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The following commit(s) were added to refs/heads/main by this push:
new 5babd9839 MAHOUT-624: add qubit index validation to prevent
out-of-bounds access (#627)
5babd9839 is described below
commit 5babd983968caeaa180d392cd8e440b95c304c65
Author: Shivam Mittal <[email protected]>
AuthorDate: Fri Nov 14 15:04:09 2025 +0530
MAHOUT-624: add qubit index validation to prevent out-of-bounds access
(#627)
---
qumat/qumat.py | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/qumat/qumat.py b/qumat/qumat.py
index 3bccc8c93..31c5adb49 100644
--- a/qumat/qumat.py
+++ b/qumat/qumat.py
@@ -78,6 +78,28 @@ class QuMat:
"before applying gates or executing operations."
)
+ def _validate_qubit_index(self, qubit_index, param_name="qubit_index"):
+ """validate qubit index is within circuit bounds.
+
+ :param qubit_index: the qubit index to validate.
+ :type qubit_index: int
+ :param param_name: name of the parameter for error messages.
+ :type param_name: str
+ :raises TypeError: if qubit_index is not an integer.
+ :raises ValueError: if qubit_index is negative or out of range.
+ """
+ if not isinstance(qubit_index, int):
+ raise TypeError(
+ f"{param_name} must be an integer, got
{type(qubit_index).__name__}"
+ )
+ if qubit_index < 0:
+ raise ValueError(f"{param_name} cannot be negative, got
{qubit_index}")
+ if self.num_qubits is not None and qubit_index >= self.num_qubits:
+ raise ValueError(
+ f"{param_name} {qubit_index} out of range for circuit with "
+ f"{self.num_qubits} qubits (valid range: 0-{self.num_qubits -
1})"
+ )
+
def apply_not_gate(self, qubit_index):
"""Apply a NOT gate (Pauli-X gate) to the specified qubit.
@@ -89,6 +111,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_not_gate(self.circuit, qubit_index)
def apply_hadamard_gate(self, qubit_index):
@@ -102,6 +125,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_hadamard_gate(self.circuit, qubit_index)
def apply_cnot_gate(self, control_qubit_index, target_qubit_index):
@@ -117,6 +141,8 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(control_qubit_index, "control_qubit_index")
+ self._validate_qubit_index(target_qubit_index, "target_qubit_index")
self.backend_module.apply_cnot_gate(
self.circuit, control_qubit_index, target_qubit_index
)
@@ -138,6 +164,9 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(control_qubit_index1,
"control_qubit_index1")
+ self._validate_qubit_index(control_qubit_index2,
"control_qubit_index2")
+ self._validate_qubit_index(target_qubit_index, "target_qubit_index")
self.backend_module.apply_toffoli_gate(
self.circuit, control_qubit_index1, control_qubit_index2,
target_qubit_index
)
@@ -152,6 +181,8 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index1, "qubit_index1")
+ self._validate_qubit_index(qubit_index2, "qubit_index2")
self.backend_module.apply_swap_gate(self.circuit, qubit_index1,
qubit_index2)
def apply_cswap_gate(
@@ -171,6 +202,9 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(control_qubit_index, "control_qubit_index")
+ self._validate_qubit_index(target_qubit_index1, "target_qubit_index1")
+ self._validate_qubit_index(target_qubit_index2, "target_qubit_index2")
self.backend_module.apply_cswap_gate(
self.circuit, control_qubit_index, target_qubit_index1,
target_qubit_index2
)
@@ -186,6 +220,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_pauli_x_gate(self.circuit, qubit_index)
def apply_pauli_y_gate(self, qubit_index):
@@ -199,6 +234,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_pauli_y_gate(self.circuit, qubit_index)
def apply_pauli_z_gate(self, qubit_index):
@@ -212,6 +248,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_pauli_z_gate(self.circuit, qubit_index)
def execute_circuit(self, parameter_values=None):
@@ -307,6 +344,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self._handle_parameter(angle)
self.backend_module.apply_rx_gate(self.circuit, qubit_index, angle)
@@ -325,6 +363,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self._handle_parameter(angle)
self.backend_module.apply_ry_gate(self.circuit, qubit_index, angle)
@@ -343,6 +382,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self._handle_parameter(angle)
self.backend_module.apply_rz_gate(self.circuit, qubit_index, angle)
@@ -376,6 +416,7 @@ class QuMat:
:raises RuntimeError: If the circuit has not been initialized.
"""
self._ensure_circuit_initialized()
+ self._validate_qubit_index(qubit_index)
self.backend_module.apply_u_gate(self.circuit, qubit_index, theta,
phi, lambd)
def swap_test(self, ancilla_qubit, qubit1, qubit2):
