Base class for time integration schemes to evolve the quantum dynamics. More...

#include <timestepper.hpp>

Inheritance diagram for TimeStepper:

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Collaboration diagram for TimeStepper:

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Public Member Functions
	TimeStepper ()

	TimeStepper (const Config &config, MasterEq mastereq_, Output output_, int ninit_local)
	Constructor for time stepper.

virtual	~TimeStepper ()

double	getLeakageIntegral ()

double	getWeightedCostIntegral ()

double	getEnergyIntegral ()

double	getDPDMIntegral ()

Vec	getReducedGradient ()

void	setWriteTrajectoryDataFiles (bool write)

void	setOptimTarget (OptimTarget *optim_target_)

Vec	getFinalState (size_t iinit_local)
	Retrieves the final state for a specific local initial condition.

virtual double	getMinTimestepSize () const
	Get the smallest timestep size used during timestepping.

virtual Vec	solveODE (int initid, int iinit_local, Vec rho_t0)
	Solves the ODE forward in time.

virtual void	solveAdjointODE (int iinit_local, Vec rho_t0_bar, double Jbar_leakage, double Jbar_weightedcost, double Jbar_dpdm, double Jbar_energy)
	Solves the adjoint ODE backward in time.

double	evalLeakage (const Vec x)
	Evaluates leakage into guard levels.

void	evalLeakage_diff (const Vec x, Vec xbar, double Jbar)
	Computes derivative of leakage term.

double	evalWeightedCost (double time, const Vec x)
	Evaluates the weighted cost function term.

void	evalWeightedCost_diff (double time, const Vec x, Vec xbar, double Jbar)
	Computes derivative of weighted cost function term.

double	evalDpDm (Vec x, Vec xm1, Vec xm2)
	Evaluates second-order derivative variation for the state.

void	evalDpDm_diff (int n, Vec xbar, double Jbar)
	Computes derivative of second-order derivative variation term.

double	evalEnergy (double time)
	Evaluates energy integral term.

void	evalEnergy_diff (double time, double Jbar, Vec redgrad)
	Computes derivative of energy integral.

virtual void	evolveFWD (const double tstart, const double tstop, Vec x)=0
	Evolves state forward by one time-step from tstart to tstop.

virtual void	evolveBWD (const double tstart, const double tstop, const Vec x_stop, Vec x_adj, Vec grad, bool compute_gradient)
	Evolves adjoint state backward by one time-step and updates reduced gradient.

Protected Attributes
Vec	x
	Auxiliary vector for forward time stepping.

Vec	xadj
	Auxiliary vector needed for adjoint (backward) time stepping.

Vec	xprimal
	Auxiliary vector for backward time stepping.

std::vector< std::vector< Vec > >	trajectory_states
	Storage for primal states during forward evolution, one trajectory for each local initial condition..

std::vector< Vec >	final_states
	Storage for final states for each local initial condition. Always filled after solveODE.

std::vector< Vec >	dpdm_states
	Storage for states needed for second-order derivative penalty.

int	mpirank_world
	MPI rank in global communicator.

int	mpisize_petsc
	MPI size in Petsc communicator.

int	mpirank_petsc
	MPI rank in Petsc 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	eval_leakage
	Flag to compute leakage integral term.

bool	eval_energy
	Flag to compute energy integral term.

bool	eval_dpdm
	Flag to compute second-order derivative integral term.

bool	eval_weightedcost
	Flag to compute weighted cost integral term.

double	leakage_integral
	Sums the integral over leakage.

double	energy_integral
	Sums the energy term.

double	dpdm_integral
	Sums second-order derivative variation value.

double	weightedcost_integral
	Sums the integral over weighted cost function.

double	weightedcost_width
	Width parameter for weighted cost function.

int	ntime
	Number of time steps.

double	total_time
	Final evolution time.

double	dt
	Time step size.

bool	writeTrajectoryDataFiles
	Flag to determine whether or not trajectory data will be written to files during forward simulation *‍/.

Vec	redgrad
	Reduced gradient vector for optimization.

OptimTarget *	optim_target
	Pointer to optimization target specification.

