Quantum circuit with noise for density matrix simulation. More...

#include <noisy_circuit.h>

Classes
struct	OperationInfo
	Information about a circuit operation. More...

Public Member Functions
void	add_amplitude_damping (int target)
	Add parametric amplitude damping noise (1 parameter) More...

void	add_amplitude_damping (int target, double gamma)
	Add fixed amplitude damping noise (T1 relaxation, 0 parameters) More...

void	add_CH (int target, int control)

void	add_CNOT (int target, int control)

void	add_CP (int target, int control)
	1 parameter More...

void	add_CRX (int target, int control)
	1 parameter More...

void	add_CRY (int target, int control)
	1 parameter More...

void	add_CRZ (int target, int control)
	1 parameter More...

void	add_CZ (int target, int control)

void	add_depolarizing (int qbit_num)
	Add parametric depolarizing noise channel (1 parameter) More...

void	add_depolarizing (int qbit_num, double error_rate)
	Add fixed depolarizing noise channel (0 parameters) More...

void	add_H (int target)

void	add_local_depolarizing (int target)
	Add parametric local single-qubit depolarizing noise (1 parameter) More...

void	add_local_depolarizing (int target, double error_rate)
	Add fixed local single-qubit depolarizing noise (0 parameters) More...

void	add_phase_damping (int target)
	Add parametric phase damping noise (1 parameter) More...

void	add_phase_damping (int target, double lambda)
	Add fixed phase damping noise (T2 dephasing, 0 parameters) More...

void	add_RX (int target)
	1 parameter More...

void	add_RY (int target)
	1 parameter More...

void	add_RZ (int target)
	1 parameter More...

void	add_S (int target)

void	add_Sdg (int target)

void	add_SX (int target)

void	add_T (int target)

void	add_Tdg (int target)

void	add_U1 (int target)
	1 parameter More...

void	add_U2 (int target)
	2 parameters More...

void	add_U3 (int target)
	3 parameters More...

void	add_X (int target)

void	add_Y (int target)

void	add_Z (int target)

void	apply_to (const double *params, int param_count, DensityMatrix &rho)
	Apply entire circuit to density matrix. More...

void	apply_to (const matrix_base< double > &params, DensityMatrix &rho)
	Apply circuit using Matrix_real (backward compatibility) More...

size_t	get_operation_count () const
	Get number of operations in the circuit. More...

std::vector< OperationInfo >	get_operation_info () const
	Get information about all operations. More...

int	get_parameter_num () const
	Get total number of parameters needed. More...

int	get_qbit_num () const
	Get number of qubits. More...

	NoisyCircuit (int qbit_num)
	Create empty circuit for n qubits. More...

	NoisyCircuit (const NoisyCircuit &)=delete

	NoisyCircuit (NoisyCircuit &&other) noexcept

NoisyCircuit &	operator= (const NoisyCircuit &)=delete

NoisyCircuit &	operator= (NoisyCircuit &&other) noexcept

	~NoisyCircuit ()
	Destructor. More...

Private Member Functions
void	add_gate_internal (Gate *gate)

void	add_operation (std::unique_ptr< IDensityOperation > op)

Private Attributes
std::vector< std::unique_ptr< IDensityOperation > >	operations_

std::vector< int >	param_starts_

int	qbit_num_

int	total_params_ = 0

Detailed Description

Quantum circuit with noise for density matrix simulation.

NoisyCircuit manages a sequence of unitary gates and noise channels, providing a unified interface to build and execute noisy quantum circuits.

Key features:

Unified API for adding gates and noise channels
Optimized local kernel application (O(4^N) per gate instead of O(8^N))
Support for both fixed and parametric noise
Sequential execution (each operation applied in order)

Example:

NoisyCircuit circuit(2);
circuit.add_H(0);
circuit.add_CNOT(1, 0);
circuit.add_depolarizing(2, 0.01);  // Fixed 1% noise
circuit.add_RZ(0);                   // Parametric gate
circuit.add_phase_damping(0);        // Parametric noise
DensityMatrix rho(2);
std::vector<double> params = {0.5, 0.02};  // RZ angle, phase damping Î»
circuit.apply_to(params.data(), params.size(), rho);

Definition at line 57 of file noisy_circuit.h.

