diff --git a/benchmarks/pauli_operations.py b/benchmarks/pauli_operations.py new file mode 100644 index 0000000..fcb9bd5 --- /dev/null +++ b/benchmarks/pauli_operations.py @@ -0,0 +1,153 @@ +import numpy as np +from dataclasses import dataclass + + +@dataclass +class PauliString: + string: str + weight: float = 1.0 + +@dataclass +class SparseMatrix: + rows: np.ndarray + columns: np.ndarray + values: np.ndarray + +@dataclass +class SparsePauliString: + columns: np.ndarray + values: np.ndarray + weight: float = 1.0 + + +class PauliComposer: + def __init__(self, pauli: PauliString) -> None: + self.pauli = pauli + self.n_qubits = len(pauli.string) + self.n_vals = 1 << self.n_qubits + self.n_ys = pauli.string.count("Y") + + + def __resolve_init_conditions(self) -> None: + first_col = 0 + for p in self.pauli.string: + first_col <<= 1 + if p == "X" or p == "Y": + first_col += 1 + + match self.n_ys % 4: + case 0: + first_val = 1.0 + case 1: + first_val = -1.0j + case 2: + first_val = -1.0 + case 3: + first_val = 1.0j + + return first_col, first_val + + + def sparse_pauli(self) -> SparsePauliString: + cols = np.empty(self.n_vals, dtype=np.int32) + vals = np.empty(self.n_vals, dtype=np.complex128) + cols[0], vals[0] = self.__resolve_init_conditions() + + for l in range(self.n_qubits): + p = self.pauli.string[self.n_qubits - l - 1] + pow_of_two = 1 << l + + new_slice = slice(pow_of_two, 2*pow_of_two) + old_slice = slice(0, pow_of_two) + + match p: + case "I": + cols[new_slice] = cols[old_slice] + pow_of_two + vals[new_slice] = vals[old_slice] + case "X": + cols[new_slice] = cols[old_slice] - pow_of_two + vals[new_slice] = vals[old_slice] + case "Y": + cols[new_slice] = cols[old_slice] - pow_of_two + vals[new_slice] = -vals[old_slice] + case "Z": + cols[new_slice] = cols[old_slice] + pow_of_two + vals[new_slice] = -vals[old_slice] + + return SparsePauliString(weight=self.pauli.weight, columns=cols, values=vals) + + + def sparse_diag_pauli(self) -> SparsePauliString: + assert self.pauli.string.count("X") + self.pauli.string.count("Y") == 0 + + cols = np.arange(self.n_vals, dtype=np.int32) + vals = np.ones(self.n_vals, dtype=np.complex128) + + for l in range(self.n_qubits): + p = self.pauli.string[self.n_qubits - l - 1] + pow_of_two = 1 << l + + new_slice = slice(pow_of_two, 2*pow_of_two) + old_slice = slice(0, pow_of_two) + + match p: + case "I": + vals[new_slice] = vals[old_slice] + case "Z": + vals[new_slice] = -vals[old_slice] + + return SparsePauliString(weight=self.pauli.weight, columns=cols, values=vals) + + + def efficient_sparse_multiply(self, state: np.ndarray) -> np.ndarray: + assert state.ndim == 2 + + cols = np.empty(self.n_vals, dtype=np.int32) + vals = np.empty(self.n_vals, dtype=np.complex128) + cols[0], vals[0] = self.__resolve_init_conditions() + + product = np.empty((self.n_vals, state.shape[1]), dtype=np.complex128) + product[0] = vals[0] * state[cols[0]] + + for l in range(self.n_qubits): + p = self.pauli.string[self.n_qubits - l - 1] + pow_of_two = 1 << l + + new_slice = slice(pow_of_two, 2*pow_of_two) + old_slice = slice(0, pow_of_two) + + match p: + case "I": + cols[new_slice] = cols[old_slice] + pow_of_two + vals[new_slice] = vals[old_slice] + case "X": + cols[new_slice] = cols[old_slice] - pow_of_two + vals[new_slice] = vals[old_slice] + case "Y": + cols[new_slice] = cols[old_slice] - pow_of_two + vals[new_slice] = -vals[old_slice] + case "Z": + cols[new_slice] = cols[old_slice] + pow_of_two + vals[new_slice] = -vals[old_slice] + + vals[new_slice] *= self.pauli.weight + product[new_slice] = vals[new_slice, np.newaxis] * state[cols[new_slice]] + + return product + + +def sparse_pauli_multiply(pauli_string: SparsePauliString, state: np.ndarray) -> np.ndarray: + if state.ndim == 1: + return pauli_string.weight * pauli_string.values * state[pauli_string.columns] + elif state.ndim == 2: + return pauli_string.weight * pauli_string.values[:, np.newaxis] * state[pauli_string.columns] + else: + raise ValueError("state must be a 1D or 2D array") + + +def dense_pauli_string(): + pass + + +def dense_pauli_multiply(): + pass