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NQubitALU.py
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NQubitALU.py
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import numpy as np
import qiskit
from qiskit.visualization import plot_state_city
# import qiskit.circuits.library as lib
from qiskit import QuantumRegister
from typing import Optional, List
class HalfAdder(qiskit.circuit.Gate):
def __init__(self) -> None:
super().__init__('halfAdder', 4, [])
def _define(self):
"""
gate halfAdder(a, b, sum, carry)
{
cx a, sum;
cx b, sum;
ccx a, b, carry;
}
"""
from qiskit.circuit.quantumcircuit import QuantumCircuit
q = qiskit.QuantumRegister(4, name='q')
qc = qiskit.QuantumCircuit(q, name=self.name)
# XOR q0, q1 to q2
qc.cx(0, 2)
qc.cx(1, 2)
# AND q0, q1 to q3
qc.ccx(0, 1, 3)
self.definition = qc
# if self.num_variable_qubits < 4:
# raise ValueError
class FullAdder(qiskit.circuit.Gate):
def __init__(self) -> None:
super().__init__('fullAdder', 8, [])
def _define(self):
"""
gate halfAdder(a, b, cin, cout, sum, ancilla1, ancilla2, ancilla3)
{
cx a, ancilla1;
cx b, ancilla1;
cx cin, cout;
cx sum, cout;
ccx a, b, ancilla2;
ccx cin, ancilla1, ancilla3;
cx ancilla3, cout;
cx ancilla2, cout;
ccx ancilla2, ancilla3, cout;
}
"""
from qiskit.circuit.quantumcircuit import QuantumCircuit
q = qiskit.QuantumRegister(8, name='q')
qc = qiskit.QuantumCircuit(q, name=self.name)
# XOR q0, q1 to q5
qc.cx(0, 5)
qc.cx(1, 5)
# XOR q2, q5 to q4
qc.cx(2, 4)
qc.cx(5, 4)
# AND q0, q1 to q6
qc.ccx(0, 1, 6)
# AND q2, q5 to q7
qc.ccx(2, 5, 7)
# OR q7, q6, q3
qc.cx(7, 3)
qc.cx(6, 3)
qc.ccx(7, 6, 3)
self.definition = qc
class TwoQubitALU(qiskit.QuantumCircuit):
def __init__(self,
num_qubits: int = 12) -> None:
"""Return a circuit implementing a Two Qubit ALU, with input qubits in the form (a0, a1, b0, b1, s0, s1, c0, c1, sb, ancilla1, ancilla2, ancilla3)
Args:
num_qubits: the width of circuit.
Raises:
ValueError: If the number of qubits is not right.
"""
super().__init__(num_qubits, name="ALU(2)")
if num_qubits != 12:
raise ValueError("ALU(2) requires 13 bits")
q = self.qregs[0]
# B0 XOR SB to B0 (use ancilla 1, swap b0, ancilla1, then reset ancilla1)
self.cx(2, 9)
self.cx(8, 9)
self.swap(2, 9)
self.reset([9]*10)
# B1 XOR SB TO B1 (use ancilla 1, swap b1, ancilla2, then reset ancilla2)
self.cx(3, 10)
self.cx(8, 10)
self.swap(3, 10)
self.reset([10]*10)
# (a0, a1, b0, b1, s0, s1, c0, c1, sb, ancilla1, ancilla2, ancilla3)
# a, b, cin, cout, sum, ancilla1, ancilla2, ancilla3
# SUM A0, B0, reset ancillas
self.append(FullAdder(), [q[i] for i in [0, 2, 8, 6, 4, 9, 10, 11]]) #a0, b0, sb, c0, s0, ancillas
self.reset([9]*10)
self.reset([10]*10)
self.reset([11]*10)
# SUM A1, B1, reset ancillas
self.append(FullAdder(), [q[i] for i in [1, 3, 6, 7, 5, 9, 10, 11]])
self.reset([9]*10)
self.reset([10]*10)
self.reset([11]*10)
class NQubitALU(qiskit.circuit.library.BlueprintCircuit):
def __init__(self,
registerA: qiskit.QuantumRegister,
registerB: qiskit.QuantumRegister,
registerS: qiskit.QuantumRegister,
registerSB: qiskit.QuantumRegister,
registerC: qiskit.QuantumRegister,
registerAncilla: qiskit.QuantumRegister,
num_qubits: Optional[int] = None,
name: str = 'ALU(N)') -> None:
"""Return a circuit implementing a simple N Qubit ALU (named ALU(N)), with input qubits in the form (a0, ... an, b0, b ...bn, s0...sn, c0...cn, sb, ancilla1, ancilla2, ancilla3)
Args:
registerA: First Quantum register of size N, which will be the first string to operate on.
