QuMat Class Methods

__init__(self, backend_config)

• Purpose: Initializes the QuMat instance with a specific backend.
• Parameters:
  • backend_config (dict): Configuration for the backend including its name and options.
• Usage: Used to set up the quantum computing backend based on user configuration.

create_empty_circuit(self, num_qubits)

• Purpose: Creates an empty quantum circuit with a specified number of qubits.
• Parameters:
  • num_qubits (int): Number of qubits in the quantum circuit.
• Usage: Used at the start of quantum computations to prepare a new quantum circuit.

apply_not_gate(self, qubit_index)

• Purpose: Applies a NOT gate (quantum equivalent of a classical NOT) to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit to which the gate is applied.
• Usage: Used to flip the state of a qubit from 0 to 1 or from 1 to 0.

apply_hadamard_gate(self, qubit_index)

• Purpose: Applies a Hadamard gate to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit.
• Usage: Used to create a superposition state, allowing the qubit to be both 0 and 1 simultaneously.

apply_cnot_gate(self, control_qubit_index, target_qubit_index)

• Purpose: Applies a Controlled-NOT (CNOT) gate between two qubits.
• Parameters:
  • control_qubit_index (int): Index of the control qubit.
  • target_qubit_index (int): Index of the target qubit.
• Usage: Fundamental for entangling qubits, which is essential for quantum algorithms.

apply_toffoli_gate(self, control_qubit_index1, control_qubit_index2, target_qubit_index)

• Purpose: Applies a Toffoli gate (CCX gate) to three qubits.
• Parameters:
  • control_qubit_index1 (int): Index of the first control qubit.
  • control_qubit_index2 (int): Index of the second control qubit.
  • target_qubit_index (int): Index of the target qubit.
• Usage: Acts as a quantum AND gate, used in algorithms requiring conditional logic.

apply_swap_gate(self, qubit_index1, qubit_index2)

• Purpose: Swaps the states of two qubits.
• Parameters:
  • qubit_index1 (int): Index of the first qubit.
  • qubit_index2 (int): Index of the second qubit.
• Usage: Useful in quantum algorithms for rearranging qubit states.

apply_cswap_gate(self, control_qubit_index, target_qubit_index1, target_qubit_index2)

• Purpose: Applies a controlled-SWAP (Fredkin) gate that swaps two targets when the control is |1⟩.
• Parameters:
  • control_qubit_index (int): Index of the control qubit.
  • target_qubit_index1 (int): Index of the first target qubit.
  • target_qubit_index2 (int): Index of the second target qubit.
• Usage: Used in overlap estimation routines such as the swap test.

apply_pauli_x_gate(self, qubit_index)

• Purpose: Applies a Pauli-X gate to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit.
• Usage: Equivalent to a NOT gate, flips the qubit state.

apply_pauli_y_gate(self, qubit_index)

• Purpose: Applies a Pauli-Y gate to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit.
• Usage: Impacts the phase and amplitude of a qubit's state.

apply_pauli_z_gate(self, qubit_index)

• Purpose: Applies a Pauli-Z gate to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit.
• Usage: Alters the phase of a qubit without changing its amplitude.

apply_t_gate(self, qubit_index)

• Purpose: Applies the T (π/8) phase gate to a specified qubit.
• Parameters:
  • qubit_index (int): Index of the qubit.
• Usage: Adds a π/4 phase to |1⟩. Together with the Hadamard (H) and CNOT gates, it enables universal single-qubit control.

execute_circuit(self)

• Purpose: Executes the quantum circuit and retrieves the results.
• Usage: Used to run the entire set of quantum operations and measure the outcomes.

get_final_state_vector(self)

• Purpose: Returns the final state vector of the circuit from the configured backend.
• Usage: Retrieves the full quantum state for simulation and analysis workflows.

draw_circuit(self)

• Purpose: Visualizes the quantum circuit.
• Returns: A string representation of the circuit visualization (format depends on backend).
• Usage: Returns a visualization string that can be printed or used programmatically. Example: print(qc.draw_circuit()) or viz = qc.draw_circuit().
• Note: Uses underlying libraries' methods for drawing circuits (Qiskit's draw(), Cirq's str(), or Braket's str()).

apply_rx_gate(self, qubit_index, angle)

• Purpose: Applies a rotation around the X-axis to a specified qubit with an optional parameter for optimization.
• Parameters:
  • qubit_index (int): Index of the qubit.
  • angle (str or float): Angle in radians for the rotation. Can be a static value or a parameter name for optimization.
• Usage: Used to rotate a qubit around the X-axis, often in parameterized quantum circuits for variational algorithms.

apply_ry_gate(self, qubit_index, angle)

• Purpose: Applies a rotation around the Y-axis to a specified qubit with an optional parameter for optimization.
• Parameters:
  • qubit_index (int): Index of the qubit.
  • angle (str or float): Angle in radians for the rotation. Can be a static value or a parameter name for optimization.
• Usage: Used to rotate a qubit around the Y-axis in parameterized circuits, aiding in the creation of complex quantum states.

apply_rz_gate(self, qubit_index, angle)

• Purpose: Applies a rotation around the Z-axis to a specified qubit with an optional parameter for optimization.
• Parameters:
  • qubit_index (int): Index of the qubit.
  • angle (str or float): Angle in radians for the rotation. Can be a static value or a parameter name for optimization.
• Usage: Utilized in parameterized quantum circuits to modify the phase of a qubit state during optimization.

apply_u_gate(self, qubit_index, theta, phi, lambd)

• Purpose: Applies the universal single-qubit U(θ, φ, λ) gate.
• Parameters:
  • qubit_index (int): Index of the qubit.
  • theta (float): Rotation angle θ.
  • phi (float): Rotation angle φ.
  • lambd (float): Rotation angle λ.
• Usage: Provides full single-qubit unitary control via Z–Y–Z Euler decomposition.

execute_circuit(self, parameter_values=None)

• Purpose: Executes the quantum circuit with the ability to bind specific parameter values if provided.
• Parameters:
  • parameter_values (dict, optional): A dictionary where keys are parameter names and values are the numerical values to bind.
• Usage: Enables the execution of parameterized circuits by binding parameter values, facilitating optimization processes.

bind_parameters(self, parameter_values)

• Purpose: Binds numerical values to the parameters of the quantum circuit, allowing for dynamic updates during optimization.
• Parameters:
  • parameter_values (dict): A dictionary with parameter names as keys and numerical values to bind.
• Usage: Essential for optimization loops where parameters are adjusted based on cost function evaluations.

_handle_parameter(self, param_name)

• Purpose: Internal function to manage parameter registration.
• Parameters:
  • param_name (str): The name of the parameter to handle.
• Usage: Automatically invoked when applying parameterized gates to keep track of parameters efficiently.

swap_test(self, ancilla_qubit, qubit1, qubit2)

• Purpose: Builds the swap-test subcircuit (H–CSWAP–H) to compare two quantum states.
• Parameters:
  • ancilla_qubit (int): Index of the ancilla control qubit.
  • qubit1 (int): Index of the first state qubit.
  • qubit2 (int): Index of the second state qubit.
• Usage: Used in overlap/fidelity estimation between two states.

measure_overlap(self, qubit1, qubit2, ancilla_qubit=0)

• Purpose: Executes the swap test and returns |⟨ψ|φ⟩|² using backend-specific measurement parsing.
• Parameters:
  • qubit1 (int): Index of the first state qubit.
  • qubit2 (int): Index of the second state qubit.
  • ancilla_qubit (int, default to 0): Index of the ancilla qubit.
• Usage: Convenience wrapper for fidelity/overlap measurement across backends.