diff --git a/src/circuit/qasm3_exporter.hpp b/src/circuit/qasm3_exporter.hpp
new file mode 100644
index 0000000..f8e9ff9
--- /dev/null
+++ b/src/circuit/qasm3_exporter.hpp
@@ -0,0 +1,479 @@
+/*
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2026.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+*/
+
+#ifndef __qiskitcpp_circuit_qasm3_exporter_hpp__
+#define __qiskitcpp_circuit_qasm3_exporter_hpp__
+
+#include "circuit/quantumcircuit_def.hpp"
+#include <algorithm>
+#include <cassert>
+#include <cstring>
+#include <iomanip>
+#include <iterator>
+#include <set>
+#include <sstream>
+#include <string>
+
+
+namespace Qiskit {
+namespace circuit {
+inline std::string to_qasm3(circuit::QuantumCircuit &circ)
+{
+    auto rust_circ = circ.get_rust_circuit(true);
+
+    std::stringstream qasm3;
+    qasm3 << std::setprecision(18);
+    qasm3 << "OPENQASM 3.0;" << std::endl;
+    qasm3 << "include \"stdgates.inc\";" << std::endl;
+    auto name_map = get_standard_gate_name_mapping();
+
+    // Input parameter declarations
+    uint_t num_params = circ.num_parameters();
+    if (num_params > 0)
+    {
+        std::set<std::string> symbol_names;
+        uint_t param_insts = qk_circuit_num_instructions(rust_circ.get());
+
+        for (uint_t i = 0; i < param_insts; i++)
+        {
+            QkCircuitInstruction inst;
+            qk_circuit_get_instruction(rust_circ.get(), i, &inst);
+
+            for (uint_t j = 0; j < inst.num_params; j++)
+            {
+                char *param_str = qk_param_str(inst.params[j]);
+                std::string s(param_str);
+                qk_str_free(param_str);
+
+                // Extract all identifier tokens from the param string.
+                static const std::set<std::string> reserved = {
+                    "sin", "cos", "tan", "asin", "acos", "atan", "exp", "log",
+                    "abs", "sign", "conjugate", "pi", "sqrt", "ceil", "floor"};
+
+                size_t pos = 0;
+                while (pos < s.size())
+                {
+                    const char c = s[pos];
+                    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_')
+                    {
+                        const size_t start = pos++;
+                        while (pos < s.size() &&
+                               ((s[pos] >= 'a' && s[pos] <= 'z') ||
+                                (s[pos] >= 'A' && s[pos] <= 'Z') ||
+                                (s[pos] >= '0' && s[pos] <= '9') || s[pos] == '_'))
+                        {
+                            pos++;
+                        }
+                        const std::string token = s.substr(start, pos - start);
+                        if (reserved.find(token) == reserved.end())
+                        {
+                            symbol_names.insert(token);
+                        }
+                        continue;
+                    }
+                    pos++;
+                }
+            }
+            qk_circuit_instruction_clear(&inst);
+        }
+
+        for (const auto &sym : symbol_names)
+        {
+            qasm3 << "input float[64] " << sym << ";" << std::endl;
+        }
+    }
+
+    // add header for non-standard gates
+    bool cs = false;
+    bool sxdg = false;
+    QkOpCounts opcounts = qk_circuit_count_ops(rust_circ.get());
+    for (int i = 0; i < opcounts.len; i++)
+    {
+        if (opcounts.data[i].count != 0)
+        {
+            auto op = name_map[opcounts.data[i].name].gate_map();
+            switch (op)
+            {
+            case QkGate_R:
+                qasm3 << "gate r(p0, p1) _gate_q_0 {" << std::endl;
+                qasm3 << "  U(p0, -pi/2 + p1, pi/2 - p1) _gate_q_0;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_SXdg:
+            case QkGate_RYY:
+            case QkGate_XXPlusYY:
+            case QkGate_XXMinusYY:
+                if (!sxdg)
+                {
+                    qasm3 << "gate sxdg _gate_q_0 {" << std::endl;
+                    qasm3 << "  s _gate_q_0;" << std::endl;
+                    qasm3 << "  h _gate_q_0;" << std::endl;
+                    qasm3 << "  s _gate_q_0;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                    sxdg = true;
+                }
+                if (op == QkGate_RYY)
+                {
+                    qasm3 << "gate ryy(p0) _gate_q_0, _gate_q_1 {" << std::endl;
+                    qasm3 << "  sxdg _gate_q_0;" << std::endl;
+                    qasm3 << "  sxdg _gate_q_1;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  sx _gate_q_0;" << std::endl;
+                    qasm3 << "  sx _gate_q_1;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                }
+                if (op == QkGate_XXPlusYY)
+                {
+                    qasm3 << "gate xx_plus_yy(p0, p1) _gate_q_0, _gate_q_1 {"
+                          << std::endl;
+                    qasm3 << "  rz(p1) _gate_q_0;" << std::endl;
+                    qasm3 << "  sdg _gate_q_1;" << std::endl;
+                    qasm3 << "  sx _gate_q_1;" << std::endl;
+                    qasm3 << "  s _gate_q_1;" << std::endl;
+                    qasm3 << "  s _gate_q_0;" << std::endl;
+                    qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
+                    qasm3 << "  ry((-0.5)*p0) _gate_q_1;" << std::endl;
