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Mar 14, 2025
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Add seeding for BiRB designs #547

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1ab5552
Add seeding for BiRB designs
Feb 24, 2025
fb304db
Merge branch 'develop' into bugfix-birb-seeding
sserita Mar 13, 2025
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58 changes: 33 additions & 25 deletions pygsti/algorithms/randomcircuit.py
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Original file line number Diff line number Diff line change
Expand Up @@ -769,7 +769,7 @@ def create_random_circuit(pspec, length, qubit_labels=None, sampler='Qeliminatio
layer = sample_circuit_layer_of_one_q_gates(pspec, qubit_labels, *lsargs, rand_state=rand_state)
# For even layers, we sample according to the given distribution
else:
layer = sampler(pspec, qubit_labels, *samplerargs)
layer = sampler(pspec, qubit_labels, *samplerargs, rand_state=rand_state)
circuit.insert_layer_inplace(layer, 0)

circuit.done_editing()
Expand Down Expand Up @@ -1990,7 +1990,7 @@ def create_random_germpower_mirror_circuits(pspec, absolute_compilation, depths,
return circlist, outlist, aux

###begin BiRB tools###
def _stabilizer_to_all_zs(stabilizer, qubit_labels, absolute_compilation):
def _stabilizer_to_all_zs(stabilizer, qubit_labels, absolute_compilation, seed=None):
#inputs:
# - stabilizer: An n-qubit Pauli, represented as a string of X, Y, Z, and Is.
# - qubit_labels: list/tuple of qubit labels
Expand All @@ -1999,6 +1999,8 @@ def _stabilizer_to_all_zs(stabilizer, qubit_labels, absolute_compilation):
# into a Pauli with only Zs and Is.
# - s, layer, p_layer: Symplectic representation of the layer
# - stab_circuit: Layer as a compiled circuit
rng = _np.random.default_rng(seed)

n = len(stabilizer)

symp_reps = _symp.compute_internal_gate_symplectic_representations()
Expand All @@ -2018,7 +2020,7 @@ def _stabilizer_to_all_zs(stabilizer, qubit_labels, absolute_compilation):
stab_layer.append((s_h, p_h))
c.append(_lbl.Label('C12','{}'.format(qubit_labels[i])))
elif stabilizer[i] == 'I':
rand_clifford = str(_np.random.choice(_np.arange(24)))
rand_clifford = str(rng.choice(_np.arange(24)))
s_rand, p_rand = symp_reps['C'+rand_clifford]
stab_layer.append((s_rand, p_rand))
c.append(_lbl.Label('C'+rand_clifford,'{}'.format(qubit_labels[i])))
Expand Down Expand Up @@ -2064,7 +2066,7 @@ def _symplectic_to_pauli(s,p):

return pauli

def _sample_random_pauli(n,pspec = None, absolute_compilation = None, qubit_labels = None, circuit = False, include_identity = False):
def _sample_random_pauli(n,pspec = None, absolute_compilation = None, qubit_labels = None, circuit = False, include_identity = False, seed=None):
# Samples a random Pauli along with a +-1 phase. Returns the Pauli as a list or as a circuit depending
# upon the value of "circuit"
# - n: Number of qubits
Expand All @@ -2077,18 +2079,20 @@ def _sample_random_pauli(n,pspec = None, absolute_compilation = None, qubit_labe
if qubit_labels is not None: qubits = qubit_labels[:] # copy this list
else: qubits = pspec.qubit_labels[:]

rng = _np.random.default_rng(seed)

pauli_list = ['I','X','Y','Z']

if include_identity is False:
while True:
rand_ints = _np.random.randint(0,4,n)
rand_ints = rng.integers(0, 4, n)
if sum(rand_ints) != 0: # make sure we don't get all identities
break
else:
rand_ints = _np.random.randint(0, 4, n)
rand_ints = rng.integers(0, 4, n)

pauli = [pauli_list[i] for i in rand_ints]
if set(pauli) != set('I'): sign = _np.random.choice([-1,1])
if set(pauli) != set('I'): sign = rng.choice([-1,1])
else: sign = 1

