preliminary framework for a backend quantum provider

src/qib/__init__.py

@@ -7,6 +7,7 @@
     algorithms,
     simulator,
     tensor_network,
+    backend,
     util
 )
 

src/qib/backend/__init__.py

@@ -0,0 +1,2 @@
+from qib.backend.quantum_provider        import QuantumProvider
+from qib.backend.tensor_network_provider import TensorNetworkProvider

src/qib/backend/quantum_provider.py

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+import abc
+from typing import Sequence
+from qib.circuit import Circuit
+from qib.field import Field
+
+
+class QuantumProvider(abc.ABC):
+
+    @abc.abstractmethod
+    def submit(self, circ: Circuit, fields: Sequence[Field], description):
+        """
+        Submit a quantum circuit to a backend provider,
+        returning a "job" object to query the results.
+        """
+        pass
+
+    @abc.abstractmethod
+    def query_results(self, job):
+        """
+        Query results of a previously submitted job.
+        """
+        pass

src/qib/backend/tensor_network_provider.py

@@ -0,0 +1,31 @@
+import h5py
+from typing import Sequence
+from qib.backend import QuantumProvider
+from qib.circuit import Circuit
+from qib.field import Field
+
+
+class TensorNetworkProvider(QuantumProvider):
+
+    def submit(self, circ: Circuit, fields: Sequence[Field], description):
+        """
+        Submit a quantum circuit to a backend provider,
+        returning a "job" object to query the results.
+        """
+        net = circ.as_tensornet(fields)
+        # store network in a HDF5 file
+        with h5py.File(description["filename"], "w") as f:
+            tgrp = f.create_group("tensors")
+            for tensor in net.net.tensors.values():
+                dset = tgrp.create_dataset(str(tensor.tid), data=() if tensor.tid == -1 else net.data[tensor.dataref].astype(complex))
+                dset.attrs["tid"] = tensor.tid
+                dset.attrs["bids"] = tensor.bids
+        job = { "net": net }
+        return job
+
+
+    def query_results(self, job):
+        """
+        Query results of a previously submitted job.
+        """
+        pass

tests/test_backend.py

@@ -0,0 +1,31 @@
+import numpy as np
+import unittest
+import qib
+
+
+class TestBackend(unittest.TestCase):
+
+    def test_tensor_network(self):
+        """
+        Test tensor network backend functionality.
+        """
+        field = qib.field.Field(qib.field.ParticleType.QUBIT, qib.lattice.IntegerLattice((2,)))
+        qa = qib.field.Qubit(field, 0)
+        qb = qib.field.Qubit(field, 1)
+        # Hadamard gate
+        hadamard = qib.HadamardGate(qa)
+        # CNOT gate
+        cnot = qib.ControlledGate(qib.PauliXGate(qb), 1).set_control(qa)
+        # construct a simple quantum circuit
+        circuit = qib.Circuit()
+        circuit.append_gate(hadamard)
+        circuit.append_gate(cnot)
+        self.assertTrue(circuit.fields() == [field])
+        h_cnot = cnot.as_matrix() @ np.kron(hadamard.as_matrix(), np.identity(2))
+        self.assertTrue(np.array_equal(circuit.as_matrix([field]).toarray(), h_cnot))
+        provider = qib.backend.TensorNetworkProvider()
+        provider.submit(circuit, [field], { "filename": "bell_circuit_tensornet.hdf5" })
+
+
+if __name__ == "__main__":
+    unittest.main()