+                    qasm3 << "  ry((-0.5)*p0) _gate_q_0;" << std::endl;
+                    qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
+                    qasm3 << "  sdg _gate_q_0;" << std::endl;
+                    qasm3 << "  sdg _gate_q_1;" << std::endl;
+                    qasm3 << "  sxdg _gate_q_1;" << std::endl;
+                    qasm3 << "  s _gate_q_1;" << std::endl;
+                    qasm3 << "  rz(-p1) _gate_q_0;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                }
+                if (op == QkGate_XXMinusYY)
+                {
+                    qasm3 << "gate xx_minus_yy(p0, p1) _gate_q_0, _gate_q_1 {"
+                          << std::endl;
+                    qasm3 << "  rz(-p1) _gate_q_1;" << std::endl;
+                    qasm3 << "  sdg _gate_q_0;" << std::endl;
+                    qasm3 << "  sx _gate_q_0;" << std::endl;
+                    qasm3 << "  s _gate_q_0;" << std::endl;
+                    qasm3 << "  s _gate_q_1;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  ry(0.5*p0) _gate_q_0;" << std::endl;
+                    qasm3 << "  ry((-0.5)*p0) _gate_q_1;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  sdg _gate_q_1;" << std::endl;
+                    qasm3 << "  sdg _gate_q_0;" << std::endl;
+                    qasm3 << "  sxdg _gate_q_0;" << std::endl;
+                    qasm3 << "  s _gate_q_0;" << std::endl;
+                    qasm3 << "  rz(p1) _gate_q_1;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                }
+                break;
+            case QkGate_DCX:
+                qasm3 << "gate dcx _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_ECR:
+                qasm3 << "gate ecr _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  s _gate_q_0;" << std::endl;
+                qasm3 << "  sx _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  x _gate_q_0;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_ISwap:
+                qasm3 << "gate iswap _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  s _gate_q_0;" << std::endl;
+                qasm3 << "  s _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_0;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
+                qasm3 << "  h _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_CSX:
+            case QkGate_CS:
+                if (!cs)
+                {
+                    qasm3 << "gate cs _gate_q_0, _gate_q_1 {" << std::endl;
+                    qasm3 << "  t _gate_q_0;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  tdg _gate_q_1;" << std::endl;
+                    qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  t _gate_q_1;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                    cs = true;
+                }
+                if (op == QkGate_CSX)
+                {
+                    qasm3 << "gate csx _gate_q_0, _gate_q_1 {" << std::endl;
+                    qasm3 << "  h _gate_q_1;" << std::endl;
+                    qasm3 << "  cs _gate_q_0, _gate_q_1;" << std::endl;
+                    qasm3 << "  h _gate_q_1;" << std::endl;
+                    qasm3 << "}" << std::endl;
+                }
+                break;
+            case QkGate_CSdg:
+                qasm3 << "gate csdg _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  tdg _gate_q_0;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  t _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  tdg _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_CCZ:
+                qasm3 << "gate ccz _gate_q_0, _gate_q_1, _gate_q_2 {" << std::endl;
+                qasm3 << "  h _gate_q_2;" << std::endl;
+                qasm3 << "  ccx _gate_q_0, _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_2;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_RXX:
+                qasm3 << "gate rxx(p0) _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  h _gate_q_0;" << std::endl;
+                qasm3 << "  h _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_0;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_RZX:
+                qasm3 << "gate rzx(p0) _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  h _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_RZZ:
+                qasm3 << "gate rzz(p0) _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_RCCX:
+                qasm3 << "gate rccx _gate_q_0, _gate_q_1, _gate_q_2 {" << std::endl;
+                qasm3 << "  h _gate_q_2;" << std::endl;
+                qasm3 << "  t _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  tdg _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
+                qasm3 << "  t _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  tdg _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_2;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_C3X:
+                qasm3 << "gate mcx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {"
+                      << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_0;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_1;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_2;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_C3SX:
+                qasm3 << "gate c3sx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {"