if circuit is False:
Expand All @@ -2106,11 +2110,13 @@ def _sample_random_pauli(n,pspec = None, absolute_compilation = None, qubit_labe
return pauli, sign, pauli_circuit


def _select_neg_evecs(pauli, sign):
def _select_neg_evecs(pauli, sign, seed=None):
# Selects the entries in an n-qubit that will be turned be given a -1 1Q eigenstates
# - pauli: The n-qubit Pauli
# - sign: Whether you want a -1 or +1 eigenvector
# Returns: A bitstring whose 0/1 entries specify if you have a +1 or -1 1Q eigenstate
rng = _np.random.default_rng(seed)

n = len(pauli)
identity_bitstring = [0 if i == 'I' else 1 for i in pauli]
nonzero_indices = _np.nonzero(identity_bitstring)[0]
Expand All @@ -2125,10 +2131,10 @@ def _select_neg_evecs(pauli, sign):
choices = _np.arange(start = 0, stop = num_nid, step = 2)
else:
choices = _np.arange(start = 1, stop = num_nid+1, step = 2)
num_neg_evecs = _np.random.choice(choices)
num_neg_evecs = rng.choice(choices)
assert((-1)**num_neg_evecs == sign)

neg_evecs = _np.random.choice(nonzero_indices, num_neg_evecs, replace = False)
neg_evecs = rng.choice(nonzero_indices, num_neg_evecs, replace = False)

bit_evecs = _np.zeros(n)
bit_evecs[neg_evecs] = 1
Expand Down Expand Up @@ -2160,7 +2166,7 @@ def _compose_initial_cliffords(prep_circuit):
composed_layer.append(new_gate)
return composed_layer

def _sample_stabilizer(pauli, sign, absolute_compilation, qubit_labels):
def _sample_stabilizer(pauli, sign, absolute_compilation, qubit_labels, seed=None):
# Samples a random stabilizer of a Pauli, s = s_1 \otimes ... \otimes s_n. For each s_i,
# we perform the following gates:
# - s_i = X: H
Expand All @@ -2176,10 +2182,10 @@ def _sample_stabilizer(pauli, sign, absolute_compilation, qubit_labels):
# preparation circuit, and a pygsti circuit representation of the prep circuit



rng = _np.random.default_rng(seed)

n = len(pauli)
neg_evecs = _select_neg_evecs(pauli, sign)
neg_evecs = _select_neg_evecs(pauli, sign, seed=seed)
assert((-1)**sum(neg_evecs) == sign)
zvals = [0 if neg_evecs[i] == 0 else -1 for i in range(n)]

Expand All @@ -2199,7 +2205,7 @@ def _sample_stabilizer(pauli, sign, absolute_compilation, qubit_labels):
'Z': 'C0'}

x_layer = [symp_reps['I'] if zvals[i] == 0 else symp_reps['X'] for i in range(len(zvals))]
circ_layer = [circ_dict[i] if i in circ_dict.keys() else 'C'+str(_np.random.randint(24)) for i in pauli]
circ_layer = [circ_dict[i] if i in circ_dict.keys() else 'C'+str(rng.integers(24)) for i in pauli]

init_layer = [symp_reps[circ_layer[i]] for i in range(len(pauli))]

Expand Down Expand Up @@ -2257,8 +2263,7 @@ def _determine_sign(s_state, p_state, measurement):


def create_binary_rb_circuit(pspec, clifford_compilations, length, qubit_labels=None, layer_sampling = 'mixed1q2q', sampler='Qelimination',
samplerargs=None, addlocal=False, lsargs=None,
seed=None):
samplerargs=None, addlocal=False, lsargs=None, seed=None):
"""
Generates a "binary randomized benchmarking" (BiRB) circuit.

