🏆 QuEST

The Quantum Exact Simulation Toolkit is a high performance simulator of quantum circuits, state-vectors and density matrices. QuEST uses multithreading, GPU acceleration and distribution to run lightning first on laptops, desktops and networked supercomputers. QuEST just works; it is stand-alone, requires no installation, and is trivial to compile and run. QuEST hybridises OpenMP and MPI with huge compiler support to run on all sorts of multicore, multi-CPU and distributed hardware, uses HIP to run on AMD GPUs, integrates cuQuantum and Thrust for cutting-edge performance on modern NVIDIA GPUs, and has a custom kernel backend to run on older CUDA-compatible GPUs. And it hides these deployment modes behind a single, seamless interface.

Open bounties:

• $25 | Implement RAM probe
• $50 | Extend Pauli rotations to accept complex angles
• $50 | Improve applyCompMatr accuracy with compensated summation
• $100 | Improve the accuracy of Trotterisation with randomisation and commuting groups
• $125 | Implement SWAP fusion
• $150 | Optimise calcExpecPauliStrSum() by batch-processing similar PauliStr