+                      << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(pi/8) _gate_q_0, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(-pi/8) _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(pi/8) _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(-pi/8) _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(pi/8) _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(-pi/8) _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cp(pi/8) _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_RC3X:
+                qasm3 << "gate rcccx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {"
+                      << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  t _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  tdg _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
+                qasm3 << "  t _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  tdg _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
+                qasm3 << "  t _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
+                qasm3 << "  tdg _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "  t _gate_q_3;" << std::endl;
+                qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
+                qasm3 << "  tdg _gate_q_3;" << std::endl;
+                qasm3 << "  h _gate_q_3;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_CU1:
+                qasm3 << "gate cu1(p0) _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  cp(p0) _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            case QkGate_CU3:
+                qasm3 << "gate cu3(p0, p1, p2) _gate_q_0, _gate_q_1 {" << std::endl;
+                qasm3 << "  cu(p0, p1, p2, 0) _gate_q_0, _gate_q_1;" << std::endl;
+                qasm3 << "}" << std::endl;
+                break;
+            default:
+                break;
+            }
+        }
+    }
+    qk_opcounts_clear(&opcounts);
+
+    // save ops
+    uint_t nops;
+    nops = qk_circuit_num_instructions(rust_circ.get());
+
+    // Declare registers
+    // After transpilation, qubit registers will be mapped to physical registers,
+    // so we need to combined them in a single quantum register "q";
+    const std::string qreg_name = "q";
+    qasm3 << "qubit[" << circ.num_qubits() << "] " << qreg_name << ";"
+          << std::endl;
+
+    const auto &cregs = circ.cregs();
+    for (const auto &creg : cregs)
+    {
+        qasm3 << "bit[" << creg.size() << "] " << creg.name() << ";" << std::endl;
+    }
+
+    auto recover_reg_data =
+        [&cregs](uint_t index) -> std::pair<std::string, uint_t>
+    {
+        auto it = std::upper_bound(cregs.begin(), cregs.end(), index,
+                                   [](uint_t v, const ClassicalRegister &reg)
+                                   {
+                                       return v < reg.base_index();
+                                   });
+        assert(it != cregs.begin());
+        it = std::prev(it);
+        return std::make_pair(it->name(), index - it->base_index());
+    };
+
+    for (uint_t i = 0; i < nops; i++)
+    {
+        QkCircuitInstruction *op = new QkCircuitInstruction;
+        qk_circuit_get_instruction(rust_circ.get(), i, op);
+        if (op->num_clbits > 0)
+        {
+            if (op->num_qubits == op->num_clbits)
+            {
+                for (uint_t j = 0; j < op->num_qubits; j++)
+                {
+                    const auto creg_data = recover_reg_data(op->clbits[j]);
+                    qasm3 << creg_data.first << "[" << creg_data.second
+                          << "] = " << op->name << " " << qreg_name << "["
+                          << op->qubits[j] << "];" << std::endl;
+                }
+            }
+        }
+        else
+        {
+            if (strcmp(op->name, "u") == 0)
+            {
+                qasm3 << "U";
+            }
+            else
+            {
+                qasm3 << op->name;
+            }
+            if (op->num_params > 0)
+            {
+                qasm3 << "(";
+                for (uint_t j = 0; j < op->num_params; j++)
+                {
+                    char *param = qk_param_str(op->params[j]);
+                    qasm3 << param;
+                    qk_str_free(param);
+                    if (j != op->num_params - 1)
+                        qasm3 << ", ";
+                }
+                qasm3 << ")";
+            }
+            if (op->num_qubits > 0)
+            {
+                qasm3 << " ";
+                for (uint_t j = 0; j < op->num_qubits; j++)
+                {
+                    qasm3 << qreg_name << "[" << op->qubits[j] << "]";
+                    if (j != op->num_qubits - 1)
+                        qasm3 << ", ";
+                }
+            }
+            qasm3 << ";" << std::endl;
+        }
+        qk_circuit_instruction_clear(op);
+    }
+
+    return qasm3.str();
+}
+}
+}
+
+#endif  // __qiskitcpp_circuit_qasm3_exporter_hpp__
\ No newline at end of file
diff --git a/src/circuit/quantumcircuit_def.hpp b/src/circuit/quantumcircuit_def.hpp
index d8add04..635fe98 100644
--- a/src/circuit/quantumcircuit_def.hpp
+++ b/src/circuit/quantumcircuit_def.hpp
@@ -1539,365 +1539,7 @@ class QuantumCircuit
 
 	/// @brief Serialize a QuantumCircuit object as an OpenQASM3 string.
