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Merging conditionals
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@yao-cqc
yao-cqc committed Oct 10, 2024
1 parent 4fdfbec commit f5138f1
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Showing 2 changed files with 77 additions and 38 deletions.
75 changes: 52 additions & 23 deletions tket/src/Transformations/GreedyPauliOptimisation.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -309,19 +309,26 @@ static void tableau_row_nodes_synthesis(
* first set where the tqe_cost is zero. Remove implemented nodes and the first
* set if empty.
*
* @param rotation_sets
* @param node_sets
* @param circ
* @param depth_tracker
* @param discount_rate
* @param depth_weight
*
* @return true if the first set is now empty and removed
* @return false
*/
static void consume_nodes(
std::vector<std::vector<PauliNode_ptr>>& rotation_sets, Circuit& circ,
DepthTracker& depth_tracker) {
if (rotation_sets.empty()) {
std::vector<std::vector<PauliNode_ptr>>& node_sets, Circuit& circ,
DepthTracker& depth_tracker, double discount_rate, double depth_weight) {
if (node_sets.empty()) {
return;
}
while (true) {
std::vector<PauliNode_ptr>& first_set = rotation_sets[0];
std::vector<PauliNode_ptr>& first_set = node_sets[0];
// try to merge conditionals, and each conditioned circuits will be
// optimised recursively via greedy_pauli_graph_synthesis
std::map<std::pair<std::vector<unsigned>, unsigned>, Circuit> conditionals;
for (unsigned i = first_set.size(); i-- > 0;) {
PauliNode_ptr& node_ptr = first_set[i];
switch (node_ptr->get_type()) {
Expand Down Expand Up @@ -413,15 +420,24 @@ static void consume_nodes(
// conditionals are added as conditional PauliExpBoxes
ConditionalPauliRotation& node =
dynamic_cast<ConditionalPauliRotation&>(*node_ptr);
Op_ptr cond = std::make_shared<Conditional>(
std::make_shared<PauliExpBox>(
SymPauliTensor(node.string(), node.angle())),
(unsigned)node.cond_bits().size(), node.cond_value());
std::vector<unsigned> args = node.cond_bits();
const std::vector<unsigned> cond_bits = node.cond_bits();
const unsigned cond_value = node.cond_value();
std::vector<unsigned> qubits;
for (unsigned i = 0; i < node.string().size(); i++) {
args.push_back(i);
qubits.push_back(i);
}
Op_ptr peb_op = std::make_shared<PauliExpBox>(
SymPauliTensor(node.string(), node.angle()));

if (conditionals.find({cond_bits, cond_value}) ==
conditionals.end()) {
Circuit cond_circ(circ.n_qubits());
cond_circ.add_op<unsigned>(peb_op, qubits);
conditionals[{cond_bits, cond_value}] = cond_circ;
} else {
conditionals[{cond_bits, cond_value}].add_op<unsigned>(
peb_op, qubits);
}
circ.add_op<unsigned>(cond, args);
first_set.erase(first_set.begin() + i);
break;
}
Expand Down Expand Up @@ -456,9 +472,21 @@ static void consume_nodes(
TKET_ASSERT(false);
}
}
for (auto it = conditionals.begin(); it != conditionals.end(); it++) {
Circuit cond_circ =
greedy_pauli_graph_synthesis(it->second, discount_rate, depth_weight);
Op_ptr cond = std::make_shared<Conditional>(
std::make_shared<CircBox>(cond_circ), it->first.first.size(),
it->first.second);
std::vector<unsigned> args = it->first.first;
for (unsigned i = 0; i < cond_circ.n_qubits(); i++) {
args.push_back(i);
}
circ.add_op<unsigned>(cond, args);
}
if (first_set.empty()) {
rotation_sets.erase(rotation_sets.begin());
if (rotation_sets.empty()) {
node_sets.erase(node_sets.begin());
if (node_sets.empty()) {
return;
}
} else {
Expand All @@ -471,13 +499,13 @@ static void consume_nodes(
* @brief Synthesise a vector of unordered rotation sets
*/
static void pauli_exps_synthesis(
std::vector<std::vector<PauliNode_ptr>>& rotation_sets,
std::vector<std::vector<PauliNode_ptr>>& node_sets,
std::vector<PauliNode_ptr>& rows, Circuit& circ, double discount_rate,
double depth_weight, DepthTracker& depth_tracker) {
while (true) {
consume_nodes(rotation_sets, circ, depth_tracker);
if (rotation_sets.empty()) break;
std::vector<PauliNode_ptr>& first_set = rotation_sets[0];
consume_nodes(node_sets, circ, depth_tracker, discount_rate, depth_weight);
if (node_sets.empty()) break;
std::vector<PauliNode_ptr>& first_set = node_sets[0];
// get nodes with min cost
std::vector<unsigned> min_nodes_indices = {0};
unsigned min_cost = first_set[0]->tqe_cost();
Expand All @@ -501,7 +529,7 @@ static void pauli_exps_synthesis(
for (const TQE& tqe : tqe_candidates) {
tqe_candidates_cost.insert(
{tqe,
{default_pauliexp_tqe_cost(discount_rate, rotation_sets, rows, tqe),
{default_pauliexp_tqe_cost(discount_rate, node_sets, rows, tqe),
static_cast<double>(depth_tracker.gate_depth(
