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Merged
fgfuchs merged 3 commits into from
Aug 25, 2025
Merged

Add stabilizer #34

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e1ef65f
Add stabilizer
ScoomenstheMumens Aug 25, 2025
2aac80f
Add stabilizer
ScoomenstheMumens Aug 25, 2025
ef0a205
Add stabilizer
ScoomenstheMumens Aug 25, 2025
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178 changes: 103 additions & 75 deletions quantumreservoirpy/stabilizer.py
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
from itertools import combinations, product
import numpy as np
from typing import Iterable
import random

from qiskit import QuantumCircuit, ClassicalRegister, QuantumRegister, AncillaRegister
from qiskit.quantum_info import random_clifford, Clifford, Pauli
from qiskit.circuit.library import PauliEvolutionGate

from quantumreservoirpy.util import randomIsing, get_Ising_circuit
from quantumreservoirpy.reservoirs import Static

from typing import Iterable


class Stabilizer(Static):
def __init__(
self,
Expand All @@ -22,16 +22,20 @@ def __init__(
memory=np.inf,
backend=None,
degree=1,
stab_method='random',
stab_deg=1,
num_reservoirs=1,
standard=False,
isingparams=None,
decode=True, # danger zone: this is only for testing
) -> None:
super().__init__(
n_qubits + 1, memory, backend, degree=degree, num_reservoirs=num_reservoirs
n_qubits , memory, backend, degree=degree, num_reservoirs=num_reservoirs
)
self.n_meas = n_meas
self.decode = decode
self.stab_method=stab_method
self.stab_deg=stab_deg

if not isingparams:
steps = 1
Expand Down Expand Up @@ -61,83 +65,111 @@ def __init__(
self.tableau = tableau
else:
self.tableau = Stabilizer.generate_tableau(
n_qubits, n_meas, codestate_preparation_circ
n_qubits, n_meas,self.stab_deg,self.stab_method,codestate_preparation_circ
)

def before(self, circuit):
if self.decode:
circuit.add_register(AncillaRegister(self.n_meas))
circuit.add_register(AncillaRegister(1))

def during(self, circuit, timestep, reservoirnumber):
circuit.barrier()

# encode
for k in range(self.n_meas):
beta = 3**k
beta = 3**(k/self.n_meas)/2*np.pi
pauliop = Pauli(self.tableau["destabilizer"][k])
evo = PauliEvolutionGate(pauliop, -beta / 2 * np.pi * timestep)
circuit.append(evo, range(self.n_qubits - 1))

evo = PauliEvolutionGate(pauliop, -beta * timestep)
circuit.append(evo, range(self.n_qubits ))
circuit.barrier()
# reservoir
circuit.append(self.U[reservoirnumber], range(self.n_qubits - 1))
circuit.append(self.U[reservoirnumber], range(self.n_qubits))

# decode
cr = ClassicalRegister(self.n_meas)
circuit.add_register(cr)

if self.decode:
Stabilizer.decoder(circuit, self.tableau)

@staticmethod
def generate_tableau(
n_qubits: int,
n_meas: int,
codestate_preparation_circ: Iterable[QuantumCircuit] | None = None,
stab_deg: int,
stab_method: str,
codestate_preparation_circ: Iterable[QuantumCircuit] | None = None
):
"""generates a tableau for a stabilizer code based on 2**k codestate preparation circuits"""

logical_qubits = n_qubits - n_meas # also called k

if codestate_preparation_circ == None: # generate random stabilizer code
tableau = random_clifford(n_qubits).to_dict()

# turn the last k stabilizers into logical Zs
# tableau["logical_z"] = tableau["stabilizer"][n_meas:] #these are just for QEC fun, not useful here
tableau["stabilizer"] = tableau["stabilizer"][:n_meas]

# turn the last k destabilizers into logical Xs
# tableau["logical_x"] = tableau["destabilizer"][n_meas:]
tableau["destabilizer"] = tableau["destabilizer"][:n_meas]

elif len(codestate_preparation_circ) != 2**logical_qubits:
print(
"Error : number of code state preparation circuits does not match the dimension of the codespace"
)
return

if stab_method == 'random':
print('ok')
"""generates a tableau for a stabilizer code based on 2**k codestate preparation circuits"""

logical_qubits = n_qubits - n_meas # also called k

if codestate_preparation_circ == None: # generate random stabilizer code
tableau = random_clifford(n_qubits).to_dict()

