Pure Python bindings for the pure C++11/OpenCL Qrack quantum computer simulator library
(PyQrack is just pure Qrack.)
Note, if building from source: You must build and install unitaryfund/qrack to build the main branch from source. CI/CD builds wheels that contain pre-compiled Qrack binaries, and that is the form published on PyPi. You must also install OpenCL.
Performance can benefit greatly from following the Qrack repository "Quick Start" and "Power user considerations."
If you use an integrated graphics accelerator, like the Intel HD, setting environment variable PYQRACK_HOST_POINTER_DEFAULT_ON=1 (or to any "truthy" value) will automatically set the default of isHostPointer option of QrackSimulator to True, to engage "zero-copy" mode by default.
Import and instantiate QrackSimulator instances. This simulator can perform arbitrary single qubit and controlled-single-qubit gates, as well as other specific gates like SWAP.
Any 2x2 bit operator matrix is represented by a list of 4 complex floating point numbers, in row-major order.
Single and array "b" parameters represent Pauli operator bases. They are specified according to the enumeration of the Pauli class.
MC[x] and MAC[x] methods are controlled single bit gates, with as many control qubits as you specify via Python list c argument. MCX is multiply-controlled Pauli X, and MACX is "anti-"controlled Pauli X, i.e. "anti-control" activates the gate if all control bits are specifically off, as opposed to on.
To load the required unitaryfund/qrack libraries from a different location, set the PYQRACK_SHARED_LIB_PATH environment variable.
PyQrack has experimental support for PyZX Circuit definitions as an intermediate representation for QrackSimulator. To try this, load a Circuit in PyZX, (use that module to optimize your circuit, as you like,) and create a QrackSimulator() instance using the pyzxCircuit named argument of the constructor, like so:
sim = QrackSimulator(pyzxCircuit=c)where c is a PyZX circuit object. The circuit will automatically be simulated in the constructed QrackSimulator instance. This also allows loading from QASM and other intermediate representations supported by PyZX.
See https://pyqrack.readthedocs.io/en/latest/ for an API reference.
For custom Qrack build floating-point precision, where options are half, float, double, and quad, set an environment variable via export QRACK_FPPOW=[n] (or as appropriate to your shell) where [n] is the logarithm base 2 of the number of bits in the systemic floating point type (4, 5, 6, or 7, with 5 or float as default, i.e. 2**5=32 for 32-bit float). Your Qrack installation floating-point build option must match this specific value, which might require a custom Qrack build.
Please feel welcome to open an issue, if you'd like help. 😃
Special thanks go to Zeeshan Ahmed, for bug fixes and design suggestions, Ashish Panigrahi, for documentation and design suggestions, WingCode, for documentation, and to the broader community of Qrack contributors, for years of happy Qracking! You rock!