std::get<1>(tqe), std::get<2>(tqe)))}});
}
Expand All @@ -511,7 +539,7 @@ static void pauli_exps_synthesis(
apply_tqe_to_circ(selected_tqe, circ);
depth_tracker.add_2q_gate(
std::get<1>(selected_tqe), std::get<2>(selected_tqe));
for (std::vector<PauliNode_ptr>& rotation_set : rotation_sets) {
for (std::vector<PauliNode_ptr>& rotation_set : node_sets) {
for (PauliNode_ptr& node : rotation_set) {
node->update(selected_tqe);
}
Expand Down Expand Up @@ -557,12 +585,11 @@ Circuit greedy_pauli_graph_synthesis(
rev_unit_map.insert({pair.second, pair.first});
}
GPGraph gpg(circ_flat);
auto [rotation_sets, rows, measures] = gpg.get_sequence();
auto [node_sets, rows, measures] = gpg.get_sequence();
DepthTracker depth_tracker(n_qubits);
// synthesise Pauli exps
pauli_exps_synthesis(
rotation_sets, rows, new_circ, discount_rate, depth_weight,
depth_tracker);
node_sets, rows, new_circ, discount_rate, depth_weight, depth_tracker);
// synthesise the tableau
tableau_row_nodes_synthesis(rows, new_circ, depth_weight, depth_tracker);
for (auto it = measures.begin(); it != measures.end(); ++it) {
Expand All @@ -579,6 +606,8 @@ Transform greedy_pauli_optimisation(double discount_rate, double depth_weight) {
return Transform([discount_rate, depth_weight](Circuit& circ) {
circ = GreedyPauliSimp::greedy_pauli_graph_synthesis(
circ, discount_rate, depth_weight);
// decompose conditional circ boxes
circ.decompose_boxes_recursively();
singleq_clifford_sweep().apply(circ);
return true;
});
Expand Down
40 changes: 25 additions & 15 deletions tket/test/src/test_GreedyPauli.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -252,11 +252,8 @@ SCENARIO("Complete synthesis") {
circ.add_conditional_gate<unsigned>(OpType::Rz, {0.5}, {0}, {0}, 0);
circ.add_op<unsigned>(OpType::CX, {0, 1});
Circuit d(2, 2);
Op_ptr cond = std::make_shared<Conditional>(
std::make_shared<PauliExpBox>(
SymPauliTensor({Pauli::Z, Pauli::I}, 0.5)),
1, 0);
d.add_op<unsigned>(cond, {0, 0, 1});
d.add_conditional_gate<unsigned>(OpType::Sdg, {}, {0}, {0}, 0);
d.add_conditional_gate<unsigned>(OpType::Z, {}, {0}, {0}, 0);
REQUIRE(Transforms::greedy_pauli_optimisation().apply(circ));
REQUIRE(circ == d);
}
Expand All @@ -273,18 +270,13 @@ SCENARIO("Complete synthesis") {
Circuit d(2, 1);
d.add_op<unsigned>(OpType::CY, {1, 0});
d.add_op<unsigned>(OpType::Rx, 0.12, {0});
Op_ptr cond2 = std::make_shared<Conditional>(
std::make_shared<PauliExpBox>(
SymPauliTensor({Pauli::Z, Pauli::I}, 0.5)),
1, 0);
d.add_op<unsigned>(cond2, {0, 0, 1});
d.add_conditional_gate<unsigned>(OpType::Sdg, {}, {0}, {0}, 0);
d.add_conditional_gate<unsigned>(OpType::Z, {}, {0}, {0}, 0);
d.add_op<unsigned>(OpType::CY, {1, 0});
REQUIRE(Transforms::greedy_pauli_optimisation().apply(circ));
REQUIRE(circ == d);
}
GIVEN("Circuit with conditional gates and measures") {
PauliExpBox pb1(SymPauliTensor({Pauli::Z, Pauli::X}, 0.12));
PauliExpBox pb2(SymPauliTensor({Pauli::X, Pauli::Z}, 0.3));
Circuit circ(2, 2);
Op_ptr cond1 = std::make_shared<Conditional>(
std::make_shared<PauliExpBox>(
Expand All @@ -301,10 +293,28 @@ SCENARIO("Complete synthesis") {
// can commute to the front
circ.add_op<unsigned>(cond1, {1, 0, 1});
Circuit d(2, 2);
d.add_op<unsigned>(cond1, {0, 0, 1});
d.add_op<unsigned>(cond1, {1, 0, 1});
// ZZ 0.5
d.add_conditional_gate<unsigned>(OpType::CX, {}, {0, 1}, {0}, 0);
d.add_conditional_gate<unsigned>(OpType::Sdg, {}, {0}, {0}, 0);
d.add_conditional_gate<unsigned>(OpType::V, {}, {1}, {0}, 0);
d.add_conditional_gate<unsigned>(OpType::Z, {}, {0}, {0}, 0);
// ZZ 0.5 conditioned on bit(1)
d.add_conditional_gate<unsigned>(OpType::CX, {}, {0, 1}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::Sdg, {}, {0}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::V, {}, {1}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::Z, {}, {0}, {1}, 0);
d.add_op<unsigned>(OpType::Measure, {0, 0});
d.add_op<unsigned>(cond2, {1, 0, 1});
// XZ 0.25
// compute
d.add_conditional_gate<unsigned>(OpType::H, {}, {0}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::CX, {}, {0, 1}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::H, {}, {0}, {1}, 0);
// action
d.add_conditional_gate<unsigned>(OpType::Rz, {0.25}, {1}, {1}, 0);
// uncompute
d.add_conditional_gate<unsigned>(OpType::H, {}, {0}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::CX, {}, {0, 1}, {1}, 0);
d.add_conditional_gate<unsigned>(OpType::H, {}, {0}, {1}, 0);
REQUIRE(Transforms::greedy_pauli_optimisation().apply(circ));
REQUIRE(circ == d);
}
Expand Down

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