Constructor & Destructor Documentation

◆ NoisyCircuit() [1/3]

squander::density::NoisyCircuit::NoisyCircuit ( int qbit_num )

explicit

Create empty circuit for n qubits.

Parameters

qbit_num Number of qubits (must be >= 1)

Definition at line 52 of file noisy_circuit.cpp.

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◆ ~NoisyCircuit()

squander::density::NoisyCircuit::~NoisyCircuit ( )

default

Destructor.

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◆ NoisyCircuit() [2/3]

squander::density::NoisyCircuit::NoisyCircuit ( const NoisyCircuit & )

delete

◆ NoisyCircuit() [3/3]

squander::density::NoisyCircuit::NoisyCircuit ( NoisyCircuit && other )

noexcept

Definition at line 64 of file noisy_circuit.cpp.

Member Function Documentation

◆ add_amplitude_damping() [1/2]

void squander::density::NoisyCircuit::add_amplitude_damping ( int target )

Add parametric amplitude damping noise (1 parameter)

Parameters

target Target qubit index

Definition at line 225 of file noisy_circuit.cpp.

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◆ add_amplitude_damping() [2/2]

void squander::density::NoisyCircuit::add_amplitude_damping	(	int	target,
		double	gamma
	)

Add fixed amplitude damping noise (T1 relaxation, 0 parameters)

Parameters

target	Target qubit index
gamma	Fixed damping Î³ â [0,1]

Definition at line 230 of file noisy_circuit.cpp.

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◆ add_CH()

void squander::density::NoisyCircuit::add_CH	(	int	target,
		int	control
	)

Definition at line 178 of file noisy_circuit.cpp.

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◆ add_CNOT()

void squander::density::NoisyCircuit::add_CNOT	(	int	target,
		int	control
	)

Definition at line 170 of file noisy_circuit.cpp.

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◆ add_CP()

void squander::density::NoisyCircuit::add_CP	(	int	target,
		int	control
	)

1 parameter

Definition at line 198 of file noisy_circuit.cpp.

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◆ add_CRX()

void squander::density::NoisyCircuit::add_CRX	(	int	target,
		int	control
	)

1 parameter

Definition at line 194 of file noisy_circuit.cpp.

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◆ add_CRY()

void squander::density::NoisyCircuit::add_CRY	(	int	target,
		int	control
	)

1 parameter

Definition at line 186 of file noisy_circuit.cpp.

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◆ add_CRZ()

void squander::density::NoisyCircuit::add_CRZ	(	int	target,
		int	control
	)

1 parameter

Definition at line 190 of file noisy_circuit.cpp.

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◆ add_CZ()

void squander::density::NoisyCircuit::add_CZ	(	int	target,
		int	control
	)

Definition at line 174 of file noisy_circuit.cpp.

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◆ add_depolarizing() [1/2]

void squander::density::NoisyCircuit::add_depolarizing ( int qbit_num )

Add parametric depolarizing noise channel (1 parameter)

Parameters

qbit_num Number of qubits the noise acts on

Definition at line 206 of file noisy_circuit.cpp.

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◆ add_depolarizing() [2/2]

void squander::density::NoisyCircuit::add_depolarizing	(	int	qbit_num,
		double	error_rate
	)

Add fixed depolarizing noise channel (0 parameters)

Parameters

qbit_num	Number of qubits the noise acts on
error_rate	Fixed error rate p â [0,1]

Definition at line 210 of file noisy_circuit.cpp.

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◆ add_gate_internal()

void squander::density::NoisyCircuit::add_gate_internal ( Gate * gate )

private

Definition at line 94 of file noisy_circuit.cpp.

