one hot encoding

qualtran/bloqs/data_loading/one_hot_encoding.py

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+#  Copyright 2023 Google LLC
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  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 attrs
+import cirq
+from attr import field
+from numpy._typing import NDArray
+
+from qualtran import GateWithRegisters, QAny, QUInt, Signature
+from qualtran.bloqs.basic_gates import TwoBitCSwap
+
+
+@attrs.frozen
+class OneHotEncoding(GateWithRegisters):
+    """
+    One-hot encode a binary integer into a target register.
+
+    Registers:
+        a: an unsigned integer
+        b: the target to one-hot encode.
+
+    References:
+        [Windowed quantum arithmetic](https://arxiv.org/pdf/1905.07682.pdf)
+        Figure 4]
+    """
+
+    binary_reg_size: int = field()
+
+    @property
+    def signature(self) -> 'Signature':
+        return Signature.build_from_dtypes(
+            a=QUInt(self.binary_reg_size), b=QAny(2**self.binary_reg_size)
+        )
+
+    def decompose_from_registers(
+        self, *, context: cirq.DecompositionContext, **quregs: NDArray[cirq.Qid]
+    ) -> cirq.OP_TREE:
+        a = quregs['a']
+        b = quregs['b']
+
+        yield cirq.X(b[0])
+        for i in range(len(a)):
+            for j in range(2**i):
+                yield TwoBitCSwap().on_registers(ctrl=a[i], x=b[j], y=b[2**i + j])

qualtran/bloqs/data_loading/one_hot_encoding_test.py

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+#  Copyright 2023 Google LLC
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  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 attrs
+import cirq
+import pytest
+from attr import field
+from numpy._typing import NDArray
+
+from qualtran import GateWithRegisters, QUInt, Signature
+from qualtran.bloqs.data_loading.one_hot_encoding import OneHotEncoding
+from qualtran.cirq_interop.bit_tools import iter_bits
+from qualtran.cirq_interop.testing import assert_circuit_inp_out_cirqsim
+
+
+@attrs.frozen
+class OneHotEncodingTest(GateWithRegisters):
+    integer: int = field()
+    size: int = field()
+
+    @property
+    def signature(self) -> 'Signature':
+        return Signature.build_from_dtypes(a=QUInt(self.size), b=QUInt(2**self.size))
+
+    def decompose_from_registers(
+        self, *, context: cirq.DecompositionContext, **quregs: NDArray[cirq.Qid]
+    ) -> cirq.OP_TREE:
+        a = quregs['a']
+        b = quregs['b']
+        binary_repr = list(iter_bits(self.integer, self.size))[::-1]
+        for i in range(self.size):
+            if binary_repr[i] == 1:
+                yield cirq.X(a[i])
+        yield OneHotEncoding(binary_reg_size=self.size).on_registers(a=a, b=b)
+
+
+@pytest.mark.parametrize('integer', list(range(8)))
+def test_one_hot_encoding(integer):
+    gate = OneHotEncodingTest(integer, 3)
+    qubits = cirq.LineQubit.range(3 + 2**3)
+    op = gate.on_registers(a=qubits[:3], b=qubits[3:])
+    circuit0 = cirq.Circuit(op)
+    initial_state = [0] * (3 + 2**3)
+    final_state = [0] * (3 + 2**3)
+    final_state[:3] = list(iter_bits(integer, 3))[::-1]
+    final_state[3 + integer] = 1
+    assert_circuit_inp_out_cirqsim(circuit0, qubits, initial_state, final_state)