def carry_gate():
carry_circ = AncillaCircuit(4)
(c0, a, b, c1) = (carry_circ.qubits[0], carry_circ.qubits[1],
carry_circ.qubits[2], carry_circ.qubits[3])
carry_circ.ccx(a, b, c1)
carry_circ.append(neg_mct_gate(), [c0, a, b, c1])
return carry_circ.to_ancilla_gate()
def neg_mct_gate(lneg):
neg_mct = AncillaCircuit(3)
for i in lneg:
neg_mct.x(i)
neg_mct.ccx(0, 1, 2)
for i in lneg:
neg_mct.x(i)
return neg_mct.to_ancilla_gate(True)
def makeIntegerComparator(num_state_qubits, value, geq=True, with_uncomp=True):
"""Build the comparator circuit."""
or_gate = OR(2).to_gate()
qr_state = QuantumRegister(num_state_qubits, name='state')
q_compare = QuantumRegister(1, name='compare')
circuit = AncillaCircuit(qr_state, q_compare)
circuit.addQfreeGate(or_gate)
qr_ancilla = circuit.new_ancilla_register(
num_state_qubits - 1, name='ancilla') if num_state_qubits > 1 else None
if value <= 0: # condition always satisfied for non-positive values
if geq: # otherwise the condition is never satisfied
circuit.x(q_compare)
# condition never satisfied for values larger than or equal to 2^n
elif value < pow(2, num_state_qubits):
if num_state_qubits > 1:
twos = _get_twos_complement(num_state_qubits, value)
for i in range(num_state_qubits):
if i == 0:
if twos[i] == 1:
circuit.cx(qr_state[i], qr_ancilla[i])
elif i < num_state_qubits - 1:
if twos[i] == 1:
circuit.append(
or_gate,
[qr_state[i], qr_ancilla[i - 1], qr_ancilla[i]])
else:
circuit.ccx(qr_state[i], qr_ancilla[i - 1],
qr_ancilla[i])
else:
if twos[i] == 1:
circuit.append(
or_gate,
[qr_state[i], qr_ancilla[i - 1], q_compare])
else:
circuit.ccx(qr_state[i], qr_ancilla[i - 1], q_compare)
# flip result bit if geq flag is false
if not geq:
circuit.x(q_compare)
else:
# num_state_qubits == 1 and value == 1:
circuit.cx(qr_state[0], q_compare)
# flip result bit if geq flag is false
if not geq:
circuit.x(q_compare)
else:
if not geq: # otherwise the condition is never satisfied
circuit.x(q_compare)
return circuit
def makesMult(num_qubits):
#[x, y, b] b = x * y; x, y, and b all made of num_qubits each
#returns an AncillaCircuit, without uncomputation
b = QuantumRegister(num_qubits)
y = QuantumRegister(num_qubits)
x = QuantumRegister(num_qubits)
circuit = AncillaCircuit(b, y, x)
for i, x_i in enumerate(x):
# a = (y*(2**i))*x_i
a = circuit.new_ancilla_register(num_qubits)
for a_qubit, y_qubit in zip(a[i:], y[:num_qubits - i]):
circuit.ccx(x_i, y_qubit, a_qubit)
# b += a
circuit.append(
makesAdder(num_qubits).to_ancilla_gate(), [*a[:], *b[:]])
return circuit
def neg_mct_gate():
neg_mct = AncillaCircuit(4)
neg_mct.cx(1, 2)
neg_mct.ccx(0, 2, 3)
neg_mct.cx(1, 2)
return neg_mct.to_ancilla_gate(True)
def makeWeightedAdder(num_state_qubits, weights):
# Straightforward implementation using Unqomp, uses less gate but more qubits
num_sum_qubits = int(np.floor(np.log2(sum(weights))) +
1) if sum(weights) > 0 else 1
# The number of sum qubits in the circuit
num_carry_qubits = num_sum_qubits - 1
# The number of carry qubits required to compute the sum.
for i, weight in enumerate(weights):
if not np.isclose(weight, np.round(weight)):
raise ValueError('Non-integer weights are not supported!')
