squander::density::DepolarizingChannel Class Reference

Depolarizing channel: ρ → (1-p)ρ + p·I/2^n. More...

#include <noise_channel.h>

Inheritance diagram for squander::density::DepolarizingChannel:

Public Member Functions
void	apply (DensityMatrix &rho) override
	Apply noise channel to density matrix. More...
	DepolarizingChannel (int qbit_num, double error_rate)
	Constructor. More...
double	get_error_rate () const
std::string	get_name () const override
	Get channel name. More...
int	get_qbit_num () const

Private Attributes
double	error_rate_
int	qbit_num_

Detailed Description

Depolarizing channel: ρ → (1-p)ρ + p·I/2^n.

Represents uniform noise that replaces quantum state with maximally mixed state. Equivalent to applying X, Y, Z with equal probability p/3 each.

Kraus operators:

• K₀ = √(1-p) I
• K₁ = √(p/3) X
• K₂ = √(p/3) Y
• K₃ = √(p/3) Z

Example:

DepolarizingChannel noise(2, 0.01);  // 1% depolarizing noise
DensityMatrix rho(2);
noise.apply(rho);  // ρ → 0.99ρ + 0.01·I/4

Definition at line 66 of file noise_channel.h.

Constructor & Destructor Documentation

DepolarizingChannel()

squander::density::DepolarizingChannel::DepolarizingChannel	(	int	qbit_num,
		double	error_rate
	)

Constructor.

Parameters

qbit_num	Number of qubits (applies to full system)
error_rate	Error rate p ∈ [0, 1]

Exceptions

std::invalid_argument

if error_rate not in [0,1]

Definition at line 27 of file noise_channel.cpp.

Member Function Documentation

apply()

void squander::density::DepolarizingChannel::apply ( DensityMatrix &  rho )

overridevirtual

Apply noise channel to density matrix.

Parameters

rho	Density matrix (modified in-place)

Implements squander::density::NoiseChannel.

Definition at line 35 of file noise_channel.cpp.

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get_error_rate()

double squander::density::DepolarizingChannel::get_error_rate ( ) const

inline

Definition at line 79 of file noise_channel.h.

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get_name()

std::string squander::density::DepolarizingChannel::get_name ( ) const

inlineoverridevirtual

Get channel name.

Implements squander::density::NoiseChannel.

Definition at line 77 of file noise_channel.h.

get_qbit_num()

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

inline

Definition at line 80 of file noise_channel.h.

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Member Data Documentation

error_rate_

double squander::density::DepolarizingChannel::error_rate_

private

Definition at line 84 of file noise_channel.h.

qbit_num_

int squander::density::DepolarizingChannel::qbit_num_

private

Definition at line 83 of file noise_channel.h.

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

• noise_channel.h
• noise_channel.cpp