Output *	output
	Pointer to output handler.

MasterEq *	mastereq
	Pointer to master equation solver.

Detailed Description

Base class for time integration schemes to evolve the quantum dynamics.

This abstract class provides the interface for time-stepping methods used to integrate the quantum evolution equations (Lindblad master equation or Schroedinger equation). It supports both forward and adjoint time integration, handles output of evolution data, and evaluates penalty integral terms.

Main functionality:

solveODE propagates an initial state at time t0 to the final time T, while writing evolution data to files and adding to integral penalty terms, if needed.
solveAdjointODE propagates a terminal (adjoint) condition through the time domain backwards in time from T to 0, while updating the reduced gradient along the way.

This class contains references to:

MasterEq for evaluating and applying the right-hand-side system matrix of the real-valued, vectorized differential equation to a state vector at each time-step
OptimTarget for evaluating integral penalty terms at each time step
Output for writing evolution data to output files at each time step

Constructor & Destructor Documentation

◆ TimeStepper() [1/2]

TimeStepper::TimeStepper ( )

◆ TimeStepper() [2/2]

TimeStepper::TimeStepper	(	const Config &	config,
		MasterEq *	mastereq_,
		Output *	output_,
		int	ninit_local
	)

Constructor for time stepper.

Parameters

config	Configuration parameters from input file
mastereq_	Pointer to master equation solver
output_	Pointer to output handler
ninit_local	Number of initial conditions local to this processor

◆ ~TimeStepper()

TimeStepper::~TimeStepper ( )

virtual

Member Function Documentation

◆ evalDpDm()

double TimeStepper::evalDpDm	(	Vec	x,
		Vec	xm1,
		Vec	xm2
	)

Evaluates second-order derivative variation for the state.

Parameters

x	Current state vector
xm1	State vector at previous time step
xm2	State vector at two time steps ago

Returns: double Second-order variation value

◆ evalDpDm_diff()

void TimeStepper::evalDpDm_diff	(	int	n,
		Vec	xbar,
		double	Jbar
	)

Computes derivative of second-order derivative variation term.

Parameters

n	Time step index
xbar	Adjoint state vector to update
Jbar	Adjoint of dpdm term

◆ evalEnergy()

double TimeStepper::evalEnergy ( double time )

Evaluates energy integral term.

Parameters

time	Current time

Returns: double Energy value

◆ evalEnergy_diff()

void TimeStepper::evalEnergy_diff	(	double	time,
		double	Jbar,
		Vec	redgrad
	)

Computes derivative of energy integral.

Parameters

time	Current time
Jbar	Adjoint of energy
redgrad	Reduced gradient vector to update

◆ evalLeakage()

double TimeStepper::evalLeakage ( const Vec x )

Evaluates leakage into guard levels.

Parameters

x	Current state vector

Returns: double Leakage term value / ntime

◆ evalLeakage_diff()

void TimeStepper::evalLeakage_diff	(	const Vec	x,
		Vec	xbar,
		double	Jbar
	)

Computes derivative of leakage term.

Parameters

x	Current state vector
xbar	Adjoint state vector to update
Jbar	Adjoint of leakage integral term

◆ evalWeightedCost()

double TimeStepper::evalWeightedCost	(	double	time,
		const Vec	x
	)

Evaluates the weighted cost function term.

Parameters

time	Current time
x	Current state vector

Returns: double Weighted cost integral term value

◆ evalWeightedCost_diff()

void TimeStepper::evalWeightedCost_diff	(	double	time,
		const Vec	x,
		Vec	xbar,
		double	Jbar
	)

Computes derivative of weighted cost function term.

Parameters

time	Current time
x	Current state vector
xbar	Adjoint state vector to update
Jbar	Adjoint of weighted cost term

◆ evolveBWD()

void TimeStepper::evolveBWD	(	const double	tstart,
		const double	tstop,
		const Vec	x_stop,
		Vec	x_adj,
		Vec	grad,
		bool	compute_gradient
	)

virtual

Evolves adjoint state backward by one time-step and updates reduced gradient.

Abstract base-class implementation is empty. Derived classes that need backward time-stepping should implement this function.

