diff --git a/cirq-core/cirq/_compat.py b/cirq-core/cirq/_compat.py
index 3cc1cdb1e5e..ea4030025f9 100644
--- a/cirq-core/cirq/_compat.py
+++ b/cirq-core/cirq/_compat.py
@@ -192,6 +192,9 @@ def _print(self, expr, **kwargs):
     if hasattr(value, "__qualname__"):
         return f"{value.__module__}.{value.__qualname__}"
 
+    if isinstance(value, np.number):
+        return str(value)
+
     return repr(value)
 
 
diff --git a/cirq-core/cirq/contrib/requirements.txt b/cirq-core/cirq/contrib/requirements.txt
index 9bb5ef009e8..89faa2ab4c6 100644
--- a/cirq-core/cirq/contrib/requirements.txt
+++ b/cirq-core/cirq/contrib/requirements.txt
@@ -4,5 +4,5 @@ ply>=3.6
 pylatex~=1.4
 
 # quimb
-quimb~=1.7
+quimb>=1.8
 opt_einsum
diff --git a/cirq-core/cirq/protocols/circuit_diagram_info_protocol.py b/cirq-core/cirq/protocols/circuit_diagram_info_protocol.py
index 3b6b3445912..03ccf171ac0 100644
--- a/cirq-core/cirq/protocols/circuit_diagram_info_protocol.py
+++ b/cirq-core/cirq/protocols/circuit_diagram_info_protocol.py
@@ -277,6 +277,8 @@ def format_radians(self, radians: Union[sympy.Basic, int, float]) -> str:
         if self.precision is not None and not isinstance(radians, sympy.Basic):
             quantity = self.format_real(radians / np.pi)
             return quantity + unit
+        if isinstance(radians, np.number):
+            return str(radians)
         return repr(radians)
 
     def copy(self):
diff --git a/cirq-core/cirq/protocols/circuit_diagram_info_protocol_test.py b/cirq-core/cirq/protocols/circuit_diagram_info_protocol_test.py
index a1a5baca530..23198efea01 100644
--- a/cirq-core/cirq/protocols/circuit_diagram_info_protocol_test.py
+++ b/cirq-core/cirq/protocols/circuit_diagram_info_protocol_test.py
@@ -208,6 +208,9 @@ def test_format_real():
     assert args.format_real(sympy.Symbol('t')) == 't'
     assert args.format_real(sympy.Symbol('t') * 2 + 1) == '2*t + 1'
 
+    assert args.format_real(np.float64(1.1)) == '1.1'
+    assert args.format_real(np.int32(1)) == '1'
+
     args.precision = None
     assert args.format_real(1) == '1'
     assert args.format_real(1.1) == '1.1'
@@ -252,6 +255,7 @@ def test_format_radians_without_precision():
     assert args.format_radians(-np.pi) == '-pi'
     assert args.format_radians(1.1) == '1.1'
     assert args.format_radians(1.234567) == '1.234567'
+    assert args.format_radians(np.float32(1.234567)) == '1.234567'
     assert args.format_radians(1 / 7) == repr(1 / 7)
     assert args.format_radians(sympy.Symbol('t')) == 't'
     assert args.format_radians(sympy.Symbol('t') * 2 + 1) == '2*t + 1'
@@ -261,6 +265,7 @@ def test_format_radians_without_precision():
     assert args.format_radians(-np.pi) == '-π'
     assert args.format_radians(1.1) == '1.1'
     assert args.format_radians(1.234567) == '1.234567'
+    assert args.format_radians(np.float32(1.234567)) == '1.234567'
     assert args.format_radians(1 / 7) == repr(1 / 7)
     assert args.format_radians(sympy.Symbol('t')) == 't'
     assert args.format_radians(sympy.Symbol('t') * 2 + 1) == '2*t + 1'
diff --git a/cirq-core/cirq/protocols/json_serialization_test.py b/cirq-core/cirq/protocols/json_serialization_test.py
index 82ac67b6278..15334d31f5c 100644
--- a/cirq-core/cirq/protocols/json_serialization_test.py
+++ b/cirq-core/cirq/protocols/json_serialization_test.py
@@ -55,6 +55,13 @@ class _ModuleDeprecation:
     'non_existent_should_be_fine': None,
 }
 
