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Merged
merged 4 commits into from
Oct 16, 2021
Merged

Bring canonicalization of FSimGate and PhasedFSimGate angles b/w [-pi, pi) #4576

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8d438b3
Bring canonicalization of fsim/phasedfsim angles b/w (-pi, pi]
tanujkhattar Oct 14, 2021
cb9328b
Merge branch 'master' of https://github.com/quantumlib/cirq into fsim…
tanujkhattar Oct 16, 2021
6d9e13e
Get rid of numerical error in fsim angles canonicalization
tanujkhattar Oct 16, 2021
81a5216
Fix common serializer tests
tanujkhattar Oct 16, 2021
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10 changes: 5 additions & 5 deletions cirq-core/cirq/ops/fsim_gate.py
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Original file line number Diff line number Diff line change
Expand Up @@ -35,20 +35,20 @@


def _canonicalize(value: Union[float, sympy.Basic]) -> Union[float, sympy.Basic]:
"""Assumes value is 2π-periodic and shifts it into [-π, π]."""
"""Assumes value is 2π-periodic and shifts it into [-π, π)."""
if protocols.is_parameterized(value):
return value
period = 2 * np.pi
return value - period * np.round(value / period)
return value - period * np.floor((value + np.pi) / period)


def _zero_mod_pi(param: Union[float, sympy.Basic]) -> bool:
"""Returns True iff param, assumed to be in [-pi, pi], is 0 (mod pi)."""
return param in (-np.pi, 0.0, np.pi, -sympy.pi, sympy.pi)
"""Returns True iff param, assumed to be in [-pi, pi), is 0 (mod pi)."""
return param in (0.0, -np.pi, -sympy.pi)
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Optional: We could add an assert to verify that param is in [-pi, pi). Now that the result of these calculations will be used for equality checks, it's probably better to have the code crash and signal a bug than silently pretend equal things are different.

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The equality checks are done by directly comparing the self.theta etc. angles, and these functions are also called only with the class angles, which are always canonicalized. I could add an assert to the _canonicalize method which ensures that the return value is between [-pi, pi), but the tests already ensure that the method works as expected so I don't think the assert is needed.



def _half_pi_mod_pi(param: Union[float, sympy.Basic]) -> bool:
"""Returns True iff param, assumed to be in [-pi, pi], is pi/2 (mod pi)."""
"""Returns True iff param, assumed to be in [-pi, pi), is pi/2 (mod pi)."""
return param in (-np.pi / 2, np.pi / 2, -sympy.pi / 2, sympy.pi / 2)


Expand Down
47 changes: 26 additions & 21 deletions cirq-core/cirq/ops/fsim_gate_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ def test_fsim_eq():
eq.add_equality_group(cirq.FSimGate(0, 0))
eq.add_equality_group(cirq.FSimGate(1, 1))
eq.add_equality_group(cirq.FSimGate(1, 2).on(a, b), cirq.FSimGate(1, 2).on(b, a))
eq.add_equality_group(cirq.FSimGate(np.pi, np.pi), cirq.FSimGate(-np.pi, -np.pi))


def test_fsim_approx_eq():
Expand Down Expand Up @@ -73,26 +74,26 @@ def test_fsim_circuit():
cirq.testing.assert_has_diagram(
c,
"""
0: ───FSim(0.5π, π)───FSim(-π, 0.5π)───
│ │
1: ───FSim(0.5π, π)───FSim(-π, 0.5π)───
0: ───FSim(0.5π, -π)───FSim(-π, 0.5π)───
│ │
1: ───FSim(0.5π, -π)───FSim(-π, 0.5π)───
""",
)
cirq.testing.assert_has_diagram(
c,
"""
0: ---FSim(0.5pi, pi)---FSim(-pi, 0.5pi)---
| |
1: ---FSim(0.5pi, pi)---FSim(-pi, 0.5pi)---
0: ---FSim(0.5pi, -pi)---FSim(-pi, 0.5pi)---
| |
1: ---FSim(0.5pi, -pi)---FSim(-pi, 0.5pi)---
""",
use_unicode_characters=False,
)
cirq.testing.assert_has_diagram(
c,
"""
0: ---FSim(1.5707963267948966, pi)---FSim(-pi, 1.5707963267948966)---
| |
1: ---FSim(1.5707963267948966, pi)---FSim(-pi, 1.5707963267948966)---
0: ---FSim(1.5707963267948966, -pi)---FSim(-pi, 1.5707963267948966)---
| |
1: ---FSim(1.5707963267948966, -pi)---FSim(-pi, 1.5707963267948966)---
""",
use_unicode_characters=False,
precision=None,
Expand Down Expand Up @@ -379,6 +380,10 @@ def test_phased_fsim_eq():
eq.add_equality_group(cirq.PhasedFSimGate(1, s, 0, 0, 0))
eq.add_equality_group(cirq.PhasedFSimGate(r, 1, 0, 0, 0))
eq.add_equality_group(cirq.PhasedFSimGate(s, 1, 0, 0, 0))
eq.add_equality_group(
cirq.PhasedFSimGate(np.pi, np.pi, np.pi, np.pi, np.pi),
cirq.PhasedFSimGate(-np.pi, -np.pi, -np.pi, -np.pi, -np.pi),
)