registerB: Second Quantum register of size N, which will be the second string to operate on.
registerS: Third Quantum register of size N, which will contain the output string.
registerSB: Single qubit quantum register which controls between operations ADD and SUB.
registerC: Fourth Quantum register of size N, which contains the carry bits.
registerAncilla: Quantum register of size 3 to operate Ancillas.
Raises:
CircuitError: if the xor bitstring exceeds available qubits.
Reference Circuit:
.. jupyter-execute::
:hide-code:
from qiskit.circuit.library import XOR
import qiskit.tools.jupyter
circuit = XOR(5, seed=42)
%circuit_library_info circuit
"""
self.registerA = registerA
self.registerB = registerB
self.registerS = registerS
self.registerSB = registerSB
self.registerC = registerC
self.registerAncilla = registerAncilla
self._num_qubits = None
self.num_qubits = registerA.size # Size of the Nbits to operate on
self._name = f'ALU({self.registerA.size})'
self.qregs = [self.registerA, self.registerB, self.registerS, self.registerSB, self.registerC, self.registerAncilla]
super().__init__(*self.qregs, name=self._name)
self.qregs = [self.registerA, self.registerB, self.registerS, self.registerSB, self.registerC, self.registerAncilla]
@property
def num_qubits(self) -> int:
"""The number of qubits to be summed.
Returns:
The number of qubits per main register.
"""
return self._num_qubits
@num_qubits.setter
def num_qubits(self, num_qubits: int) -> None:
"""Set the number of qubits in the registers of the ALU operation.
Args:
num_qubits: The new number of qubits.
"""
if self._num_qubits is None or num_qubits != self._num_qubits:
self._invalidate()
self._num_qubits = num_qubits
self._reset_registers()
def _reset_registers(self):
qr_A = self.registerA
qr_B = self.registerB
qr_S = self.registerS
qr_SB = self.registerSB
qr_C = self.registerC
qr_An = self.registerAncilla
self.qregs = [qr_A, qr_B, qr_S, qr_SB, qr_C, qr_An]
@property
def num_ancilla_qubits(self) -> int:
"""The number of ancilla qubits required to implement the ALU(operation).
Returns:
The number of ancilla qubits in the circuit.
"""
return 3
@property
def num_carry_qubits(self) -> int:
"""The number of carry qubits required to compute the ALU.
Note that this is not necessarily equal to the number of ancilla qubits, these can
be queried using ``num_ancilla_qubits``.
Returns:
The number of carry qubits required to compute the sum.
"""
return self.num_qubits
def _check_configuration(self, raise_on_failure=True):
valid = True
if self._num_qubits is None:
valid = False
if raise_on_failure:
raise AttributeError('The input register has not been set.')
if not (self.registerA.size and self.registerB.size and self.registerS.size and self.registerC.size):
valid = False
if raise_on_failure:
raise ValueError('Register sizes are not equal.')
if self.registerSB.size != 1:
valid = False
if raise_on_failure:
raise ValueError('Control qubit register must be of size 1.')
if self.registerAncilla.size < 3:
valid = False
if raise_on_failure:
raise ValueError('Ancilla register needs at least three qubits.')
