Remove checks so that hold_time is sweepable (quantumlib#5919)

Allows the hold time in `CouplerPulse` to be swept.
See quantumlib#5918

Author: eliottrosenberg

cirq-google/cirq_google/experimental/ops/coupler_pulse.py

@@ -19,10 +19,6 @@
 import cirq
 
 
-_MIN_DURATION = cirq.Duration(nanos=0)
-_MAX_DURATION = cirq.Duration(nanos=200)
-
-
 @cirq.value_equality(approximate=True)
 class CouplerPulse(cirq.ops.Gate):
     r"""Tunable pulse for entangling adjacent qubits.
@@ -67,28 +63,12 @@ def __init__(
             rise_time: Width of the rising (or falling) action of the trapezoidal pulse.
             padding_time: Symmetric padding around the coupler pulse.
 
-        Raises:
-            ValueError: If any time is negative or if the total pulse is too long.
         """
-        if hold_time < _MIN_DURATION:
-            raise ValueError(f'hold_time must be greater than {_MIN_DURATION}')
-        if padding_time < _MIN_DURATION:
-            raise ValueError(f'padding_time must be greater than {_MIN_DURATION}')
-        if rise_time < _MIN_DURATION:
-            raise ValueError(f'rise_time must be greater than {_MIN_DURATION}')
-
         self.hold_time = hold_time
         self.coupling_mhz = coupling_mhz
         self.rise_time = rise_time or cirq.Duration(nanos=8)
         self.padding_time = padding_time or cirq.Duration(nanos=2.5)
 
-        total_time = hold_time + 2 * self.rise_time + 2 * self.padding_time
-        if total_time > _MAX_DURATION:
-            raise ValueError(
-                f'Total time of coupler pulse ({total_time}) '
-                f'cannot be greater than {_MAX_DURATION}'
-            )
-
     def num_qubits(self) -> int:
         return 2
 

cirq-google/cirq_google/experimental/ops/coupler_pulse_test.py

@@ -11,7 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import pytest
 
 import cirq
 import cirq_google.experimental.ops.coupler_pulse as coupler_pulse
@@ -80,39 +79,6 @@ def test_equality():
     )
 
 
-def test_coupler_pulse_validation():
-    with pytest.raises(ValueError, match='Total time of coupler pulse'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=210), coupling_mhz=25.0, rise_time=cirq.Duration(nanos=10)
-        )
-    with pytest.raises(ValueError, match='hold_time must be greater'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=-10), coupling_mhz=25.0, rise_time=cirq.Duration(nanos=20)
-        )
-    with pytest.raises(ValueError, match='Total time of coupler pulse'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=10),
-            coupling_mhz=25.0,
-            rise_time=cirq.Duration(nanos=20),
-            padding_time=cirq.Duration(nanos=200),
-        )
-    with pytest.raises(ValueError, match='padding_time must be greater'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=10),
-            coupling_mhz=25.0,
-            rise_time=cirq.Duration(nanos=20),
-            padding_time=cirq.Duration(nanos=-20),
-        )
-    with pytest.raises(ValueError, match='rise_time must be greater'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=10), coupling_mhz=25.0, rise_time=cirq.Duration(nanos=-1)
-        )
-    with pytest.raises(ValueError, match='Total time of coupler pulse'):
-        _ = coupler_pulse.CouplerPulse(
-            hold_time=cirq.Duration(nanos=10), coupling_mhz=25.0, rise_time=cirq.Duration(nanos=302)
-        )
-
-
 def test_coupler_pulse_str_repr():
     gate = coupler_pulse.CouplerPulse(
         hold_time=cirq.Duration(nanos=10), coupling_mhz=25.0, rise_time=cirq.Duration(nanos=18)