squander::density::PhaseDampingChannel Class Reference

Phase damping (T2 dephasing): loss of coherence. More...

#include <noise_channel.h>

Inheritance diagram for squander::density::PhaseDampingChannel:

Public Member Functions
void	apply (DensityMatrix &rho) override
	Apply noise channel to density matrix. More...
double	get_lambda () const
std::string	get_name () const override
	Get channel name. More...
int	get_target_qbit () const
	PhaseDampingChannel (int target_qbit, double lambda)
	Constructor. More...

Private Attributes
double	lambda_
	λ = 1 - exp(-t/T2) More...
int	target_qbit_

Detailed Description

Phase damping (T2 dephasing): loss of coherence.

Models phase randomization without energy loss. Represents decoherence in real quantum systems.

Kraus operators:

• K₀ = [[1, 0], [0, √(1-λ)]]
• K₁ = [[0, 0], [0, √λ]]

where λ = 1 - exp(-t/T2)

Example:

PhaseDampingChannel t2_noise(0, 0.03);  // 3% phase damping on qubit 0
DensityMatrix rho(2);
t2_noise.apply(rho);

Definition at line 145 of file noise_channel.h.

Constructor & Destructor Documentation

PhaseDampingChannel()

squander::density::PhaseDampingChannel::PhaseDampingChannel	(	int	target_qbit,
		double	lambda
	)

Constructor.

Parameters

target_qbit	Target qubit index
lambda	Dephasing parameter λ = 1 - exp(-t/T2) ∈ [0, 1]

Exceptions

std::invalid_argument

if lambda not in [0,1]

Definition at line 132 of file noise_channel.cpp.

Member Function Documentation

apply()

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

overridevirtual

Apply noise channel to density matrix.

Parameters

rho	Density matrix (modified in-place)

Implements squander::density::NoiseChannel.

Definition at line 139 of file noise_channel.cpp.

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get_lambda()

double squander::density::PhaseDampingChannel::get_lambda ( ) const

inline

Definition at line 158 of file noise_channel.h.

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get_name()

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

inlineoverridevirtual

Get channel name.

Implements squander::density::NoiseChannel.

Definition at line 156 of file noise_channel.h.

get_target_qbit()

int squander::density::PhaseDampingChannel::get_target_qbit ( ) const

inline

Definition at line 159 of file noise_channel.h.

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Member Data Documentation

lambda_

double squander::density::PhaseDampingChannel::lambda_

private

λ = 1 - exp(-t/T2)

Definition at line 163 of file noise_channel.h.

target_qbit_

int squander::density::PhaseDampingChannel::target_qbit_

private

Definition at line 162 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