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◆ add_H()

void squander::density::NoisyCircuit::add_H ( int target )

Definition at line 102 of file noisy_circuit.cpp.

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◆ add_local_depolarizing() [1/2]

void squander::density::NoisyCircuit::add_local_depolarizing ( int target )

Add parametric local single-qubit depolarizing noise (1 parameter)

Parameters

target Target qubit index

Definition at line 215 of file noisy_circuit.cpp.

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◆ add_local_depolarizing() [2/2]

void squander::density::NoisyCircuit::add_local_depolarizing	(	int	target,
		double	error_rate
	)

Add fixed local single-qubit depolarizing noise (0 parameters)

Parameters

target	Target qubit index
error_rate	Fixed depolarizing strength p in [0,1]

Definition at line 220 of file noisy_circuit.cpp.

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◆ add_operation()

void squander::density::NoisyCircuit::add_operation ( std::unique_ptr< IDensityOperation > op )

private

Definition at line 88 of file noisy_circuit.cpp.

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◆ add_phase_damping() [1/2]

void squander::density::NoisyCircuit::add_phase_damping ( int target )

Add parametric phase damping noise (1 parameter)

Parameters

target Target qubit index

Definition at line 235 of file noisy_circuit.cpp.

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◆ add_phase_damping() [2/2]

void squander::density::NoisyCircuit::add_phase_damping	(	int	target,
		double	lambda
	)

Add fixed phase damping noise (T2 dephasing, 0 parameters)

Parameters

target	Target qubit index
lambda	Fixed dephasing Î» â [0,1]

Definition at line 239 of file noisy_circuit.cpp.

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◆ add_RX()

void squander::density::NoisyCircuit::add_RX ( int target )

1 parameter

Definition at line 142 of file noisy_circuit.cpp.

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◆ add_RY()

void squander::density::NoisyCircuit::add_RY ( int target )

1 parameter

Definition at line 146 of file noisy_circuit.cpp.

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◆ add_RZ()

void squander::density::NoisyCircuit::add_RZ ( int target )

1 parameter

Definition at line 150 of file noisy_circuit.cpp.

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◆ add_S()

void squander::density::NoisyCircuit::add_S ( int target )

Definition at line 118 of file noisy_circuit.cpp.

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◆ add_Sdg()

void squander::density::NoisyCircuit::add_Sdg ( int target )

Definition at line 122 of file noisy_circuit.cpp.

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◆ add_SX()

void squander::density::NoisyCircuit::add_SX ( int target )

Definition at line 134 of file noisy_circuit.cpp.

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◆ add_T()

void squander::density::NoisyCircuit::add_T ( int target )

Definition at line 126 of file noisy_circuit.cpp.

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◆ add_Tdg()

void squander::density::NoisyCircuit::add_Tdg ( int target )

Definition at line 130 of file noisy_circuit.cpp.

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◆ add_U1()

void squander::density::NoisyCircuit::add_U1 ( int target )

1 parameter

Definition at line 154 of file noisy_circuit.cpp.

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◆ add_U2()

void squander::density::NoisyCircuit::add_U2 ( int target )

2 parameters

Definition at line 158 of file noisy_circuit.cpp.

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◆ add_U3()

void squander::density::NoisyCircuit::add_U3 ( int target )

3 parameters

Definition at line 162 of file noisy_circuit.cpp.

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◆ add_X()

void squander::density::NoisyCircuit::add_X ( int target )

Definition at line 106 of file noisy_circuit.cpp.

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◆ add_Y()

void squander::density::NoisyCircuit::add_Y ( int target )

Definition at line 110 of file noisy_circuit.cpp.

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◆ add_Z()

void squander::density::NoisyCircuit::add_Z ( int target )

Definition at line 114 of file noisy_circuit.cpp.

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◆ apply_to() [1/2]

void squander::density::NoisyCircuit::apply_to	(	const double *	params,
		int	param_count,
		DensityMatrix &	rho
	)

Apply entire circuit to density matrix.

