Support QuTiP's Hamiltonian

README.md

@@ -28,6 +28,7 @@ For optional dependencies:
 ```bash
 pip install qamomile[qiskit]  # For Qiskit integration
 pip install qamomile[quri-parts]  # For QuriParts integration
+pip install qamomile[qutip]  # For QuTiP integration
 ```
 
 ## Quick Start

pyproject.toml

@@ -24,6 +24,7 @@ black = "^24.3.0"
 quri-parts-circuit = "^0.19.0"
 qiskit = "^1.1.1"
 matplotlib = "^3.9.2"
+qutip = "^5.0.4"
 
 
 [tool.poetry.group.dev.dependencies]
@@ -43,7 +44,7 @@ matplotlib = "^3.9.2"
 [tool.poetry.extras]
 qiskit = ["qiskit"]
 quri-parts = ["quri-parts-qulacs"]
-
+qutip = ["qutip"]
 
 [tool.pytest.ini_options]
 addopts = "--doctest-modules"

qamomile/qutip/__init__.py

@@ -0,0 +1,7 @@
+from qamomile.qutip.transpiler import QuTiPTranspiler
+from qamomile.qutip.exceptions import QamomileQuTiPTranspileError
+
+__all__ = [
+    "QuTiPTranspiler",
+    "QamomileQuTiPTranspileError"
+]

qamomile/qutip/exceptions.py

@@ -0,0 +1,4 @@
+class QamomileQuTiPTranspileError(Exception):
+    """Exception raised for errors in the Qamomile to QuTiP conversion process."""
+
+    pass

qamomile/qutip/transpiler.py

@@ -0,0 +1,76 @@
+"""
+Qamomile to QuTiP Transpiler Module
+
+This module provides functionality to convert Qamomile hamiltonians to their QuTiP equivalents. It includes a QuTiPTranspiler
+class that implements the QuantumSDKTranspiler interface for QuTiP compatibility.
+
+Key features:
+- Convert Qamomile Hamiltonians to QuTip Hamiltonians
+
+Usage:
+    from qamomile.qutip.transpiler import QuTiPTranspiler
+
+    transpiler = QuTiPTranspiler()
+    qp_operator = transpiler.transpile_hamiltonian(qamomile_hamiltonian)
+
+
+Note: This module requires both Qamomile and QuTiP to be installed.
+"""
+
+import qamomile.core.operator as qm_o
+
+import collections
+from qamomile.core.transpiler import QuantumSDKTranspiler
+from qutip import Qobj, sigmaz, sigmax, sigmay, tensor, qzero, qeye
+
+class QuTiPTranspiler(
+    QuantumSDKTranspiler[tuple[collections.Counter[int], int]]
+):
+    """
+    Transpiler class for converting between Qamomile and QuTiP quantum objects.
+
+    This class implements the QuantumSDKTranspiler interface for QuTiP compatibility,
+    providing methods to convert Hamiltonians.
+    """
+
+    def transpile_hamiltonian(
+        self,
+        operator: qm_o.Hamiltonian
+    ) -> Qobj:
+        """
+        Convert a Qamomile Hamiltonian to a QuTiP Hamiltonian.
+
+        Args:
+            operator (qm_o.Hamiltonian): The Qamomile Hamiltonian to convert.
+
+        Returns:
+            Qobj: The converted Hamiltonian.
+
+        Raises:
+            NotImplementedError: If an unsupported Pauli operator is encountered.
+        """
+        n = operator.num_qubits
+        H = tensor([qzero(2)]*n)
+        for term, coeff in operator.terms.items():
+            op_list = [qeye(2)] * n
+            for pauli in term:
+                match pauli.pauli:
+                    case qm_o.Pauli.X:
+                        op_list[pauli.index] = sigmax()
+                    case qm_o.Pauli.Y:
+                        op_list[pauli.index] = sigmay()
+                    case qm_o.Pauli.Z:
+                        op_list[pauli.index] = sigmaz()
+                    case _:
+                        raise NotImplementedError("Only Pauli X, Y, and Z are supported")
+            H += coeff* tensor(op_list)
+        return Qobj(H)
+
+    def transpile_circuit(
+        self
+    ) -> None:
+        pass
+    def convert_result(
+        self
+    ) -> None:
+        pass

tests/qutip/test_qutip_transpiler.py

@@ -0,0 +1,22 @@
+import pytest
+import qamomile.core.operator as qm_o
+from qamomile.qutip.transpiler import QuTiPTranspiler
+from qutip import Qobj, sigmaz, sigmax, sigmay, tensor
+
+@pytest.fixture
+def transpiler():
+    return QuTiPTranspiler()
+
+def test_transpile_hamiltonian(transpiler):
+    hamiltonian = qm_o.Hamiltonian()
+    hamiltonian += qm_o.X(0) * qm_o.Z(1)
+    qutip_hamiltonian = transpiler.transpile_hamiltonian(hamiltonian)
+
+    assert isinstance(qutip_hamiltonian, Qobj)
+    assert qutip_hamiltonian.shape == (2**hamiltonian.num_qubits, 2**hamiltonian.num_qubits)
+
+    hamiltonian2 = qm_o.Hamiltonian()
+    hamiltonian2 += qm_o.X(0) * qm_o.Y(1) + qm_o.Z(0) * qm_o.X(1)
+    qutip_hamiltonian2 = transpiler.transpile_hamiltonian(hamiltonian2)
+    H = tensor([sigmax(),sigmay()]) + tensor([sigmaz(),sigmax()])
+    assert H == qutip_hamiltonian2