Quantum oscillator (multi-level qubit) with control capabilities. More...

#include <oscillator.hpp>

Public Member Functions
	Oscillator ()

	Oscillator (const Config &config, size_t id, std::mt19937 rand_engine, int param_offset, bool quietmode)
	Constructor with simplified configuration-based specification.

virtual	~Oscillator ()

size_t	getNParams ()
	Retrieves the number of control parameters.

size_t	getNLevels ()
	Retrieves the number of energy levels.

double	getSelfkerr ()
	Retrieves the self-Kerr coefficient.

double	getDetuning ()
	Retrieves the detuning frequency.

double	getDecayTime ()
	Retrieves the T1 decay time.

double	getDephaseTime ()
	Retrieves the T2 dephasing time.

size_t	getNParameterizations ()
	Retrieves the number of control parameterizations in this oscillator (currently always 1).

size_t	getNCarrierfrequencies ()
	Retrieves the number of carrier frequencies.

ControlType	getControlType ()
	Retrieves the type of control parameterization.

int	getNSplines ()
	Retrieves the number of splines used in the control parameterization.

double	getRotFreq ()
	Retrieves the rotating frame frequency.

int	getNSegParams (int parameterizationID)
	Retrieves the number of parameters for a specific parameterization.

void	setParams (const double *x)
	Sets control parameters from a global storage.

void	getParams (double *x)
	Retrieves control parameters into a global storage.

void	clearParams ()
	Clears all control parameters.

int	evalControl (const double t, double Re_ptr, double Im_ptr)
	Evaluates the rotating-frame control functions.

int	evalControl_diff (const double t, double *grad_for_this_oscillator, const double pbar, const double qbar)
	Computes derivatives of control functions p(t) and q(t) with respect to the parameters.

int	evalControl_Labframe (const double t, double *f_ptr)
	Evaluates lab-frame control function.

double	expectedEnergy (const Vec x)
	Computes expected energy for this oscillator.

void	expectedEnergy_diff (const Vec x, Vec x_bar, const double obj_bar)
	Computes derivative of expected energy computation.

void	population (const Vec x, std::vector< double > &pop)
	Computes population in each energy level of this oscillator.

double	evalControlVariation ()
	Evaluates control variation penalty term.

void	evalControlVariationDiff (Vec G, double var_reg_bar, int skip_to_oscillator)
	Computes derivative of control variation penalty.

Public Attributes
PetscInt	dim_preOsc
	Dimension of coupled subsystems preceding this oscillator.

PetscInt	dim_postOsc
	Dimension of coupled subsystems following this oscillator.

Protected Attributes
int	myid
	Integer identifier for this oscillator.

size_t	nlevels
	Number of energy levels for this oscillator.

double	ground_freq
	Fundamental 0-1 transition frequency of this oscillator \(\omega_k\).

double	selfkerr
	Self-Kerr frequency \(\xi_k\), multiplies \(a_k^\dagger a_k^\dagger a_k a_k\).

double	detuning_freq
	Detuning frequency, detuning = ground_freq - rotational_freq, multiplies \(a_k^\dagger a_k\).

DecoherenceType	decoherence_type
	Type of Lindblad decoherence operators to include.

double	decay_time
	Characteristic time for T1 decay operations.

double	dephase_time
	Characteristic time for T2 dephasing operations.

std::vector< double >	params
	Control parameters for this oscillator.

double	Tfinal
	Final evolution time.

std::vector< ControlBasis * >	basisfunctions
	Basis functions for control parameterization foreach time parameterization. Note: Currently only one parameterization is supported!

std::vector< double >	carrier_freq
	Frequencies of the carrier waves.

int	mpirank_world
	Rank of MPI_COMM_WORLD.

int	mpirank_petsc
	Rank of PETSc's communicator.

int	mpisize_petsc
	Size of PETSc's communicator.

PetscInt	localsize_u
	Size of local sub vector u or v in state x=[u,v].

PetscInt	ilow
	First index of the local sub vector u,v.

PetscInt	iupp
	Last index (+1) of the local sub vector u,v.

bool	control_zero_boundary_condition
	Flag to enforce boundary conditions on controls.

Detailed Description

Quantum oscillator (multi-level qubit) with control capabilities.

This class represents a single quantum oscillator that is controlled by external control pulses. It stores the oscillator parameters, such as number of energy levels, frequency detuning, anharmonicity and Lindblad decay and dephasing times.
It also manages this oscillator's control pulse parameterization and carrier wave frequencies.

Main functionality:

evalControl computes the rotating-frame pulses p(t) & q(t) at a given time t. Those pulses are products of fixed-frequency carrier waves multiplied with an outer envelop (spline) whose shape is defined through the control parameters (params) and their corresponding basis functions defined in the ControlBasis.
expectedEnergy and population for computing this oscillators expected Energy and level occupations given a current state
evalControlVariation for evaluating control parameter variations used as penalty term in the optimization

This class contains references to:

Vector of ControlBasis for evaluating the oscillators control pulse envelop (e.g. Bspline) at a given time t

Constructor & Destructor Documentation

◆ Oscillator() [1/2]

Oscillator::Oscillator ( )

◆ Oscillator() [2/2]

Oscillator::Oscillator	(	const Config &	config,
		size_t	id,
		std::mt19937	rand_engine,
		int	param_offset,
		bool	quietmode
	)

Constructor with simplified configuration-based specification.