# Regions of insensitivity to zeta and chi
eq.add_equality_group(
Expand All @@ -392,7 +397,7 @@ def test_phased_fsim_eq():
cirq.PhasedFSimGate(sympy.pi / 2, 0, 0, 4, 5), cirq.PhasedFSimGate(sympy.pi / 2, 2, 0, 4, 5)
)
eq.add_equality_group(
cirq.PhasedFSimGate(sympy.pi, 0, 0, 4, 5), cirq.PhasedFSimGate(sympy.pi, 0, 3, 4, 5)
cirq.PhasedFSimGate(-sympy.pi, 0, 0, 4, 5), cirq.PhasedFSimGate(-sympy.pi, 0, 3, 4, 5)
)

# Symmetries under qubit exchange
Expand All @@ -410,8 +415,8 @@ def test_phased_fsim_eq():
cirq.PhasedFSimGate(1, -np.pi, np.pi, 4, 5).on(b, a),
)
eq.add_equality_group(
cirq.PhasedFSimGate(1, sympy.pi, -sympy.pi, r, 5).on(a, b),
cirq.PhasedFSimGate(1, sympy.pi, -sympy.pi, r, 5).on(b, a),
cirq.PhasedFSimGate(1, -sympy.pi, -sympy.pi, r, 5).on(a, b),
cirq.PhasedFSimGate(1, -sympy.pi, -sympy.pi, r, 5).on(b, a),
)
eq.add_equality_group(cirq.PhasedFSimGate(sympy.pi / 3, 2, 0, 4, 5).on(a, b))
eq.add_equality_group(cirq.PhasedFSimGate(sympy.pi / 3, 2, 0, 4, 5).on(b, a))
Expand Down Expand Up @@ -479,27 +484,27 @@ def test_phased_fsim_circuit():
cirq.testing.assert_has_diagram(
c,
"""
0: ───PhFSim(0.5π, π, 0.5π, 0, -0.25π)───PhFSim(-π, 0.5π, 0.1π, 0.2π, 0.3π)───
│ │
1: ───PhFSim(0.5π, π, 0.5π, 0, -0.25π)───PhFSim(-π, 0.5π, 0.1π, 0.2π, 0.3π)───
0: ───PhFSim(0.5π, -π, 0.5π, 0, -0.25π)───PhFSim(-π, 0.5π, 0.1π, 0.2π, 0.3π)───
│ │
1: ───PhFSim(0.5π, -π, 0.5π, 0, -0.25π)───PhFSim(-π, 0.5π, 0.1π, 0.2π, 0.3π)───
""",
)
# pylint: disable=line-too-long
cirq.testing.assert_has_diagram(
c,
"""
0: ---PhFSim(0.5pi, pi, 0.5pi, 0, -0.25pi)---PhFSim(-pi, 0.5pi, 0.1pi, 0.2pi, 0.3pi)---
| |
1: ---PhFSim(0.5pi, pi, 0.5pi, 0, -0.25pi)---PhFSim(-pi, 0.5pi, 0.1pi, 0.2pi, 0.3pi)---
0: ---PhFSim(0.5pi, -pi, 0.5pi, 0, -0.25pi)---PhFSim(-pi, 0.5pi, 0.1pi, 0.2pi, 0.3pi)---
| |
1: ---PhFSim(0.5pi, -pi, 0.5pi, 0, -0.25pi)---PhFSim(-pi, 0.5pi, 0.1pi, 0.2pi, 0.3pi)---
""",
use_unicode_characters=False,
)
cirq.testing.assert_has_diagram(
c,
"""
0: ---PhFSim(1.5707963267948966, pi, 1.5707963267948966, 0, -0.7853981633974483)---PhFSim(-pi, 1.5707963267948966, 0.3141592653589793, 0.6283185307179586, 0.9424777960769379)---
| |
1: ---PhFSim(1.5707963267948966, pi, 1.5707963267948966, 0, -0.7853981633974483)---PhFSim(-pi, 1.5707963267948966, 0.3141592653589793, 0.6283185307179586, 0.9424777960769379)---
0: ---PhFSim(1.5707963267948966, -pi, 1.5707963267948966, 0, -0.7853981633974483)---PhFSim(-pi, 1.5707963267948966, 0.3141592653589793, 0.6283185307179586, 0.9424777960769379)---
| |
1: ---PhFSim(1.5707963267948966, -pi, 1.5707963267948966, 0, -0.7853981633974483)---PhFSim(-pi, 1.5707963267948966, 0.3141592653589793, 0.6283185307179586, 0.9424777960769379)---
""",
use_unicode_characters=False,
precision=None,
Expand Down
3 changes: 2 additions & 1 deletion cirq-google/cirq_google/serialization/common_serializers_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -556,7 +556,8 @@ def test_wait_gate_multi_qubit():
(cirq.CZ, 0, np.pi),
(cirq.CZ ** -1.0, 0, np.pi),
(cirq.FSimGate(theta=0, phi=0), 0, 0),
(cirq.FSimGate(theta=0, phi=np.pi), 0, np.pi),
(cirq.FSimGate(theta=0, phi=np.pi), 0, -np.pi),
(cirq.FSimGate(theta=0, phi=-np.pi), 0, -np.pi),
(cirq.FSimGate(theta=np.pi / 4, phi=0), np.pi / 4, 0),
(cirq.FSimGate(theta=7 * np.pi / 4, phi=0), -np.pi / 4, 0),
(cirq.FSimGate(theta=-np.pi / 4, phi=0), -np.pi / 4, 0),
Expand Down