+# TODO(#6706) remove after cirq_rigetti supports NumPy 2.0
+if np.__version__.startswith("2."):  # pragma: no cover
+    warnings.warn(
+        "json_serialization_test - ignoring cirq_rigetti due to incompatibility with NumPy 2.0"
+    )
+    del TESTED_MODULES["cirq_rigetti"]
+
 
 def _get_testspecs_for_modules() -> List[ModuleJsonTestSpec]:
     modules = []
diff --git a/cirq-core/cirq/qis/states.py b/cirq-core/cirq/qis/states.py
index f38ec81d010..5d3803fe8f7 100644
--- a/cirq-core/cirq/qis/states.py
+++ b/cirq-core/cirq/qis/states.py
@@ -264,7 +264,7 @@ def quantum_state(
             dtype = DEFAULT_COMPLEX_DTYPE
         data = one_hot(index=state, shape=(dim,), dtype=dtype)
     else:
-        data = np.array(state, copy=False)
+        data = np.asarray(state)
         if qid_shape is None:
             qid_shape = infer_qid_shape(state)
         if data.ndim == 1 and data.dtype.kind != 'c':
diff --git a/cirq-core/cirq/sim/simulator.py b/cirq-core/cirq/sim/simulator.py
index 2608482b6a0..66104a43f5e 100644
--- a/cirq-core/cirq/sim/simulator.py
+++ b/cirq-core/cirq/sim/simulator.py
@@ -912,7 +912,7 @@ def __repr__(self) -> str:
     def __str__(self) -> str:
         def bitstring(vals):
             separator = ' ' if np.max(vals) >= 10 else ''
-            return separator.join(str(int(v)) for v in vals)
+            return separator.join(str(v.item()) for v in vals)
 
         results = sorted([(key, bitstring(val)) for key, val in self.measurements.items()])
         if not results:
diff --git a/cirq-core/cirq/sim/sparse_simulator_test.py b/cirq-core/cirq/sim/sparse_simulator_test.py
index d07e95ecd86..b4445026e6d 100644
--- a/cirq-core/cirq/sim/sparse_simulator_test.py
+++ b/cirq-core/cirq/sim/sparse_simulator_test.py
@@ -115,7 +115,7 @@ def test_run_repetitions_terminal_measurement_stochastic():
     q = cirq.LineQubit(0)
     c = cirq.Circuit(cirq.H(q), cirq.measure(q, key='q'))
     results = cirq.Simulator().run(c, repetitions=10000)
-    assert 1000 <= sum(v[0] for v in results.measurements['q']) < 9000
+    assert 1000 <= np.count_nonzero(results.measurements['q']) < 9000
 
 
 @pytest.mark.parametrize('dtype', [np.complex64, np.complex128])
@@ -255,7 +255,7 @@ def test_run_mixture(dtype: Type[np.complexfloating], split: bool):
     simulator = cirq.Simulator(dtype=dtype, split_untangled_states=split)
     circuit = cirq.Circuit(cirq.bit_flip(0.5)(q0), cirq.measure(q0))
     result = simulator.run(circuit, repetitions=100)
-    assert 20 < sum(result.measurements['q(0)'])[0] < 80
+    assert 20 < np.count_nonzero(result.measurements['q(0)']) < 80
 
 
 @pytest.mark.parametrize('dtype', [np.complex64, np.complex128])
@@ -265,8 +265,8 @@ def test_run_mixture_with_gates(dtype: Type[np.complexfloating], split: bool):
     simulator = cirq.Simulator(dtype=dtype, split_untangled_states=split, seed=23)
     circuit = cirq.Circuit(cirq.H(q0), cirq.phase_flip(0.5)(q0), cirq.H(q0), cirq.measure(q0))
     result = simulator.run(circuit, repetitions=100)
-    assert sum(result.measurements['q(0)'])[0] < 80
-    assert sum(result.measurements['q(0)'])[0] > 20
+    assert np.count_nonzero(result.measurements['q(0)']) < 80
+    assert np.count_nonzero(result.measurements['q(0)']) > 20
 