 	/// @return An OpenQASM3 string.
-	std::string to_qasm3(void)
-	{
-		add_pending_control_flow_op();
-
-		std::stringstream qasm3;
-		qasm3 << std::setprecision(18);
-		qasm3 << "OPENQASM 3.0;" << std::endl;
-		qasm3 << "include \"stdgates.inc\";" << std::endl;
-
-		auto name_map = get_standard_gate_name_mapping();
-		// add header for non-standard gates
-		bool cs = false;
-		bool sxdg = false;
-		QkOpCounts opcounts = qk_circuit_count_ops(rust_circuit_.get());
-		for (int i = 0; i < opcounts.len; i++) {
-			if (opcounts.data[i].count != 0) {
-				auto op = name_map[opcounts.data[i].name].gate_map();
-				switch (op)
-				{
-				case QkGate_R:
-					qasm3 << "gate r(p0, p1) _gate_q_0 {" << std::endl;
-					qasm3 << "  U(p0, -pi/2 + p1, pi/2 - p1) _gate_q_0;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_SXdg:
-				case QkGate_RYY:
-				case QkGate_XXPlusYY:
-				case QkGate_XXMinusYY:
-					if (!sxdg)
-					{
-						qasm3 << "gate sxdg _gate_q_0 {" << std::endl;
-						qasm3 << "  s _gate_q_0;" << std::endl;
-						qasm3 << "  h _gate_q_0;" << std::endl;
-						qasm3 << "  s _gate_q_0;" << std::endl;
-						qasm3 << "}" << std::endl;
-						sxdg = true;
-					}
-					if (op == QkGate_RYY)
-					{
-						qasm3 << "gate ryy(p0) _gate_q_0, _gate_q_1 {" << std::endl;
-						qasm3 << "  sxdg _gate_q_0;" << std::endl;
-						qasm3 << "  sxdg _gate_q_1;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  sx _gate_q_0;" << std::endl;
-						qasm3 << "  sx _gate_q_1;" << std::endl;
-						qasm3 << "}" << std::endl;
-					}
-					if (op == QkGate_XXPlusYY)
-					{
-						qasm3 << "gate xx_plus_yy(p0, p1) _gate_q_0, _gate_q_1 {" << std::endl;
-						qasm3 << "  rz(p1) _gate_q_0;" << std::endl;
-						qasm3 << "  sdg _gate_q_1;" << std::endl;
-						qasm3 << "  sx _gate_q_1;" << std::endl;
-						qasm3 << "  s _gate_q_1;" << std::endl;
-						qasm3 << "  s _gate_q_0;" << std::endl;
-						qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
-						qasm3 << "  ry((-0.5)*p0) _gate_q_1;" << std::endl;
-						qasm3 << "  ry((-0.5)*p0) _gate_q_0;" << std::endl;
-						qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
-						qasm3 << "  sdg _gate_q_0;" << std::endl;
-						qasm3 << "  sdg _gate_q_1;" << std::endl;
-						qasm3 << "  sxdg _gate_q_1;" << std::endl;
-						qasm3 << "  s _gate_q_1;" << std::endl;
-						qasm3 << "  rz(-p1) _gate_q_0;" << std::endl;
-						qasm3 << "}" << std::endl;
-					}
-					if (op == QkGate_XXMinusYY)
-					{
-						qasm3 << "gate xx_minus_yy(p0, p1) _gate_q_0, _gate_q_1 {" << std::endl;
-						qasm3 << "  rz(-p1) _gate_q_1;" << std::endl;
-						qasm3 << "  sdg _gate_q_0;" << std::endl;
-						qasm3 << "  sx _gate_q_0;" << std::endl;
-						qasm3 << "  s _gate_q_0;" << std::endl;
-						qasm3 << "  s _gate_q_1;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  ry(0.5*p0) _gate_q_0;" << std::endl;
-						qasm3 << "  ry((-0.5)*p0) _gate_q_1;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  sdg _gate_q_1;" << std::endl;
-						qasm3 << "  sdg _gate_q_0;" << std::endl;
-						qasm3 << "  sxdg _gate_q_0;" << std::endl;
-						qasm3 << "  s _gate_q_0;" << std::endl;
-						qasm3 << "  rz(p1) _gate_q_1;" << std::endl;
-						qasm3 << "}" << std::endl;
-					}
-					break;
-				case QkGate_DCX:
-					qasm3 << "gate dcx _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_ECR:
-					qasm3 << "gate ecr _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  s _gate_q_0;" << std::endl;
-					qasm3 << "  sx _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  x _gate_q_0;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_ISwap:
-					qasm3 << "gate iswap _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  s _gate_q_0;" << std::endl;
-					qasm3 << "  s _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_0;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_0;" << std::endl;
