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PhasePolynomial

QuICT.qcda.optimization.clifford_rz_optimization.PhasePolynomial 

PhasePolynomial(gates)

Phase polynomial representation of a quantum circuit that only contains X, CX and Rz gates.

Create a phase polynomial from given circuit. The circuit can only contain Controlled-X and Rz gates.

Parameters:

  • gates (DAG) –

    Circuit represented by this polynomial

Source code in QuICT/qcda/optimization/clifford_rz_optimization/phase_poly.py 
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def __init__(self, gates):
    """
    Create a phase polynomial from given circuit. The circuit can only contain
    Controlled-X and Rz gates.

    Args:
        gates (DAG): Circuit represented by this polynomial
    """

    self.phases = {}
    self.gates = []
    self.size = gates.width()
    self._build_poly(gates)

get_circuit 

get_circuit(epsilon=1e-10) -> Circuit

Generate a circuit of minimal size that implements the phase polynomial

Returns:

  • Circuit ( Circuit ) –

    Circuit equivalent to this polynomial

Source code in QuICT/qcda/optimization/clifford_rz_optimization/phase_poly.py 
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def get_circuit(self, epsilon=1e-10) -> Circuit:
    """
    Generate a circuit of minimal size that implements the phase polynomial

    Returns:
        Circuit: Circuit equivalent to this polynomial
    """
    max_monomial = max(self.phases.keys()) if len(self.phases.keys()) > 0 else 1
    circ = Circuit(self.size)
    visited = set()
    for qubit_ in range(int(np.ceil(log2(max_monomial + 1))) + 1):
        if (1 << qubit_) in self.phases:
            if abs(self.phases[1 << qubit_]) > epsilon:
                Rz(self.phases[1 << qubit_]) | circ(qubit_)
            visited.add(1 << qubit_)

    monomials = {}
    for gate_ in self.gates:
        gate_: BasicGate
        for qubit_ in chain(gate_.cargs, gate_.targs):
            if qubit_ not in monomials:
                monomials[qubit_] = 1 << (qubit_ + 1)

        if gate_.qasm_name == 'cx':
            monomials[gate_.targ] = monomials[gate_.targ] ^ monomials[gate_.carg]
        elif gate_.qasm_name == 'x':
            monomials[gate_.targ] = monomials[gate_.targ] ^ 1

        gate_.copy() | circ(list(chain(gate_.cargs, gate_.targs)))
        cur_phase = monomials[gate_.targ] >> 1
        cur_sign = -1 if (monomials[gate_.targ] & 1) else 1

        if cur_phase in self.phases and cur_phase not in visited:
            if abs(self.phases[cur_phase]) > epsilon:
                Rz(cur_sign * self.phases[cur_phase]) | circ(gate_.targ)
            visited.add(cur_phase)

    return circ