Expand Down Expand Up @@ -2343,19 +2348,21 @@ def create_binary_rb_circuit(pspec, clifford_compilations, length, qubit_labels=


rand_pauli, rand_sign, pauli_circuit = _sample_random_pauli(n = n, pspec = pspec, qubit_labels=qubit_labels,
absolute_compilation = clifford_compilations,
circuit = True, include_identity = False)
absolute_compilation = clifford_compilations,
circuit = True, include_identity = False, seed=seed+42)

s_inputstate, p_inputstate, s_init_layer, p_init_layer, prep_circuit = _sample_stabilizer(rand_pauli, rand_sign, clifford_compilations, qubit_labels)
s_inputstate, p_inputstate, s_init_layer, p_init_layer, prep_circuit = _sample_stabilizer(rand_pauli, rand_sign, clifford_compilations,
qubit_labels, seed=seed+43)

s_pc, p_pc = _symp.symplectic_rep_of_clifford_circuit(pauli_circuit, pspec=pspec.subset(gate_names_to_include='all', qubit_labels_to_keep=qubit_labels)) #note: if the pspec contains gates not in pyGSTi, this
s_pc, p_pc = _symp.symplectic_rep_of_clifford_circuit(pauli_circuit, pspec=pspec.subset(gate_names_to_include='all',
qubit_labels_to_keep=qubit_labels)) #note: if the pspec contains gates not in pyGSTi, this

# build the initial layer of the circuit
full_circuit = prep_circuit.copy(editable=True)

# Sample a random circuit of "native gates".
if layer_sampling == 'alternating1q2q':
circuit = random_alternating_clifford_circ(pspec, length, qubit_labels=qubit_labels, two_q_gate_density=samplerargs[0])
circuit = random_alternating_clifford_circ(pspec, length, qubit_labels=qubit_labels, two_q_gate_density=samplerargs[0], rand_state=rand_state)
elif layer_sampling == 'mixed1q2q':
circuit = create_random_circuit(pspec=pspec, length=length, qubit_labels=qubit_labels, sampler=sampler,
samplerargs=samplerargs, addlocal=addlocal, lsargs=lsargs, rand_state=rand_state)
Expand Down Expand Up @@ -2386,7 +2393,7 @@ def create_binary_rb_circuit(pspec, clifford_compilations, length, qubit_labels=

# Turn the stabilizer into an all Z and I stabilizer. Append this to the circuit.

s_stab, p_stab, stab_circuit = _stabilizer_to_all_zs(pauli, qubit_labels, clifford_compilations)
s_stab, p_stab, stab_circuit = _stabilizer_to_all_zs(pauli, qubit_labels, clifford_compilations, seed=seed+404)

full_circuit.append_circuit_inplace(stab_circuit)

Expand All @@ -2405,7 +2412,7 @@ def create_binary_rb_circuit(pspec, clifford_compilations, length, qubit_labels=

return outcircuit, measurement, sign

def random_alternating_clifford_circ(pspec, depth, qubit_labels=None, two_q_gate_density=0.25):
def random_alternating_clifford_circ(pspec, depth, qubit_labels=None, two_q_gate_density=0.25, rand_state=None):
"""
Generates a random circuit with composite layers cponsisting of a layer of two-qubit gates followed by
a layer of of single-qubit gates.
Expand Down Expand Up @@ -2443,8 +2450,9 @@ def random_alternating_clifford_circ(pspec, depth, qubit_labels=None, two_q_gate
#sample # benchmarking layers = depth
circ = _cir.Circuit(layer_labels=[], line_labels=qubit_labels, editable=True)
for _ in range(depth):
oneQ_layer = _cir.Circuit([sample_circuit_layer_of_one_q_gates(pspec, qubit_labels = qubit_labels)]).parallelize()
twoQ_layer = _cir.Circuit(sample_circuit_layer_by_edgegrab(pspec, qubit_labels=qubit_labels, two_q_gate_density=two_q_gate_density)).parallelize()
oneQ_layer = _cir.Circuit([sample_circuit_layer_of_one_q_gates(pspec, qubit_labels = qubit_labels, rand_state=rand_state)]).parallelize()
twoQ_layer = _cir.Circuit(sample_circuit_layer_by_edgegrab(pspec, qubit_labels=qubit_labels, two_q_gate_density=two_q_gate_density,
rand_state=rand_state)).parallelize()
circ.append_circuit_inplace(twoQ_layer)
circ.append_circuit_inplace(oneQ_layer)
circ.done_editing()
Expand Down