Parameters

config	Configuration parameters containing all oscillator settings
id	Oscillator identifier
rand_engine	Random number generator engine
param_offset	Offset for global control parameter indexing
quietmode	Flag for quiet mode operation

◆ ~Oscillator()

Oscillator::~Oscillator ( )

virtual

Member Function Documentation

◆ clearParams()

void Oscillator::clearParams ( )

inline

Clears all control parameters.

Makes this oscillator non-controllable by removing all parameters.

◆ evalControl()

int Oscillator::evalControl	(	const double	t,
		double *	Re_ptr,
		double *	Im_ptr
	)

Evaluates the rotating-frame control functions.

Computes the real and imaginary parts of the control function: Re = p(t), Im = q(t)

Parameters

[in]	t	Time at which to evaluate
[out]	Re_ptr	Pointer to store real part p(t)
[out]	Im_ptr	Pointer to store imaginary part q(t)

Returns: int Error code

◆ evalControl_diff()

int Oscillator::evalControl_diff	(	const double	t,
		double *	grad_for_this_oscillator,
		const double	pbar,
		const double	qbar
	)

Computes derivatives of control functions p(t) and q(t) with respect to the parameters.

Parameters

[in]	t	Time at which to evaluate derivatives
[out]	grad_for_this_oscillator	Array to update the gradient
[in]	pbar	Adjoint scaling factor for the gradient of p (seed)
[in]	qbar	Adjoint scaling factor for the gradient of q (seed)

Returns: int Error code

◆ evalControl_Labframe()

int Oscillator::evalControl_Labframe	(	const double	t,
		double *	f_ptr
	)

Evaluates lab-frame control function.

Parameters

t	Time at which to evaluate
f_ptr	Pointer to store lab-frame control value

Returns: int Error code

◆ evalControlVariation()

double Oscillator::evalControlVariation ( )

Evaluates control variation penalty term.

Computes finite-difference based regularization of control parameters.

Returns: double Control variation penalty value

◆ evalControlVariationDiff()

void Oscillator::evalControlVariationDiff	(	Vec	G,
		double	var_reg_bar,
		int	skip_to_oscillator
	)

Computes derivative of control variation penalty.

Parameters

G	Gradient vector to update
var_reg_bar	Adjoint of variation penalty
skip_to_oscillator	Offset to this oscillator's parameters in global vector

◆ expectedEnergy()

double Oscillator::expectedEnergy ( const Vec x )

Computes expected energy for this oscillator.

Returns the expected value of the number operator for this oscillator's subsystem.

Parameters

x	State vector

Returns: double Expected energy value

◆ expectedEnergy_diff()

void Oscillator::expectedEnergy_diff	(	const Vec	x,
		Vec	x_bar,
		const double	obj_bar
	)

Computes derivative of expected energy computation.

Parameters

x	State vector
x_bar	Adjoint state vector to update
obj_bar	Adjoint of expected energy

◆ getControlType()

ControlType Oscillator::getControlType ( )

inline

Retrieves the type of control parameterization.

Returns: ControlType Type of control parameterization

◆ getDecayTime()

double Oscillator::getDecayTime ( )

inline

Retrieves the T1 decay time.

Returns: double Decay time

◆ getDephaseTime()

double Oscillator::getDephaseTime ( )

inline

Retrieves the T2 dephasing time.

Returns: double Dephasing time

◆ getDetuning()

double Oscillator::getDetuning ( )

inline

Retrieves the detuning frequency.

Returns: double Detuning frequency (rad/time)

◆ getNCarrierfrequencies()

size_t Oscillator::getNCarrierfrequencies ( )

inline

Retrieves the number of carrier frequencies.

Returns: size_t Number of carrier frequencies

◆ getNLevels()

size_t Oscillator::getNLevels ( )

inline

Retrieves the number of energy levels.

Returns: size_t Number of energy levels

◆ getNParameterizations()

size_t Oscillator::getNParameterizations ( )

inline

Retrieves the number of control parameterizations in this oscillator (currently always 1).

Returns: size_t Number of time parameterizations (currently always returns 1)

◆ getNParams()

size_t Oscillator::getNParams ( )

inline

Retrieves the number of control parameters.

Returns: size_t Number of control parameters

◆ getNSegParams()

int Oscillator::getNSegParams ( int parameterizationID )

Retrieves the number of parameters for a specific parameterization.

Parameters

parameterizationID Segment identifier // Currently always 0!

Returns: int Number of parameters for this parameterization

◆ getNSplines()

int Oscillator::getNSplines ( )

inline

Retrieves the number of splines used in the control parameterization.