-					qasm3 << "  h _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_CSX:
-				case QkGate_CS:
-					if (!cs)
-					{
-						qasm3 << "gate cs _gate_q_0, _gate_q_1 {" << std::endl;
-						qasm3 << "  t _gate_q_0;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  tdg _gate_q_1;" << std::endl;
-						qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  t _gate_q_1;" << std::endl;
-						qasm3 << "}" << std::endl;
-						cs = true;
-					}
-					if (op == QkGate_CSX)
-					{
-						qasm3 << "gate csx _gate_q_0, _gate_q_1 {" << std::endl;
-						qasm3 << "  h _gate_q_1;" << std::endl;
-						qasm3 << "  cs _gate_q_0, _gate_q_1;" << std::endl;
-						qasm3 << "  h _gate_q_1;" << std::endl;
-						qasm3 << "}" << std::endl;
-					}
-					break;
-				case QkGate_CSdg:
-					qasm3 << "gate csdg _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  tdg _gate_q_0;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  t _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  tdg _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_CCZ:
-					qasm3 << "gate ccz _gate_q_0, _gate_q_1, _gate_q_2 {" << std::endl;
-					qasm3 << "  h _gate_q_2;" << std::endl;
-					qasm3 << "  ccx _gate_q_0, _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_2;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_RXX:
-					qasm3 << "gate rxx(p0) _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  h _gate_q_0;" << std::endl;
-					qasm3 << "  h _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_0;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_RZX:
-					qasm3 << "gate rzx(p0) _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  h _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_RZZ:
-					qasm3 << "gate rzz(p0) _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  rz(p0) _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_RCCX:
-					qasm3 << "gate rccx _gate_q_0, _gate_q_1, _gate_q_2 {" << std::endl;
-					qasm3 << "  h _gate_q_2;" << std::endl;
-					qasm3 << "  t _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  tdg _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
-					qasm3 << "  t _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  tdg _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_2;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_C3X:
-					qasm3 << "gate mcx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_0;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_1;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_2;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  p(pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  p(-pi/8) _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_C3SX:
-					qasm3 << "gate c3sx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(pi/8) _gate_q_0, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(-pi/8) _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_1;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(pi/8) _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(-pi/8) _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(pi/8) _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(-pi/8) _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_2;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cp(pi/8) _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_RC3X:
-					qasm3 << "gate rcccx _gate_q_0, _gate_q_1, _gate_q_2, _gate_q_3 {" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  t _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  tdg _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
-					qasm3 << "  t _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  tdg _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_0, _gate_q_3;" << std::endl;
-					qasm3 << "  t _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_1, _gate_q_3;" << std::endl;