# turn the last k stabilizers into logical Zs
# tableau["logical_z"] = tableau["stabilizer"][n_meas:] #these are just for QEC fun, not useful here
tableau["stabilizer"] = tableau["stabilizer"][:n_meas]

# turn the last k destabilizers into logical Xs
# tableau["logical_x"] = tableau["destabilizer"][n_meas:]
tableau["destabilizer"] = tableau["destabilizer"][:n_meas]

elif len(codestate_preparation_circ) != 2**logical_qubits:
print(
"Error : number of code state preparation circuits does not match the dimension of the codespace"
)
return

else:
tableau = Clifford(codestate_preparation_circ[0]).to_dict()
for circ in codestate_preparation_circ[1:]:
circ_tableau = Clifford(circ).to_dict()
to_pop = []

for i in range(len(tableau["stabilizer"])):
if tableau["stabilizer"][i] not in circ_tableau["stabilizer"]:
to_pop.append(i)

for i in to_pop:
tableau["stabilizer"].pop(i)
tableau["destabilizer"].pop(i)

# check the stabilizer has the right dimension
if (
len(tableau["stabilizer"]) != n_meas
or len(tableau["destabilizer"]) != n_meas
):
print("Error : something went wrong with tableau generation")
print(tableau)

else:
tableau = Clifford(codestate_preparation_circ[0]).to_dict()
for circ in codestate_preparation_circ[1:]:
circ_tableau = Clifford(circ).to_dict()
to_pop = []

for i in range(len(tableau["stabilizer"])):
if tableau["stabilizer"][i] not in circ_tableau["stabilizer"]:
to_pop.append(i)

for i in to_pop:
tableau["stabilizer"].pop(i)
tableau["destabilizer"].pop(i)
deg=stab_deg
stabilizers = []
destabilizers = []
for i in range(n_qubits - deg + 1):
pauli_z = ["I"] * n_qubits
pauli_x = ["I"] * n_qubits

# fill in Z’s and X’s
for j in range(deg):
pauli_z[i + j] = "Z"
pauli_x[i + j] = "X"

stabilizers.append("+" + "".join(pauli_z))
destabilizers.append("+" + "".join(pauli_x))
indices = random.sample(range(len(stabilizers)), n_meas)

# Extract stabilizers and destabilizers at those indices
stabs = [stabilizers[i] for i in indices]
destabs = [destabilizers[i] for i in indices]
tableau= {
"stabilizer": stabs,
"destabilizer": destabs,
}

print(tableau)

# check the stabilizer has the right dimension
if (
len(tableau["stabilizer"]) != n_meas
or len(tableau["destabilizer"]) != n_meas
):
print("Error : something went wrong with tableau generation")
print(tableau)

return tableau

@staticmethod
Expand Down Expand Up @@ -217,29 +249,25 @@ def decoder(circuit: QuantumCircuit, code_tableau: dict):
circuit.barrier()

# syndrome measurement operations
circuit.reset(ar)
circuit.h(ar)

for j in range(n_meas):
circuit.reset(ar)
circuit.h(ar)
P = code_tableau["stabilizer"][j]
if P[0] == -1:
circuit.z(ar[j])
for i in range(1, len(P)):
if P[i] == "X":
circuit.cx(ar[j], qr[i - 1])
elif P[i] == "Y":
circuit.cy(ar[j], qr[i - 1])
elif P[i] == "Z":
circuit.cz(ar[j], qr[i - 1])

circuit.h(ar)

for j in range(n_meas):
circuit.measure(ar[j], cr[j])
P_aux=P[1:][::-1]
if P[0] == str('-'):
circuit.z(ar)
for i in range(0, len(P_aux)):
if P_aux[i] == "X":
circuit.cx(ar, qr[i])
elif P_aux[i] == "Y":
circuit.cy(ar, qr[i])
elif P_aux[i] == "Z":
circuit.cz(ar, qr[i])

circuit.h(ar)
circuit.measure(ar, cr[j])
circuit.barrier()

for j in range(n_meas):
with circuit.if_test((cr[j], 1)):
circuit.pauli(code_tableau["destabilizer"][j][1:], qr[:-1])

circuit.pauli(code_tableau["destabilizer"][j][1:], qr)
return circuit