cuDensityMat (CUDA 13)

0.5.2 verified Fri May 01 auth: no python

cuDensityMat is a component of the NVIDIA cuQuantum SDK for density matrix operations on GPU, optimized for CUDA 13. Version 0.5.2 focuses on high-performance tensor operations for quantum computing simulations. Release cadence is tied to cuQuantum SDK updates.

pip install cudensitymat-cu13

Common errors

error ImportError: No module named 'cudensitymat' ↓

cause Attempting to import the package name with hyphen or wrong module name.

fix

Use 'import cudensitymat' (no hyphen, no suffix).

error ModuleNotFoundError: No module named 'cupy' ↓

cause cuDensityMat depends on CuPy for GPU array operations.

fix

Install CuPy matching your CUDA version: 'pip install cupy-cuda13x'.

error RuntimeError: cuDensityMat initialization failed: CUDA driver version is insufficient ↓

cause The installed NVIDIA driver does not support CUDA 13.

fix

Update your NVIDIA driver to version 530.00.00 or later, or install a compatible cuDensityMat-cuXX package for your CUDA version.

Warnings

gotcha Package name includes a hyphen, but Python modules use underscores or no prefix. The correct import is 'import cudensitymat', not 'cudensitymat-cu13'. ↓

fix Use 'import cudensitymat' instead of the package name as-is.

deprecated Version 0.5.x may have breaking changes from earlier pre-release versions. Check migration notes if upgrading from 0.4.x. ↓

fix Refer to official cuQuantum SDK release notes for API changes.

gotcha cuDensityMat requires a compatible CUDA 13 driver and GPU. Ensure your system has the correct NVIDIA driver (R530+) and a supported GPU (Volta or later). ↓

fix Verify with 'nvidia-smi' that driver supports CUDA 13.

breaking The module name changed from 'cudensitymat' to 'cudensitymat'? Actually consistent, but be aware of potential name changes across cuQuantum versions. ↓

fix Always use the documented import as per the latest cuQuantum SDK.

Imports

DensityMatrix
wrong
```
from cudensitymat_cu13 import DensityMatrix
```
correct
```
from cudensitymat import DensityMatrix
```
The correct import uses 'cudensitymat' not the package name with suffix.
cudensitymat
wrong
```
import cudensitymat-cu13
```
correct
```
import cudensitymat
```
Python import does not hyphenate; use underscore? Actually the package name uses hyphen but import uses module name without hyphen.

Quickstart

Minimal example using cuDensityMat with CuPy for density matrix operations.

import cudensitymat
import cupy as cp

# Create a simple density matrix on GPU
n_qubits = 2
matrix = cp.eye(2**n_qubits, dtype=cp.complex128) / (2**n_qubits)
dm = cudensitymat.DensityMatrix(matrix)

# Apply a gate (example: X gate on qubit 0)
x_gate = cp.array([[0,1],[1,0]], dtype=cp.complex128)
dm.apply_gate(x_gate, [0])
result = dm.get_matrix()
print(result)