Parameters

tstart	Start time (backward evolution)
tstop	Stop time (backward evolution)
x_stop	State at stop time
x_adj	Adjoint state vector
grad	Gradient vector to update
compute_gradient	Flag to compute gradient

Reimplemented in ExplEuler, ImplMidpoint, CompositionalImplMidpoint, and PetscTS.

◆ evolveFWD()

virtual void TimeStepper::evolveFWD	(	const double	tstart,
		const double	tstop,
		Vec	x
	)

pure virtual

Evolves state forward by one time-step from tstart to tstop.

Pure virtual function to be implemented by the derived time-stepping classes.

Parameters

tstart	Start time
tstop	Stop time
x	State vector to evolve

Implemented in ExplEuler, ImplMidpoint, CompositionalImplMidpoint, and PetscTS.

◆ getDPDMIntegral()

double TimeStepper::getDPDMIntegral ( )

inline

◆ getEnergyIntegral()

double TimeStepper::getEnergyIntegral ( )

inline

◆ getFinalState()

Vec TimeStepper::getFinalState ( size_t iinit_local )

inline

Retrieves the final state for a specific local initial condition.

Parameters

iinit_local Local index of the initial condition

Returns: Vec Final state vector for the specified initial condition

◆ getLeakageIntegral()

double TimeStepper::getLeakageIntegral ( )

inline

◆ getMinTimestepSize()

virtual double TimeStepper::getMinTimestepSize ( ) const

inlinevirtual

Get the smallest timestep size used during timestepping.

For adaptive timestepping methods, returns the minimum timestep size chosen. For fixed timestep methods, returns the regular timestep size (dt).

Returns: double Smallest timestep size

Reimplemented in PetscTS.

◆ getReducedGradient()

Vec TimeStepper::getReducedGradient ( )

inline

◆ getWeightedCostIntegral()

double TimeStepper::getWeightedCostIntegral ( )

inline

◆ setOptimTarget()

void TimeStepper::setOptimTarget ( OptimTarget * optim_target_ )

inline

◆ setWriteTrajectoryDataFiles()

void TimeStepper::setWriteTrajectoryDataFiles ( bool write )

inline

◆ solveAdjointODE()

void TimeStepper::solveAdjointODE	(	int	iinit_local,
		Vec	rho_t0_bar,
		double	Jbar_leakage,
		double	Jbar_weightedcost,
		double	Jbar_dpdm,
		double	Jbar_energy
	)

virtual

Solves the adjoint ODE backward in time.

This performs backward time-stepping to backpropagate an adjoint initial condition at final time (aka a terminal condtion) to time t=0, while accumulating the reduced gradient.

Parameters

iinit_local	Local index of initial condition for this processor
rho_t0_bar	Terminal condition for adjoint state
Jbar_leakage	Adjoint of leakage integral term
Jbar_weightedcost	Adjoint of weighted cost integral term
Jbar_dpdm	Adjoint of second-order derivative variation
Jbar_energy	Adjoint of energy integral term

Reimplemented in PetscTS.

◆ solveODE()

Vec TimeStepper::solveODE	(	int	initid,
		int	iinit_local,
		Vec	rho_t0
	)

virtual

Solves the ODE forward in time.

This performs the time-stepping to propagate an initial condition to the final time.

Parameters

initid	Initial condition identifier
iinit_local	Local index of initial condition for this processor
rho_t0	Initial state vector

Returns: Vec Final state vector at time T

Reimplemented in PetscTS.

Member Data Documentation

◆ dpdm_integral

double TimeStepper::dpdm_integral

protected

Sums second-order derivative variation value.

◆ dpdm_states

std::vector<Vec> TimeStepper::dpdm_states

protected

Storage for states needed for second-order derivative penalty.

◆ dt

double TimeStepper::dt

protected

Time step size.

◆ energy_integral

double TimeStepper::energy_integral

protected

Sums the energy term.

◆ eval_dpdm

bool TimeStepper::eval_dpdm

protected

Flag to compute second-order derivative integral term.