 
 @pytest.mark.parametrize('dtype', [np.complex64, np.complex128])
diff --git a/cirq-core/requirements.txt b/cirq-core/requirements.txt
index b526c835455..fc39ec8c005 100644
--- a/cirq-core/requirements.txt
+++ b/cirq-core/requirements.txt
@@ -4,10 +4,10 @@ attrs>=21.3.0
 duet>=0.2.8
 matplotlib~=3.0
 networkx>=2.4
-numpy~=1.22
+numpy>=1.24
 pandas
 sortedcontainers~=2.0
-scipy~=1.0
+scipy~=1.8
 sympy
 typing_extensions>=4.2
 tqdm
diff --git a/cirq-google/cirq_google/serialization/arg_func_langs.py b/cirq-google/cirq_google/serialization/arg_func_langs.py
index b725f0b84e3..82104ad5a19 100644
--- a/cirq-google/cirq_google/serialization/arg_func_langs.py
+++ b/cirq-google/cirq_google/serialization/arg_func_langs.py
@@ -474,9 +474,9 @@ def clifford_tableau_arg_to_proto(
     msg = v2.program_pb2.CliffordTableau() if out is None else out
     msg.num_qubits = value.n
     msg.initial_state = value.initial_state
-    msg.xs.extend(value.xs.flatten())
-    msg.rs.extend(value.rs.flatten())
-    msg.zs.extend(value.zs.flatten())
+    msg.xs.extend(map(bool, value.xs.flatten()))
+    msg.rs.extend(map(bool, value.rs.flatten()))
+    msg.zs.extend(map(bool, value.zs.flatten()))
     return msg
 
 
diff --git a/conftest.py b/conftest.py
index d61f5277b2b..668abd5efea 100644
--- a/conftest.py
+++ b/conftest.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import pytest
+import numpy as np
 
 
 def pytest_addoption(parser):
@@ -25,6 +26,19 @@ def pytest_addoption(parser):
     parser.addoption(
         "--enable-slow-tests", action="store_true", default=False, help="run slow tests"
     )
+    parser.addoption(
+        "--warn-numpy-data-promotion",
+        action="store_true",
+        default=False,
+        help="enable NumPy 2 data type promotion warnings",
+    )
+
+
+def pytest_configure(config):
+    # If requested, globally enable verbose NumPy 2 warnings about data type
+    # promotion. See https://numpy.org/doc/2.0/numpy_2_0_migration_guide.html.
+    if config.option.warn_numpy_data_promotion:
+        np._set_promotion_state("weak_and_warn")
 
 
 def pytest_collection_modifyitems(config, items):
diff --git a/dev_tools/requirements/dev-np2.env.txt b/dev_tools/requirements/dev-np2.env.txt
new file mode 100644
index 00000000000..6c86721cebe
--- /dev/null
+++ b/dev_tools/requirements/dev-np2.env.txt
@@ -0,0 +1,17 @@
+# This file describes a development environment for cirq with NumPy-2
+# It skips cirq_rigetti which has dependencies incompatible with NumPy-2.
+#
+# TODO(#6706) remove this file after cirq_rigetti supports NumPy 2.0
+
+# dev.env.txt expanded without cirq-rigetti ----------------------------------
+
+-r ../../cirq-aqt/requirements.txt
+-r ../../cirq-core/requirements.txt
+-r ../../cirq-google/requirements.txt
+-r ../../cirq-core/cirq/contrib/requirements.txt
+
+-r deps/dev-tools.txt
+
+# own rules ------------------------------------------------------------------
+
+numpy>=2
diff --git a/examples/bb84.py b/examples/bb84.py
index ffe5adcb584..dcaf1c82b58 100644
--- a/examples/bb84.py
+++ b/examples/bb84.py
@@ -128,7 +128,7 @@ def main(num_qubits=8):
     repetitions = 1
 
     result = cirq.Simulator().run(program=circuit, repetitions=repetitions)
-    result_bitstring = bitstring([int(result.measurements[str(q)]) for q in qubits])
+    result_bitstring = bitstring([result.measurements[str(q)].item() for q in qubits])
 
     # Take only qubits where bases match
     obtained_key = ''.join(
@@ -158,14 +158,14 @@ def main(num_qubits=8):
     # Run simulations.
     repetitions = 1
     result = cirq.Simulator().run(program=alice_eve_circuit, repetitions=repetitions)
-    eve_state = [int(result.measurements[str(q)]) for q in qubits]
+    eve_state = [result.measurements[str(q)].item() for q in qubits]
 
     eve_bob_circuit = make_bb84_circ(num_qubits, eve_basis, bob_basis, eve_state)
 
     # Run simulations.
     repetitions = 1
     result = cirq.Simulator().run(program=eve_bob_circuit, repetitions=repetitions)
-    result_bitstring = bitstring([int(result.measurements[str(q)]) for q in qubits])
+    result_bitstring = bitstring([result.measurements[str(q)].item() for q in qubits])
 
     # Take only qubits where bases match
     obtained_key = ''.join(