Fix bugs in the analytical pulse shapes (#169)

* Fix bugs in the analytical pulse shapes

- Fix bugs in the analytical pulse shapes
- Compress the test. The test no longer depends on the processor class. Test both the maximum and the total area.

src/qutip_qip/compiler/gatecompiler.py

@@ -437,8 +437,8 @@ def generate_pulse_shape(cls, shape, num_samples, maximum=1.0, area=1.0):
 # subjects more to the finite sampling error under interpolation.
 # More analytical shape can be added here.
 _analytical_window = {
-    "hann": lambda t: 1 / 2 - 1 / 2 * np.cos(2 * np.pi * t),
-    "hamming": lambda t: 0.54 - 0.46 * np.cos(2 * np.pi * t),
+    "hann": lambda t: 1 / 2 - 1 / 2 * np.cos(np.pi * t),
+    "hamming": lambda t: 0.54 - 0.46 * np.cos(np.pi * t * 2 * 0.54),
 }
 
 
@@ -455,7 +455,7 @@ def _normalized_window(shape, num_samples):
         raise ValueError(f"Window function {shape} is not supported.")
     tlist = np.linspace(0, t_max, num_samples)
     if shape in _analytical_window:
-        coeff = _analytical_window["hann"](tlist)
+        coeff = _analytical_window[shape](tlist)
     else:
         coeff = signal.windows.get_window(shape, num_samples)
     return coeff, tlist

tests/test_compiler.py

@@ -1,6 +1,7 @@
 import pytest
 import numpy as np
 from numpy.testing import assert_array_equal
+from scipy import integrate
 from qutip_qip.compiler.gatecompiler import _default_window_t_max
 
 from qutip_qip.device import (
@@ -201,22 +202,11 @@ def test_compiler_result_format():
 
 
 @pytest.mark.parametrize(
-    "shape", list(_default_window_t_max.keys()) + ["rectangular"])
-def test_pulse_shape_scipy(shape):
-    """Test different pulse shape functions imported from scipy"""
-    num_qubits = 1
-    circuit = QubitCircuit(num_qubits)
-    circuit.add_gate("X", 0)
-    processor = LinearSpinChain(num_qubits)
-    compiler = SpinChainCompiler(num_qubits, processor.params)
-    compiler.args.update({"shape": shape, "num_samples": 100})
-    processor.load_circuit(circuit, compiler=compiler)
-    if shape == "rectangular":
-        processor.pulse_mode = "discrete"
-    else:
-        processor.pulse_mode = "continuous"
-    init_state = basis(2, 0)
-    num_result = processor.run_state(init_state).states[-1]
-    ideal_result = circuit.run(init_state)
-    ifid = 1 - fidelity(num_result, ideal_result)
-    assert(pytest.approx(ifid, abs=0.01) == 0)
+    "shape", list(_default_window_t_max.keys()))
+def test_pulse_shape(shape):
+    """Test different pulse shape functions"""
+    coeff, tlist = GateCompiler.generate_pulse_shape(
+        shape, 1001, maximum=1.0, area=1.0)
+    assert pytest.approx(coeff[500], 1.e-2) == 1  # max
+    result = integrate.trapz(coeff, tlist)
+    assert pytest.approx(result, rel=1.e-2) == 1  # area