Add Sycamore23 device (#2547)

* Add Sycamore23 device

- 23 qubit subset of the Sycamore 54 qubit layout
- Update cirq/google/devices/known_devices.py

Co-Authored-By: Casey Duckering <cduck@users.noreply.github.com>

cirq/google/__init__.py

@@ -35,6 +35,7 @@
     Foxtail,
     SerializableDevice,
     Sycamore,
+    Sycamore23,
     XmonDevice,
 )
 

cirq/google/devices/__init__.py

@@ -16,6 +16,7 @@
     Bristlecone,
     Foxtail,
     Sycamore,
+    Sycamore23,
 )
 
 from cirq.google.devices.serializable_device import (

cirq/google/devices/known_devices.py

@@ -280,3 +280,28 @@ def _json_dict_(self):
 Sycamore = SerializableDevice.from_proto(
     proto=SYCAMORE_PROTO,
     gate_sets=[gate_sets.SQRT_ISWAP_GATESET, gate_sets.SYC_GATESET])
+
+
+# Subset of the Sycamore grid with a reduced layout.
+_SYCAMORE23_GRID = """
+----------
+----------
+----------
+--A-------
+-ABC------
+ABCDE-----
+-CDEFG----
+--EFGHI---
+---GHI----
+----I-----
+"""
+
+SYCAMORE23_PROTO = create_device_proto_from_diagram(
+    _SYCAMORE23_GRID,
+    [gate_sets.SQRT_ISWAP_GATESET, gate_sets.SYC_GATESET],
+    _SYCAMORE_DURATIONS_PICOS,
+)
+
+Sycamore23 = SerializableDevice.from_proto(
+    proto=SYCAMORE23_PROTO,
+    gate_sets=[gate_sets.SQRT_ISWAP_GATESET, gate_sets.SYC_GATESET])

cirq/google/devices/known_devices_test.py

@@ -17,6 +17,7 @@
 import cirq
 import cirq.google as cg
 import cirq.google.common_serializers as cgc
+import cirq.google.devices.known_devices as known_devices
 
 
 def test_foxtail_qubits():
@@ -28,7 +29,7 @@ def test_foxtail_qubits():
 
 
 def test_foxtail_device_proto():
-    assert str(cirq.google.devices.known_devices.FOXTAIL_PROTO) == """\
+    assert str(known_devices.FOXTAIL_PROTO) == """\
 valid_gate_sets {
   name: "xmon"
   valid_gates {
@@ -255,7 +256,7 @@ def test_multiple_gate_sets():
         'cz': 11_000,
         'meas': 14_141
     }
-    test_proto = cg.devices.known_devices.create_device_proto_from_diagram(
+    test_proto = known_devices.create_device_proto_from_diagram(
         "aa\naa", [cg.gate_sets.XMON, halfPiGateSet], durations_dict)
     assert str(test_proto) == """\
 valid_gate_sets {
@@ -385,20 +386,36 @@ def test_json_dict():
         'constant': 'cirq.google.Bristlecone',
     }
 
-    from cirq.google.devices.known_devices import _NamedConstantXmonDevice
     with pytest.raises(ValueError, match='xmon device name'):
-        _NamedConstantXmonDevice._from_json_dict_('the_unknown_fiddler')
+        known_devices._NamedConstantXmonDevice._from_json_dict_(
+            'the_unknown_fiddler')
 
 
-def test_sycamore_device():
-    q0 = cirq.GridQubit(5, 4)
-    q1 = cirq.GridQubit(5, 5)
+@pytest.mark.parametrize('device', [cg.Sycamore, cg.Sycamore23])
+def test_sycamore_devices(device):
+    q0 = cirq.GridQubit(5, 3)
+    q1 = cirq.GridQubit(5, 4)
+    syc = cirq.FSimGate(theta=np.pi / 2, phi=np.pi / 6)(q0, q1)
+    sqrt_iswap = cirq.FSimGate(theta=np.pi / 4, phi=0)(q0, q1)
+    device.validate_operation(syc)
+    device.validate_operation(sqrt_iswap)
+    assert device.duration_of(syc) == cirq.Duration(nanos=12)
+    assert device.duration_of(sqrt_iswap) == cirq.Duration(nanos=32)
+
+
+def test_sycamore_grid_layout():
+    # Qubits on Sycamore but not on Sycamore23
+    q0 = cirq.GridQubit(5, 5)
+    q1 = cirq.GridQubit(5, 6)
     syc = cirq.FSimGate(theta=np.pi / 2, phi=np.pi / 6)(q0, q1)
     sqrt_iswap = cirq.FSimGate(theta=np.pi / 4, phi=0)(q0, q1)
     cg.Sycamore.validate_operation(syc)
     cg.Sycamore.validate_operation(sqrt_iswap)
-    assert cg.Sycamore.duration_of(syc) == cirq.Duration(nanos=12)
-    assert cg.Sycamore.duration_of(sqrt_iswap) == cirq.Duration(nanos=32)
+
+    with pytest.raises(ValueError):
+        cg.Sycamore23.validate_operation(syc)
+    with pytest.raises(ValueError):
+        cg.Sycamore23.validate_operation(sqrt_iswap)
 
 
 def test_proto_with_waitgate():

cirq/protocols/json_test.py

@@ -326,6 +326,7 @@ def test_mutually_exclusive_blacklist():
     'StateVectorMixin',
     'SYC_GATESET',
     'Sycamore',
+    'Sycamore23',
     'TextDiagramDrawer',
     'ThreeQubitDiagonalGate',
     'Timestamp',

docs/api.rst

@@ -502,6 +502,7 @@ Functionality specific to quantum hardware and services from Google.
     cirq.google.SerializableGateSet
     cirq.google.SerializingArg
     cirq.google.Sycamore
+    cirq.google.Sycamore23
     cirq.google.SycamoreGate
     cirq.google.XmonDevice