• If no argument is given, display the onboarding menu and ask which topic the user wants.
• Use the routing table below to choose the relevant reference file.
• Read local CUDA-Q documentation files when the answer depends on a specific CUDA-Q version or backend behavior.
• Do not answer Qiskit porting questions from this skill; use cudaq-importing.

Routing by Argument

Menu

CUDA-Q Getting Started
CUDA-Q is NVIDIA's unified quantum-classical programming model for CPUs, GPUs, and QPUs.Supports Python and C++. Docs: https://nvidia.github.io/cuda-quantum/latest/
Choose a topic:  /cudaq-guide install         Install CUDA-Q  /cudaq-guide test-program    Write and run a Bell-state kernel  /cudaq-guide gpu-sim         Accelerate simulation on NVIDIA GPUs  /cudaq-guide qpu             Connect to real QPU hardware  /cudaq-guide applications    Explore what you can build  /cudaq-guide parallelize     Run across GPUs or QPUs  /cudaq-guide author          Author @cudaq.kernel Python code

Reference Files

• references/onboarding.md [blocked]: installation, test program, GPU targets, QPU providers, application areas, parallelization modes, examples, and platform troubleshooting.
• references/authoring.md [blocked]: execution APIs, kernel-language constraints, silent-failure pitfalls, recurring coding patterns, resource metrics, debugging, and validation.

Limitations

• Guidance targets CUDA-Q Python/C++ workflows, with authoring details focused on decorator-mode Python APIs used in CUDA-Q 0.14 and 0.15.
• GPU and multi-GPU support depends on local CUDA-Q, CUDA Toolkit, driver, MPI, and hardware availability.
• QPU access and target options are provider-specific and may change; verify against local docs before giving operational steps.

Troubleshooting

• Import error after pip install cudaq: check Python 3.10+ and supported OS.
• No GPU detected: verify CUDA Toolkit and nvidia-smi; fall back to qpp-cpu.
• Kernel compile error: read references/authoring.md [blocked] and check the restricted kernel-language subset.
• Version-specific behavior differs: compare cudaq.__version__ with the latest documentation, then review relevant documentation or source changes when debugging an installed version that is not the latest release.
• QPU submission fails: verify provider credentials are set as environment variables or through a secrets manager, never hardcoded.
• Documentation lookup fails: retry transient MCP or repository lookup once, then fall back to local docs or official CUDA-Q documentation.