-					qasm3 << "  tdg _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "  t _gate_q_3;" << std::endl;
-					qasm3 << "  cx _gate_q_2, _gate_q_3;" << std::endl;
-					qasm3 << "  tdg _gate_q_3;" << std::endl;
-					qasm3 << "  h _gate_q_3;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_CU1:
-					qasm3 << "gate cu1(p0) _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  cp(p0) _gate_q_0 _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				case QkGate_CU3:
-					qasm3 << "gate cu3(p0, p1, p2) _gate_q_0, _gate_q_1 {" << std::endl;
-					qasm3 << "  cu(p0, p1, p2, 0) _gate_q_0 _gate_q_1;" << std::endl;
-					qasm3 << "}" << std::endl;
-					break;
-				default:
-					break;
-				}
-			}
-		}
-		qk_opcounts_clear(&opcounts);
-
-		// save ops
-		uint_t nops;
-		nops = qk_circuit_num_instructions(rust_circuit_.get());
-
-		// Declare registers
-		// After transpilation, qubit registers will be mapped to physical registers,
-		// so we need to combined them in a single quantum register "q";
-		const std::string qreg_name = "q";
-		qasm3 << "qubit[" << num_qubits() << "] " << qreg_name << ";" << std::endl;
-		for(const auto& creg : cregs_) {
-			qasm3 << "bit[" << creg.size() << "] " << creg.name() << ";" << std::endl;
-		}
-
-		auto recover_reg_data = [this](uint_t index) -> std::pair<std::string, uint_t>
-		{
-			auto it = std::upper_bound(cregs_.begin(), cregs_.end(), index,
-					[](uint_t v, const ClassicalRegister& reg) { return v < reg.base_index(); });
-			assert(it != cregs_.begin());
-			it = std::prev(it);
-			return std::make_pair(it->name(), index - it->base_index());
-		};
-
-		for (uint_t i = 0; i < nops; i++) {
-			QkCircuitInstruction *op = new QkCircuitInstruction;
-			qk_circuit_get_instruction(rust_circuit_.get(), i, op);
-			if (op->num_clbits > 0) {
-				if (op->num_qubits == op->num_clbits) {
-					for (uint_t j = 0; j < op->num_qubits; j++) {
-						const auto creg_data = recover_reg_data(op->clbits[j]);
-						qasm3 << creg_data.first << "[" << creg_data.second << "] = " << op->name << " " << qreg_name << "[" << op->qubits[j] << "];" << std::endl;
-					}
-				}
-			} else {
-				if (strcmp(op->name, "u") == 0) {
-					qasm3 << "U";
-				} else {
-					qasm3 << op->name;
-				}
-				if (op->num_params > 0) {
-					qasm3 << "(";
-					for (uint_t j = 0; j < op->num_params; j++) {
-						char* param = qk_param_str(op->params[j]);
-						qasm3 << param;
-						qk_str_free(param);
-						if (j != op->num_params - 1)
-							qasm3 << ", ";
-					}
-					qasm3 << ")";
-				}
-				if (op->num_qubits > 0) {
-					qasm3 << " ";
-					for (uint_t j = 0; j < op->num_qubits; j++) {
-						qasm3 << qreg_name << "[" << op->qubits[j] << "]";
-						if (j != op->num_qubits - 1)
-							qasm3 << ", ";
-					}
-				}
-				qasm3 << ";" << std::endl;
-			}
-			qk_circuit_instruction_clear(op);
-		}
-
-		return qasm3.str();
-	}
+	std::string to_qasm3(void);
 
 	/// @brief print circuit (this is for debug)
 	void print(void) const
@@ -2058,4 +1700,4 @@ class QuantumCircuit
 } // namespace circuit
 } // namespace Qiskit
 
-#endif // __qiskitcpp_circuit_quantum_circuit_def_hpp__
+#endif // __qiskitcpp_circuit_quantum_circuit_def_hpp__
\ No newline at end of file
diff --git a/src/circuit/quantumcircuit_impl.hpp b/src/circuit/quantumcircuit_impl.hpp
index 2fc2022..7d6fbd4 100644
--- a/src/circuit/quantumcircuit_impl.hpp
+++ b/src/circuit/quantumcircuit_impl.hpp
@@ -28,7 +28,7 @@
 #include <cassert>
 
 #include "controlflow/__init__.hpp"
-
+#include "circuit/qasm3_exporter.hpp"
 namespace Qiskit {
 namespace circuit {
 
@@ -57,6 +57,10 @@ inline void QuantumCircuit::add_pending_control_flow_op(void)
 }
 
 
+inline std::string QuantumCircuit::to_qasm3(void)
+{
+    return to_qasm3(*this);
+}
 }
 }
 
diff --git a/test/test_circuit.cpp b/test/test_circuit.cpp