Parameters

params	Parameter array (gate params followed by noise params)
param_count	Total number of parameters
rho	Density matrix to modify in-place

Parameters are consumed in the order operations were added. Each parametric operation extracts its parameters from the array.

Definition at line 248 of file noisy_circuit.cpp.

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◆ apply_to() [2/2]

void squander::density::NoisyCircuit::apply_to	(	const matrix_base< double > &	params,
		DensityMatrix &	rho
	)

Apply circuit using Matrix_real (backward compatibility)

Definition at line 271 of file noisy_circuit.cpp.

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◆ get_operation_count()

size_t squander::density::NoisyCircuit::get_operation_count ( ) const

inline

Get number of operations in the circuit.

Definition at line 217 of file noisy_circuit.h.

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◆ get_operation_info()

std::vector< NoisyCircuit::OperationInfo > squander::density::NoisyCircuit::get_operation_info ( ) const

Get information about all operations.

Definition at line 281 of file noisy_circuit.cpp.

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◆ get_parameter_num()

int squander::density::NoisyCircuit::get_parameter_num ( ) const

inline

Get total number of parameters needed.

Definition at line 212 of file noisy_circuit.h.

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◆ get_qbit_num()

int squander::density::NoisyCircuit::get_qbit_num ( ) const

inline

Get number of qubits.

Definition at line 207 of file noisy_circuit.h.

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◆ operator=() [1/2]

NoisyCircuit& squander::density::NoisyCircuit::operator= ( const NoisyCircuit & )

delete

◆ operator=() [2/2]

NoisyCircuit & squander::density::NoisyCircuit::operator= ( NoisyCircuit && other )

noexcept

Definition at line 72 of file noisy_circuit.cpp.

Member Data Documentation

◆ operations_

std::vector<std::unique_ptr<IDensityOperation> > squander::density::NoisyCircuit::operations_

private

Definition at line 240 of file noisy_circuit.h.

◆ param_starts_

std::vector<int> squander::density::NoisyCircuit::param_starts_

private

Definition at line 241 of file noisy_circuit.h.

◆ qbit_num_

int squander::density::NoisyCircuit::qbit_num_

private

Definition at line 239 of file noisy_circuit.h.

◆ total_params_

int squander::density::NoisyCircuit::total_params_ = 0

private

Definition at line 242 of file noisy_circuit.h.

The documentation for this class was generated from the following files:

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ NoisyCircuit() [1/3]

◆ ~NoisyCircuit()

◆ NoisyCircuit() [2/3]

◆ NoisyCircuit() [3/3]

Member Function Documentation

◆ add_amplitude_damping() [1/2]

◆ add_amplitude_damping() [2/2]

◆ add_CH()

◆ add_CNOT()

◆ add_CP()

◆ add_CRX()

◆ add_CRY()

◆ add_CRZ()

◆ add_CZ()

◆ add_depolarizing() [1/2]

◆ add_depolarizing() [2/2]

◆ add_gate_internal()

◆ add_H()

◆ add_local_depolarizing() [1/2]

◆ add_local_depolarizing() [2/2]

◆ add_operation()

◆ add_phase_damping() [1/2]

◆ add_phase_damping() [2/2]

◆ add_RX()

◆ add_RY()

◆ add_RZ()

◆ add_S()

◆ add_Sdg()

◆ add_SX()

◆ add_T()

◆ add_Tdg()

◆ add_U1()

◆ add_U2()

◆ add_U3()

◆ add_X()

◆ add_Y()

◆ add_Z()

◆ apply_to() [1/2]

◆ apply_to() [2/2]

◆ get_operation_count()

◆ get_operation_info()

◆ get_parameter_num()

◆ get_qbit_num()

◆ operator=() [1/2]

◆ operator=() [2/2]

Member Data Documentation

◆ operations_

◆ param_starts_

◆ qbit_num_

◆ total_params_