Skip to content

Apply two-qubit gate noise to every pair of a batched command #808

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
ciaranra merged 2 commits into from
Sep 21, 2026
Merged

Apply two-qubit gate noise to every pair of a batched command #808

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c6f5c29
Apply two-qubit gate noise to every pair of a batched command and jud…
ciaranra Sep 20, 2026
2d7eef8
Merge branch 'dev' into noise-batched-two-qubit-pairs
ciaranra Sep 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
235 changes: 146 additions & 89 deletions crates/pecos-engines/src/noise/biased_depolarizing.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -352,97 +352,103 @@ impl BiasedDepolarizingNoiseModel {
}

fn apply_tq_faults(&mut self, builder: &mut ByteMessageBuilder, gate: &Gate) {
if self.rng.occurs(self.p2) {
let fault_type = self.rng.random_int(0..15);
let qubit0 = gate.qubits[0];
let qubit1 = gate.qubits[1];

match fault_type {
// IX
0 => {
trace!("Applying IX fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_x(builder, *qubit1);
}
// IY
1 => {
trace!("Applying IY fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_y(builder, *qubit1);
}
// IZ
2 => {
trace!("Applying IZ fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_z(builder, *qubit1);
}
// XI
3 => {
trace!("Applying XI fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_x(builder, *qubit0);
}
// XX
4 => {
trace!("Applying XX fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// XY
5 => {
trace!("Applying XY fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// XZ
6 => {
trace!("Applying XZ fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
}
// YI
7 => {
trace!("Applying YI fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_y(builder, *qubit0);
}
// YX
8 => {
trace!("Applying YX fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// YY
9 => {
trace!("Applying YY fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// YZ
10 => {
trace!("Applying YZ fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
}
// ZI
11 => {
trace!("Applying ZI fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_z(builder, *qubit0);
}
// ZX
12 => {
trace!("Applying ZX fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// ZY
13 => {
trace!("Applying ZY fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// ZZ
_ => {
trace!("Applying ZZ fault on qubits {:?}", gate.qubits);
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
// CCX retains its existing first-two-qubits fault behavior.
for qubits in gate.qubits.as_chunks::<2>().0 {
if self.rng.occurs(self.p2) {
let fault_type = self.rng.random_int(0..15);
let qubit0 = qubits[0];
let qubit1 = qubits[1];

match fault_type {
// IX
0 => {
trace!("Applying IX fault on qubits {qubits:?}");
NoiseUtils::apply_x(builder, *qubit1);
}
// IY
1 => {
trace!("Applying IY fault on qubits {qubits:?}");
NoiseUtils::apply_y(builder, *qubit1);
}
// IZ
2 => {
trace!("Applying IZ fault on qubits {qubits:?}");
NoiseUtils::apply_z(builder, *qubit1);
}
// XI
3 => {
trace!("Applying XI fault on qubits {qubits:?}");
NoiseUtils::apply_x(builder, *qubit0);
}
// XX
4 => {
trace!("Applying XX fault on qubits {qubits:?}");
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// XY
5 => {
trace!("Applying XY fault on qubits {qubits:?}");
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// XZ
6 => {
trace!("Applying XZ fault on qubits {qubits:?}");
NoiseUtils::apply_x(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
}
// YI
7 => {
trace!("Applying YI fault on qubits {qubits:?}");
NoiseUtils::apply_y(builder, *qubit0);
}
// YX
8 => {
trace!("Applying YX fault on qubits {qubits:?}");
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// YY
9 => {
trace!("Applying YY fault on qubits {qubits:?}");
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// YZ
10 => {
trace!("Applying YZ fault on qubits {qubits:?}");
NoiseUtils::apply_y(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
}
// ZI
11 => {
trace!("Applying ZI fault on qubits {qubits:?}");
NoiseUtils::apply_z(builder, *qubit0);
}
// ZX
12 => {
trace!("Applying ZX fault on qubits {qubits:?}");
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_x(builder, *qubit1);
}
// ZY
13 => {
trace!("Applying ZY fault on qubits {qubits:?}");
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_y(builder, *qubit1);
}
// ZZ
_ => {
trace!("Applying ZZ fault on qubits {qubits:?}");
NoiseUtils::apply_z(builder, *qubit0);
NoiseUtils::apply_z(builder, *qubit1);
}
}
}
if gate.gate_type == GateType::CCX {
break;
}
}
}
}
Expand Down Expand Up @@ -658,6 +664,57 @@ impl crate::noise::IntoNoiseModel for BiasedDepolarizingNoiseModelBuilder {
mod tests {
use super::*;

#[test]
fn test_ccx_faults_retain_first_pair_behavior() {
for seed in 0..16 {
for triples in [vec![(0, 1, 2)], vec![(0, 1, 2), (3, 4, 5)]] {
let mut noise = BiasedDepolarizingNoiseModel::new(0.0, 0.0, 0.0, 0.0, 1.0);
noise.set_seed(seed);
let mut reference = noise.clone();
let mut ccx = ByteMessage::quantum_operations_builder();
ccx.add_gate_command(&Gate::ccx(&triples));
ccx.cx(&[(6, 7)]);
let mut cx = ByteMessage::quantum_operations_builder();
cx.cx(&[(0, 1)]);
cx.cx(&[(6, 7)]);
let EngineStage::NeedsProcessing(actual) = noise.start(ccx.build()).unwrap() else {
panic!("Expected NeedsProcessing stage");
};
let EngineStage::NeedsProcessing(expected) = reference.start(cx.build()).unwrap()
else {
panic!("Expected NeedsProcessing stage");
};
// The following CX also verifies that CCX consumed only one fault draw.
assert_eq!(
actual.quantum_ops().unwrap()[1..],
expected.quantum_ops().unwrap()[1..]
);
}
}
}

#[test]
fn test_batched_two_qubit_faults_are_independent() {
for seed in 0..32 {
let mut noise = BiasedDepolarizingNoiseModel::new(0.0, 0.0, 0.0, 0.0, 0.5);
noise.set_seed(seed);
let mut separate = noise.clone();
// Compare fault bytes: ideal gate serialization differs between batching forms.
let mut batched_output = ByteMessage::quantum_operations_builder();
noise.apply_tq_faults(&mut batched_output, &Gate::cx(&[(0, 1), (2, 3)]));
noise.apply_tq_faults(&mut batched_output, &Gate::cx(&[(4, 5)]));
let mut separate_output = ByteMessage::quantum_operations_builder();
for pair in [(0, 1), (2, 3), (4, 5)] {
separate.apply_tq_faults(&mut separate_output, &Gate::cx(&[pair]));
}
assert_eq!(
batched_output.build().as_bytes(),
separate_output.build().as_bytes(),
"batched fault stream differs at seed {seed}"
);
}
}

#[test]
fn test_probabilities_getter_and_setter() {
// Create a noise model with initial probabilities
Expand Down
Loading
Loading