weights[i] = np.round(weight)
num_result_qubits = num_state_qubits + num_sum_qubits
qr_state = QuantumRegister(num_state_qubits, name='state')
qr_sum = QuantumRegister(num_sum_qubits, name='sum')
circuit = AncillaCircuit(qr_state, qr_sum)
#print(num_state_qubits)
#print(num_sum_qubits)
# loop over state qubits and corresponding weights
for i, weight in enumerate(weights):
# only act if non-trivial weight
if np.isclose(weight, 0):
continue
# get state control qubit
q_state = qr_state[i]
# get bit representation of current weight
weight_binary = '{0:b}'.format(int(weight)).rjust(num_sum_qubits,
'0')[::-1]
#print("carry qb" + str(num_carry_qubits))
qr_carry = circuit.new_ancilla_register(num_carry_qubits,
name="anccarryite" + str(i))
# loop over bits of current weight and add them to sum and carry registers
for j, bit in enumerate(weight_binary):
if bit == '1':
if num_sum_qubits == 1:
circuit.cx(q_state, qr_sum[j])
elif j == 0:
# compute (q_sum[0] + 1) into (q_sum[0], q_carry[0])
# - controlled by q_state[i]
circuit.ccx(q_state, qr_sum[j], qr_carry[j])
circuit.cx(q_state, qr_sum[j])
elif j == num_sum_qubits - 1:
# compute (q_sum[j] + q_carry[j-1] + 1) into (q_sum[j])
# - controlled by q_state[i] / last qubit,
# no carry needed by construction
circuit.cx(q_state, qr_sum[j])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
# compute (q_sum[j] + q_carry[j-1] + 1) into (q_sum[j], q_carry[j])
# - controlled by q_state[i]
circuit.mcx([q_state, qr_sum[j], qr_carry[j - 1]],
qr_carry[j],
negated_ctrls=[1, 2])
circuit.cx(q_state, qr_carry[j])
circuit.cx(q_state, qr_sum[j])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
if num_sum_qubits == 1:
pass # nothing to do, since nothing to add
elif j == 0:
pass # nothing to do, since nothing to add
elif j == num_sum_qubits - 1:
# compute (q_sum[j] + q_carry[j-1]) into (q_sum[j])
# - controlled by q_state[i] / last qubit,
# no carry needed by construction
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
# compute (q_sum[j] + q_carry[j-1]) into (q_sum[j], q_carry[j])
# - controlled by q_state[i]
circuit.mcx([q_state, qr_sum[j], qr_carry[j - 1]],
qr_carry[j])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
return circuit
def makeWeightedAdderWOExtraCtrlsQb(num_state_qubits, weights):
# Implementation using Unqomp but enforcing local uncomputation, uses less qubits, but is not fully modular, ancillas have to be taken care of manually
def neg_mct_gate(negated_ctrls):
#circuit.mcx([q_state, qr_sum[j], qr_carry[j - 1]], qr_carry[j], negated_ctrls = [1, 2])
ctrls = QuantumRegister(3)
anc = QuantumRegister(1)
targ = QuantumRegister(1)
neg_mct = QuantumCircuit(ctrls, anc, targ) #[ctrl0...ctrl3, anc, targ]
for i in negated_ctrls:
neg_mct.x(ctrls[i])
neg_mct.mcx(ctrls, targ, anc, mode='basic')
for i in negated_ctrls:
neg_mct.x(ctrls[i])
return neg_mct.to_gate()
num_sum_qubits = int(np.floor(np.log2(sum(weights))) +
1) if sum(weights) > 0 else 1
# The number of sum qubits in the circuit
num_carry_qubits = num_sum_qubits - 1
# The number of carry qubits required to compute the sum.
for i, weight in enumerate(weights):
if not np.isclose(weight, np.round(weight)):
raise ValueError('Non-integer weights are not supported!')
weights[i] = np.round(weight)
num_result_qubits = num_state_qubits + num_sum_qubits
qr_state = QuantumRegister(num_state_qubits, name='state')
qr_sum = QuantumRegister(num_sum_qubits, name='sum')
qr_ctrl = QuantumRegister(1, name='ctrl')
circuit = AncillaCircuit(qr_state, qr_sum, qr_ctrl)
neg_mct_g = neg_mct_gate([1, 2])
mct_g = neg_mct_gate([])
circuit.addQfreeGate(neg_mct_g)
circuit.addQfreeGate(mct_g)
# loop over state qubits and corresponding weights
for i, weight in enumerate(weights):
# only act if non-trivial weight
if np.isclose(weight, 0):
continue
# get state control qubit
q_state = qr_state[i]
# get bit representation of current weight
weight_binary = '{0:b}'.format(int(weight)).rjust(num_sum_qubits,
'0')[::-1]
#print("carry qb" + str(num_carry_qubits))
qr_carry = circuit.new_ancilla_register(num_carry_qubits,
name="anccarryite" + str(i))
# loop over bits of current weight and add them to sum and carry registers
for j, bit in enumerate(weight_binary):
if bit == '1':
if num_sum_qubits == 1:
circuit.cx(q_state, qr_sum[j])
elif j == 0:
# compute (q_sum[0] + 1) into (q_sum[0], q_carry[0])
# - controlled by q_state[i]
circuit.ccx(q_state, qr_sum[j], qr_carry[j])
circuit.cx(q_state, qr_sum[j])
elif j == num_sum_qubits - 1:
# compute (q_sum[j] + q_carry[j-1] + 1) into (q_sum[j])
# - controlled by q_state[i] / last qubit,
# no carry needed by construction
circuit.cx(q_state, qr_sum[j])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
# compute (q_sum[j] + q_carry[j-1] + 1) into (q_sum[j], q_carry[j])
# - controlled by q_state[i]
circuit.append(neg_mct_g, [
q_state, qr_sum[j], qr_carry[j - 1], qr_ctrl,
qr_carry[j]
])
circuit.cx(q_state, qr_carry[j])
circuit.cx(q_state, qr_sum[j])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
if num_sum_qubits == 1:
pass # nothing to do, since nothing to add
elif j == 0:
pass # nothing to do, since nothing to add
elif j == num_sum_qubits - 1:
# compute (q_sum[j] + q_carry[j-1]) into (q_sum[j])
# - controlled by q_state[i] / last qubit,
# no carry needed by construction
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
else:
# compute (q_sum[j] + q_carry[j-1]) into (q_sum[j], q_carry[j])
# - controlled by q_state[i]
circuit.append(mct_g, [
q_state, qr_sum[j], qr_carry[j - 1], qr_ctrl,
qr_carry[j]
])
circuit.ccx(q_state, qr_carry[j - 1], qr_sum[j])
return circuit