index eae4cd8..0b42d0a 100644
--- a/test/test_circuit.cpp
+++ b/test/test_circuit.cpp
@@ -612,7 +612,7 @@ static int test_compose(void) {
     return Ok;
 }
 
-static int test_to_qasm3_multi_regs(void) {
+static int test_to_qasm3(void) {
     auto qreg1 = QuantumRegister(2, std::string("q1"));
     auto qreg2 = QuantumRegister(1, std::string("q2"));
     auto creg1 = ClassicalRegister(2, std::string("c1"));
@@ -641,6 +641,83 @@ static int test_to_qasm3_multi_regs(void) {
     return Ok;
 }
 
+static int test_to_qasm3_single_param(void) {
+    auto circ = QuantumCircuit(1, 0);
+    Parameter theta("theta");
+    circ.rx(theta, 0);
+
+    const auto actual = circ.to_qasm3();
+    const std::string expected = "OPENQASM 3.0;\n"
+                                "include \"stdgates.inc\";\n"
+                                "input float[64] theta;\n"
+                                "qubit[1] q;\n"
+                                "rx(theta) q[0];\n";
+    if (actual != expected) {
+        std::cerr << "  to_qasm3_single_param test : \n    expected:\n"
+                << expected << "\n    actual:\n"
+                << actual << std::endl;
+        return EqualityError;
+    }
+    return Ok;
+}
+
+static int test_to_qasm3_multiple_params(void) {
+    auto circ = QuantumCircuit(2, 0);
+    Parameter alpha("alpha");
+    Parameter beta("beta");
+    circ.rx(alpha, 0);
+    circ.ry(beta, 1);
+
+    const auto actual = circ.to_qasm3();
+    const std::string expected = "OPENQASM 3.0;\n"
+                                "include \"stdgates.inc\";\n"
+                                "input float[64] alpha;\n"
+                                "input float[64] beta;\n"
+                                "qubit[2] q;\n"
+                                "rx(alpha) q[0];\n"
+                                "ry(beta) q[1];\n";
+    if (actual != expected) {
+        std::cerr << "  to_qasm3_multiple_params test : \n    expected:\n"
+                << expected << "\n    actual:\n"
+                << actual << std::endl;
+        return EqualityError;
+    }
+    return Ok;
+}
+
+static int test_to_qasm3_expression_param(void) {
+    auto circ = QuantumCircuit(1, 0);
+    Parameter t("t");
+    Parameter expr = t + Parameter(0.5);
+    circ.rz(expr, 0);
+
+    const auto actual = circ.to_qasm3();
+    // The expression "0.5 + t" (or "t + 0.5") should cause only "t" to be
+    // declared as input, not the numeric literal.
+    if (actual.find("input float[64] t;") == std::string::npos) {
+        std::cerr
+            << "  to_qasm3_expression_param test : missing 'input float[64] t;'\n"
+            << "    actual:\n"
+            << actual << std::endl;
+        return EqualityError;
+    }
+
+    size_t count = 0;
+    size_t pos = 0;
+    while ((pos = actual.find("input float[64]", pos)) != std::string::npos) {
+        count++;
+        pos += 15;
+    }
+    if (count != 1) {
+        std::cerr << "  to_qasm3_expression_param test : expected 1 input "
+                     "declaration, got "
+                  << count << "\n    actual:\n"
+                << actual << std::endl;
+        return EqualityError;
+    }
+    return Ok;
+}
+
 #if defined(_WIN32)
 int test_circuit(int argc, char** const argv) {
 #else
@@ -651,7 +728,10 @@ int test_circuit(int argc, char** argv) {
     num_failed += RUN_TEST(test_measure);
     num_failed += RUN_TEST(test_append);
     num_failed += RUN_TEST(test_compose);
-    num_failed += RUN_TEST(test_to_qasm3_multi_regs);
+    num_failed += RUN_TEST(test_to_qasm3);
+    num_failed += RUN_TEST(test_to_qasm3_single_param);
+    num_failed += RUN_TEST(test_to_qasm3_multiple_params);
+    num_failed += RUN_TEST(test_to_qasm3_expression_param);
 
     std::cerr << "=== Number of failed subtests: " << num_failed << std::endl;
     return num_failed;