def __init__(self,
lhs: QuantumRegister,
rhs: QuantumRegister,
output_carry: QubitType,
input_carry: QubitType,
qcirc: QuantumCircuit = None):
"""Initialise the AddRCGate class.
Implements the Ripple-Carry Adder presented in "A new quantum ripple-carry addition circuit"
and written by Steven A. Cuccaro, Thomas G. Draper, Samuel A. Kutin and David Petrie Moulton
in 2008.
Parameters:
lhs (QuantumRegister) left-hand side.
rhs (QuantumRegister) right-hand side AND result.
output_carry (QuantumRegister, int) set to 1 if the addition overflowed.
input_carry (QubitType) input_carry qubit.
qcirc (QuantumCircuit) the circuit on which to add the gates.
"""
used_qubits = [
qubit[i] for qubit in [lhs, rhs] for i in range(len(qubit))
] + [output_carry, input_carry]
super().__init__(
self.__class__.__name__, # name
[], # parameters
used_qubits, # qubits
qcirc) # circuit
qubit_number = min(len(lhs), len(rhs))
# qubit_number is the number of qubits we will use, so it cost nothing to check.
lhs.check_range(qubit_number - 1)
rhs.check_range(qubit_number - 1)
_maj(self, input_carry, rhs[0], lhs[0], qcirc)
for i in range(1, qubit_number):
_maj(self, lhs[i - 1], rhs[i], lhs[i], qcirc)
self.cx(lhs[qubit_number - 1], output_carry)
for i in range(qubit_number - 1, 0, -1):
_uma(self, lhs[i - 1], rhs[i], lhs[i], qcirc)
_uma(self, input_carry, rhs[0], lhs[0], qcirc)
def __init__(self,
lhs: QuantumRegister,
rhs: QuantumRegister,
output_carry: QubitType,
ancilla: QuantumRegister,
qcirc: QuantumCircuit = None):
"""Initialize the AddCQP class.
Implements the CQP adder presented in "Quantum Plain and Carry Look-Ahead Adders"
written by Kai-Wen Cheng and Chien-Cheng Tseng in 2002.
The implementation is FAR from optimal, this algorithm is a naive algorithm to
add 2 quantum registers.
Parameters:
lhs (QuantumRegister) left-hand side.
rhs (QuantumRegister) right-hand side.
output_carry (QuantumRegister, int) set to 1 if the addition overflowed.
ancilla (QuantumRegister) ancilla register: should contain at least N qubits.
qcirc (QuantumCircuit) the associated circuit.
"""
used_qubits = [
qubit[i] for qubit in [lhs, rhs, ancilla]
for i in range(len(qubit))
] + [output_carry]
super().__init__(
self.__class__.__name__, # name
[], # parameters
used_qubits, # qubits
qcirc) # circuit
qubit_number = min([len(lhs), len(rhs), len(ancilla)])
# qubit_number is the number of qubits we will use, so it cost nothing to check.
lhs.check_range(qubit_number - 1)
rhs.check_range(qubit_number - 1)
ancilla.check_range(qubit_number - 1)
# 1. Compute the final carry
for i in range(qubit_number - 1):
_carry(self, ancilla[i], lhs[i], rhs[i], ancilla[i + 1], qcirc)
_carry(self, ancilla[qubit_number - 1], lhs[qubit_number - 1],
rhs[qubit_number - 1], output_carry, qcirc)
self.cx(lhs[qubit_number - 1], rhs[qubit_number - 1])
# 2. Perform the additions with the computed carry bits and reverse
# the carry operation
for i in range(qubit_number - 1, 0, -1):
_bit_add_without_carry(self, ancilla[i], lhs[i], rhs[i], qcirc)
_icarry(self, ancilla[i - 1], lhs[i - 1], rhs[i - 1], ancilla[i],
qcirc)
_bit_add_without_carry(self, ancilla[0], lhs[0], rhs[0], qcirc)