◆ eval_energy

bool TimeStepper::eval_energy

protected

Flag to compute energy integral term.

◆ eval_leakage

bool TimeStepper::eval_leakage

protected

Flag to compute leakage integral term.

◆ eval_weightedcost

bool TimeStepper::eval_weightedcost

protected

Flag to compute weighted cost integral term.

◆ final_states

std::vector<Vec> TimeStepper::final_states

protected

Storage for final states for each local initial condition. Always filled after solveODE.

◆ ilow

PetscInt TimeStepper::ilow

protected

First index of the local sub vector u,v.

◆ iupp

PetscInt TimeStepper::iupp

protected

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

◆ leakage_integral

double TimeStepper::leakage_integral

protected

Sums the integral over leakage.

◆ localsize_u

PetscInt TimeStepper::localsize_u

protected

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

◆ mastereq

MasterEq* TimeStepper::mastereq

protected

Pointer to master equation solver.

◆ mpirank_petsc

int TimeStepper::mpirank_petsc

protected

MPI rank in Petsc communicator.

◆ mpirank_world

int TimeStepper::mpirank_world

protected

MPI rank in global communicator.

◆ mpisize_petsc

int TimeStepper::mpisize_petsc

protected

MPI size in Petsc communicator.

◆ ntime

int TimeStepper::ntime

protected

Number of time steps.

◆ optim_target

OptimTarget* TimeStepper::optim_target

protected

Pointer to optimization target specification.

◆ output

Output* TimeStepper::output

protected

Pointer to output handler.

◆ redgrad

Vec TimeStepper::redgrad

protected

Reduced gradient vector for optimization.

◆ total_time

double TimeStepper::total_time

protected

Final evolution time.

◆ trajectory_states

std::vector<std::vector<Vec> > TimeStepper::trajectory_states

protected

Storage for primal states during forward evolution, one trajectory for each local initial condition..

◆ weightedcost_integral

double TimeStepper::weightedcost_integral

protected

Sums the integral over weighted cost function.

◆ weightedcost_width

double TimeStepper::weightedcost_width

protected

Width parameter for weighted cost function.

◆ writeTrajectoryDataFiles

bool TimeStepper::writeTrajectoryDataFiles

protected

Flag to determine whether or not trajectory data will be written to files during forward simulation *‍/.

◆ x

Vec TimeStepper::x

protected

Auxiliary vector for forward time stepping.

◆ xadj

Vec TimeStepper::xadj

protected

Auxiliary vector needed for adjoint (backward) time stepping.

◆ xprimal

Vec TimeStepper::xprimal

protected

Auxiliary vector for backward time stepping.

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

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

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ TimeStepper() [1/2]

◆ TimeStepper() [2/2]

◆ ~TimeStepper()

Member Function Documentation

◆ evalDpDm()

◆ evalDpDm_diff()

◆ evalEnergy()

◆ evalEnergy_diff()

◆ evalLeakage()

◆ evalLeakage_diff()

◆ evalWeightedCost()

◆ evalWeightedCost_diff()

◆ evolveBWD()

◆ evolveFWD()

◆ getDPDMIntegral()

◆ getEnergyIntegral()

◆ getFinalState()

◆ getLeakageIntegral()

◆ getMinTimestepSize()

◆ getReducedGradient()

◆ getWeightedCostIntegral()

◆ setOptimTarget()

◆ setWriteTrajectoryDataFiles()

◆ solveAdjointODE()

◆ solveODE()

Member Data Documentation

◆ dpdm_integral

◆ dpdm_states

◆ dt

◆ energy_integral

◆ eval_dpdm

◆ eval_energy

◆ eval_leakage

◆ eval_weightedcost

◆ final_states

◆ ilow

◆ iupp

◆ leakage_integral

◆ localsize_u

◆ mastereq

◆ mpirank_petsc

◆ mpirank_world

◆ mpisize_petsc

◆ ntime

◆ optim_target

◆ output

◆ redgrad

◆ total_time

◆ trajectory_states

◆ weightedcost_integral

◆ weightedcost_width

◆ writeTrajectoryDataFiles

◆ x

◆ xadj

◆ xprimal