return valid
def _build(self):
super()._build()
qr_A = self.registerA
qr_B = self.registerB
qr_S = self.registerS
qr_SB = self.registerSB
qr_carry = self.registerC
qr_ancilla = self.registerAncilla
for qubit in qr_ancilla:
self.reset([qubit]*1)
for B_index in range(qr_B.size):
self.cx(qr_B[B_index], qr_ancilla[0])
self.cx(qr_SB[0], qr_ancilla[0])
self.swap(qr_B[B_index], qr_ancilla[0])
self.reset([qr_ancilla[0]]*1)
for A_index in range(qr_A.size):
if A_index == 0:
self.append(FullAdder(), [qubit for qubit in [qr_A[A_index], qr_B[A_index], qr_SB, qr_carry[A_index],
qr_S[A_index], qr_ancilla[0], qr_ancilla[1], qr_ancilla[2]]]) #a0, b0, sb, c0, s0, ancillas
self.reset([qr_ancilla[0]]*1)
self.reset([qr_ancilla[1]]*1)
self.reset([qr_ancilla[2]]*1)
else:
self.append(FullAdder(), [qubit for qubit in [qr_A[A_index], qr_B[A_index], qr_carry[A_index - 1], qr_carry[A_index],
qr_S[A_index], qr_ancilla[0], qr_ancilla[1], qr_ancilla[2]]]) #a0, b0, sb, c0, s0, ancillas
self.reset([qr_ancilla[0]]*1)
self.reset([qr_ancilla[1]]*1)
self.reset([qr_ancilla[2]]*1)
def set_register_from_classical_register(quantumRegister: qiskit.QuantumRegister, classicalRegister: qiskit.ClassicalRegister):
'''
Sets the qubits in a quantum register to the classical values of a classic register.
Cannot be implemented as of current Qiskit version without measuring a circuit.
Input:
quantumRegister: A quantum register in its ground state.
classicalRegister: Target register to set.
'''
if quantumRegister.size != classicalRegister.size:
raise ValueError("Classic register and quantum register are not of same size")
pass
def set_quantum_register_from_string(circuit: qiskit.QuantumCircuit,
quantumRegister: qiskit.QuantumRegister,
input_string: str,
n_resets: int = 1):
"""
Resets quantumRegister and sets it to the values of the input string. Appends the necessary gates into circuit.
"""
N = len(input_string)
if quantumRegister.size != N:
raise ValueError("Classic register and quantum register are not of same size")
circuit.reset([qubit for qubit in quantumRegister]*n_resets)
for characters in range(N-1, -1, -1):
if input_string[characters] == '1':
circuit.x(quantumRegister[N - characters - 1])
if __name__ == "__main__":
from qiskit import Aer
import qiskit
import itertools
from qiskit.result.utils import count_keys
# Define length of strings, as well as the strings you would like to sum and the control bit
N = 2
stringA = '10'
stringB = '01'
stringSB = '0'
# Initialize quantum and classic registers
registerA = qiskit.QuantumRegister(N)
registerB = qiskit.QuantumRegister(N)
registerS = qiskit.QuantumRegister(N)
registerSB = qiskit.QuantumRegister(1)
registerC = qiskit.QuantumRegister(N)
registerAnc = qiskit.QuantumRegister(3)
measurementRegister = qiskit.ClassicalRegister(4+4*N)
regs = [registerA, registerB, registerS, registerSB, registerC, registerAnc]
flat_regs = list(itertools.chain(*[register[:] for register in regs]))
# Create a circuit
circuit = qiskit.QuantumCircuit(*regs, measurementRegister, name = 'ALU')
# Set input registers
set_quantum_register_from_string(circuit, registerA, stringA)
set_quantum_register_from_string(circuit, registerB, stringB)
# Set SB to choose between add or sub
# If dding a Hadamard gate, then calculate both ADD and SUB
set_quantum_register_from_string(circuit, registerSB, stringSB)
circuit.h(registerSB)
# Add NQubitALU to the circuit
circuit.append(NQubitALU(*regs).to_instruction(), flat_regs)
# Add measurement operations to the circuit
circuit.barrier()
circuit.measure(range(4+4*N), range(4+4*N))
# Display the circuit
print(circuit)
# Use Aer's qasm_simulator
simulator = Aer.get_backend('qasm_simulator')
n_shots = 1024
# Execute the circuit on the qasm simulator
job = qiskit.execute(circuit, simulator, shots=n_shots, meas_return = 'single')
# Grab results from the job
result = job.result()
# Return counts
counts = result.get_counts(circuit)
bit_results = list(counts.keys())
print(f"\nInputs are A = {stringA}, B = {stringB}, SB = {stringSB}")
print("\nTotal counts are:", counts)
print("\nSum of A + (SB XOR B) is: \n")
for result in bit_results:
print(f"{result[4+N:4+2*N]} with a number of counts {counts.get(result)}/{n_shots}")