Merge pull request #13 from qiboteam/quimb-qasm-parser

Refactor quimb backend

.pre-commit-config.yaml

@@ -0,0 +1,25 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.4.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-toml
+      - id: check-merge-conflict
+      - id: debug-statements
+  - repo: https://github.com/psf/black
+    rev: 23.1.0
+    hooks:
+      - id: black
+  - repo: https://github.com/pycqa/isort
+    rev: 5.12.0
+    hooks:
+      - id: isort
+        args: ["--profile", "black"]
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v3.3.1
+    hooks:
+      - id: pyupgrade

src/qibotn/quimb.py

@@ -0,0 +1,39 @@
+import numpy as np
+import quimb.tensor as qtn
+from qibo.models import Circuit as QiboCircuit
+
+
+def from_qibo(circuit: QiboCircuit, psi0=None):
+    nqubits = circuit.nqubits
+    tncirc = qtn.Circuit(nqubits, psi0=psi0)
+
+    for gate in circuit.queue:
+        tncirc.apply_gate(
+            gate.name,
+            *gate.parameters,
+            *gate.qubits,
+            parametrize=len(gate.parameters) > 0
+        )
+
+    return tncirc
+
+
+def init_state_tn(nqubits, init_state_sv):
+    dims = tuple(2 * np.ones(nqubits, dtype=int))
+
+    return qtn.tensor_1d.MatrixProductState.from_dense(init_state_sv, dims)
+
+
+def eval(qasm: str, init_state, backend="numpy"):
+    """Evaluate QASM with Quimb
+
+    backend (quimb): numpy, cupy, jax. Passed to ``opt_einsum``.
+
+    """
+    circuit = QiboCircuit.from_qasm(qasm)
+    init_state_mps = init_state_tn(circuit.nqubits, init_state)
+    circ_quimb = from_qibo(circuit, psi0=init_state_mps)
+    interim = circ_quimb.psi.full_simplify(seq="DRC")
+    amplitudes = interim.to_dense(backend=backend).flatten()
+
+    return amplitudes

tests/config.py

@@ -1,10 +1,12 @@
-qibo = dict(
-    backend = 'qibojit',
-    platform = 'numpy',
-    swaps = True
-)
-
-quimb = dict(
-    backend = 'numpy',
-    swaps = True
-)
+from dataclasses import dataclass
+from typing import Optional
+
+
+@dataclass
+class Executor:
+    backend: str
+    platform: Optional[str] = None
+
+
+qibo = Executor(backend="qibojit", platform="numpy")
+quimb = Executor(backend="numpy")

tests/test_qasm_quimb_backend.py

@@ -1,22 +1,18 @@
+import copy
 import os
+from timeit import default_timer as timer
 
+import config
+import numpy as np
 import pytest
 import qibo
 from qibo.models import QFT
-import numpy as np
-import copy
-from timeit import default_timer as timer
-
-import config
 
 
-def init_state_sv(nqubits):
-    init_state = np.random.random(2**nqubits) + \
-        1j * np.random.random(2**nqubits)
+def create_init_state(nqubits):
+    init_state = np.random.random(2**nqubits) + 1j * np.random.random(2**nqubits)
     init_state = init_state / np.sqrt((np.abs(init_state) ** 2).sum())
-    # An unmodified init_state has to be converted to tn format
-    init_state_for_tn = copy.deepcopy(init_state)
-    return init_state, init_state_for_tn
+    return init_state
 
 
 def qibo_qft(nqubits, init_state, swaps):
@@ -25,33 +21,40 @@ def qibo_qft(nqubits, init_state, swaps):
     return circ_qibo, state_vec
 
 
+def time(func):
+    start = timer()
+    res = func()
+    end = timer()
+    time = end - start
+    return time, res
+
+
 @pytest.mark.parametrize("nqubits", [1, 2, 5, 10])
 def test_eval(nqubits: int):
+    # hack quimb to use the correct number of processes
+    # TODO: remove completely, or at least delegate to the backend
+    # implementation
     os.environ["QUIMB_NUM_PROCS"] = str(os.cpu_count())
-    from qibotn import qasm_quimb
+    import qibotn.quimb
 
-    init_state_qibo, init_state_for_tn = init_state_sv(nqubits=nqubits)
+    init_state = create_init_state(nqubits=nqubits)
+    init_state_tn = copy.deepcopy(init_state)
 
     # Test qibo
-    qibo.set_backend(backend=config.qibo['backend'],
-                     platform=config.qibo['platform'])
-    start_time = timer()
-    qibo_circ, result_sv = qibo_qft(nqubits, init_state=init_state_qibo,
-                                    swaps=config.qibo['swaps'])
-    end_time = timer()
-    qibo_time = end_time - start_time
+    qibo.set_backend(backend=config.qibo.backend, platform=config.qibo.platform)
+    qibo_time, (qibo_circ, result_sv) = time(
+        lambda: qibo_qft(nqubits, init_state, swaps=True)
+    )
 
     # Convert to qasm for other backends
     qasm_circ = qibo_circ.to_qasm()
 
     # Test quimb
-    start_time = timer()
-    result_tn = qasm_quimb.eval_QI_qft(nqubits=nqubits, qasm_circ=qasm_circ,
-                                       init_state=init_state_for_tn,
-                                       backend=config.quimb['backend'],
-                                       swaps=config.quimb['swaps'])
-    end_time = timer()
-    quimb_time = end_time - start_time
-
-    assert np.allclose(result_sv, result_tn), \
-        "Resulting dense vectors do not match"
+    quimb_time, result_tn = time(
+        lambda: qibotn.quimb.eval(
+            qasm_circ, init_state_tn, backend=config.quimb.backend
+        )
+    )
+
+    assert 1e-2 * qibo_time < quimb_time < 1e2 * qibo_time
+    assert np.allclose(result_sv, result_tn), "Resulting dense vectors do not match"