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Remove duplicated method on TwoQubitBasisDecomposer #15835

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Merged
alexanderivrii merged 1 commit into from
Mar 23, 2026
Merged

Remove duplicated method on TwoQubitBasisDecomposer #15835

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102 changes: 4 additions & 98 deletions crates/synthesis/src/two_qubit_decompose/basis_decomposer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -713,100 +713,6 @@ impl TwoQubitBasisDecomposer {
global_phase,
})
}
/// Decompose a two-qubit ``unitary`` over fixed basis and :math:`SU(2)` using the best
/// approximation given that each basis application has a finite ``basis_fidelity``.
fn generate_sequence(
&self,
unitary: PyReadonlyArray2<Complex64>,
basis_fidelity: Option<f64>,
approximate: bool,
_num_basis_uses: Option<u8>,
) -> PyResult<TwoQubitGateSequence> {
let basis_fidelity = if !approximate {
1.0
} else {
basis_fidelity.unwrap_or(self.basis_fidelity)
};
let target_decomposed =
TwoQubitWeylDecomposition::new(unitary, Some(DEFAULT_FIDELITY), None)?;
let traces = self.traces(&target_decomposed);
let best_nbasis = traces
.into_iter()
.enumerate()
.map(|(idx, trace)| (idx, trace.trace_to_fid() * basis_fidelity.powi(idx as i32)))
.min_by(|(_idx1, fid1), (_idx2, fid2)| fid2.partial_cmp(fid1).unwrap())
.unwrap()
.0;
let best_nbasis = _num_basis_uses.unwrap_or(best_nbasis as u8);
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@alexanderivrii alexanderivrii Mar 23, 2026

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As far as I can tell, there is no real difference between the two functions, while the surviving function is more efficient handling this line - does not eagerly compute best_nbasis.

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@alexanderivrii alexanderivrii Mar 23, 2026

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Ah, Shelly has already approved the changes as well. :)

let decomposition = match best_nbasis {
0 => decomp0_inner(&target_decomposed),
1 => self.decomp1_inner(&target_decomposed),
2 => self.decomp2_supercontrolled_inner(&target_decomposed),
3 => self.decomp3_supercontrolled_inner(&target_decomposed),
_ => unreachable!("Invalid basis to use"),
};
let pulse_optimize = self.pulse_optimize.unwrap_or(true);
let sequence = if pulse_optimize {
self.pulse_optimal_chooser(best_nbasis, &decomposition, &target_decomposed)?
} else {
None
};
if let Some(seq) = sequence {
return Ok(seq);
}
let mut target_1q_basis_list = EulerBasisSet::new();
target_1q_basis_list.add_basis(self.euler_basis);
let euler_decompositions: SmallVec<[Option<OneQubitGateSequence>; 8]> = decomposition
.iter()
.map(|decomp| {
unitary_to_gate_sequence_inner(
decomp.view(),
&target_1q_basis_list,
0,
None,
true,
None,
)
})
.collect();
let mut gates = Vec::with_capacity(TWO_QUBIT_SEQUENCE_DEFAULT_CAPACITY);
let mut global_phase = target_decomposed.global_phase;
global_phase -= best_nbasis as f64 * self.basis_decomposer.global_phase;
if best_nbasis == 2 {
global_phase += PI;
}
for i in 0..best_nbasis as usize {
if let Some(euler_decomp) = &euler_decompositions[2 * i] {
for gate in &euler_decomp.gates {
gates.push((gate.0.into(), gate.1.clone(), smallvec![0]));
}
global_phase += euler_decomp.global_phase
}
if let Some(euler_decomp) = &euler_decompositions[2 * i + 1] {
for gate in &euler_decomp.gates {
gates.push((gate.0.into(), gate.1.clone(), smallvec![1]));
}
global_phase += euler_decomp.global_phase
}
gates.push((self.gate.clone(), self.gate_params.clone(), smallvec![0, 1]));
}
if let Some(euler_decomp) = &euler_decompositions[2 * best_nbasis as usize] {
for gate in &euler_decomp.gates {
gates.push((gate.0.into(), gate.1.clone(), smallvec![0]));
}
global_phase += euler_decomp.global_phase
}
if let Some(euler_decomp) = &euler_decompositions[2 * best_nbasis as usize + 1] {
for gate in &euler_decomp.gates {
gates.push((gate.0.into(), gate.1.clone(), smallvec![1]));
}
global_phase += euler_decomp.global_phase
}
Ok(TwoQubitGateSequence {
gates,
global_phase,
})
}
}

static K12R_ARR: GateArray1Q = [
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@ShellyGarion ShellyGarion Mar 23, 2026

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perhaps this should be moved to common?

Expand Down Expand Up @@ -993,8 +899,8 @@ impl TwoQubitBasisDecomposer {
approximate: bool,
_num_basis_uses: Option<u8>,
) -> PyResult<DAGCircuit> {
let sequence =
self.generate_sequence(unitary, basis_fidelity, approximate, _num_basis_uses)?;
let array = unitary.as_array();
let sequence = self.call_inner(array, basis_fidelity, approximate, _num_basis_uses)?;
let mut dag = DAGCircuit::with_capacity(2, 0, None, Some(sequence.gates.len()), None, None);
dag.set_global_phase_f64(sequence.global_phase);
dag.add_qubit_unchecked(ShareableQubit::new_anonymous())?;
Expand Down Expand Up @@ -1036,8 +942,8 @@ impl TwoQubitBasisDecomposer {
approximate: bool,
_num_basis_uses: Option<u8>,
) -> PyResult<PyCircuitData> {
let sequence =
self.generate_sequence(unitary, basis_fidelity, approximate, _num_basis_uses)?;
let array = unitary.as_array();
let sequence = self.call_inner(array, basis_fidelity, approximate, _num_basis_uses)?;
Ok(CircuitData::from_packed_operations(
2,
0,
Expand Down
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