Returns: int Number of splines

◆ getParams()

void Oscillator::getParams ( double * x )

Retrieves control parameters into a global storage.

Parameters

x	Array to store control parameter values

◆ getRotFreq()

double Oscillator::getRotFreq ( )

inline

Retrieves the rotating frame frequency.

Returns: double Rotating frame frequency (Hz)

◆ getSelfkerr()

double Oscillator::getSelfkerr ( )

inline

Retrieves the self-Kerr coefficient.

Returns: double Self-Kerr frequency

◆ population()

void Oscillator::population	(	const Vec	x,
		std::vector< double > &	pop
	)

Computes population in each energy level of this oscillator.

Extracts the diagonal elements of the reduced density matrix for this oscillator.

Parameters

x	State vector
pop	Reference to vector to store population values

◆ setParams()

void Oscillator::setParams ( const double * x )

Sets control parameters from a global storage.

Parameters

x	Array of control parameter values

Member Data Documentation

◆ basisfunctions

std::vector<ControlBasis *> Oscillator::basisfunctions

protected

Basis functions for control parameterization foreach time parameterization. Note: Currently only one parameterization is supported!

◆ carrier_freq

std::vector<double> Oscillator::carrier_freq

protected

Frequencies of the carrier waves.

◆ control_zero_boundary_condition

bool Oscillator::control_zero_boundary_condition

protected

Flag to enforce boundary conditions on controls.

◆ decay_time

double Oscillator::decay_time

protected

Characteristic time for T1 decay operations.

◆ decoherence_type

DecoherenceType Oscillator::decoherence_type

protected

Type of Lindblad decoherence operators to include.

◆ dephase_time

double Oscillator::dephase_time

protected

Characteristic time for T2 dephasing operations.

◆ detuning_freq

double Oscillator::detuning_freq

protected

Detuning frequency, detuning = ground_freq - rotational_freq, multiplies \(a_k^\dagger a_k\).

◆ dim_postOsc

PetscInt Oscillator::dim_postOsc

Dimension of coupled subsystems following this oscillator.

◆ dim_preOsc

PetscInt Oscillator::dim_preOsc

Dimension of coupled subsystems preceding this oscillator.

◆ ground_freq

double Oscillator::ground_freq

protected

Fundamental 0-1 transition frequency of this oscillator \(\omega_k\).

◆ ilow

PetscInt Oscillator::ilow

protected

First index of the local sub vector u,v.

◆ iupp

PetscInt Oscillator::iupp

protected

Last index (+1) of the local sub vector u,v.

◆ localsize_u

PetscInt Oscillator::localsize_u

protected

Size of local sub vector u or v in state x=[u,v].

◆ mpirank_petsc

int Oscillator::mpirank_petsc

protected

Rank of PETSc's communicator.

◆ mpirank_world

int Oscillator::mpirank_world

protected

Rank of MPI_COMM_WORLD.

◆ mpisize_petsc

int Oscillator::mpisize_petsc

protected

Size of PETSc's communicator.

◆ myid

int Oscillator::myid

protected

Integer identifier for this oscillator.

◆ nlevels

size_t Oscillator::nlevels

protected

Number of energy levels for this oscillator.

◆ params

std::vector<double> Oscillator::params

protected

Control parameters for this oscillator.

◆ selfkerr

double Oscillator::selfkerr

protected

Self-Kerr frequency \(\xi_k\), multiplies \(a_k^\dagger a_k^\dagger a_k a_k\).

◆ Tfinal

double Oscillator::Tfinal

protected

Final evolution time.

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

/home/runner/work/quandary/quandary/include/oscillator.hpp
/home/runner/work/quandary/quandary/src/oscillator.cpp

Public Member Functions

Public Attributes

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Oscillator() [1/2]

◆ Oscillator() [2/2]

◆ ~Oscillator()

Member Function Documentation

◆ clearParams()

◆ evalControl()

◆ evalControl_diff()

◆ evalControl_Labframe()

◆ evalControlVariation()

◆ evalControlVariationDiff()

◆ expectedEnergy()

◆ expectedEnergy_diff()

◆ getControlType()

◆ getDecayTime()

◆ getDephaseTime()

◆ getDetuning()

◆ getNCarrierfrequencies()

◆ getNLevels()

◆ getNParameterizations()

◆ getNParams()

◆ getNSegParams()

◆ getNSplines()

◆ getParams()

◆ getRotFreq()

◆ getSelfkerr()

◆ population()

◆ setParams()

Member Data Documentation

◆ basisfunctions

◆ carrier_freq

◆ control_zero_boundary_condition

◆ decay_time

◆ decoherence_type

◆ dephase_time

◆ detuning_freq

◆ dim_postOsc

◆ dim_preOsc

◆ ground_freq

◆ ilow

◆ iupp

◆ localsize_u

◆ mpirank_petsc

◆ mpirank_world

◆ mpisize_petsc

◆ myid

◆ nlevels

◆ params

◆ selfkerr

◆ Tfinal