Implements a single Monte Carlo wave-function trajectory. More...

#include <MCWF_Trajectory.h>

Inheritance diagram for quantumtrajectory::MCWF_Trajectory< RANK >:

Collaboration diagram for quantumtrajectory::MCWF_Trajectory< RANK >:

Public Types
typedef structure::Exact< RANK >	Exact

typedef structure::Hamiltonian< RANK >	Hamiltonian

typedef structure::Liouvillean< RANK >	Liouvillean

typedef structure::Averaged< RANK >	Averaged

typedef quantumdata::StateVector< RANK >	StateVector

typedef StateVector::StateVectorLow	StateVectorLow

Public Types inherited from trajectory::Adaptive< quantumdata::Types< RANK >::StateVectorLow >
typedef evolved::Evolved< quantumdata::Types< RANK >::StateVectorLow >	Evolved

Public Member Functions
template<typename SYS >
	MCWF_Trajectory (StateVector &psi, const SYS &sys, const mcwf::Pars &p, const StateVectorLow &scaleAbs=StateVectorLow())
	Templated constructor with the same idea as Master::Master. More...

void	derivs (double, const StateVectorLow &, StateVectorLow &) const
	The actual function calculating the time derivative for ODE evolution. More...

Getters
const StateVector &	getPsi () const

const mcwf::Logger &	getLogger () const

Public Member Functions inherited from trajectory::Adaptive< quantumdata::Types< RANK >::StateVectorLow >
void	step (double deltaT)
	corresponding to Evolved::step, it takes a single adaptive step More...

Public Member Functions inherited from trajectory::AdaptiveIO< quantumdata::Types< RANK >::StateVectorLow >
	AdaptiveIO (Ptr)

cpputils::iarchive &	readState (cpputils::iarchive &iar)
	Read in the EvolvedIO from a cpputils::iarchive. More...

cpputils::oarchive &	writeState (cpputils::oarchive &oar) const
	Write the EvolvedIO to a cpputils::oarchive.

double	getTime () const
	Returns the time of the underlying EvolvedIO.

Public Member Functions inherited from trajectory::Trajectory
void	evolve (double deltaT)
	Propagation for a time interval of exactly deltaT.

std::ostream &	display (std::ostream &, int precision) const
	Displays a limited set of relevant physical and numerical information about the actual state of Trajectory at the actual time instant. More...

std::ostream &	displayParameters (std::ostream &os) const
	print header

std::ostream &	logOnEnd (std::ostream &os) const
	print a log at the end summarizing overall (e.g. time-averaged) physical and numerical data during the run

double	getTime () const
	actual time instant

double	getDtDid () const
	last perfomed timestep

cpputils::iarchive &	readState (cpputils::iarchive &iar)
	read from an archive

cpputils::oarchive &	writeState (cpputils::oarchive &oar) const
	write to an archive

Public Member Functions inherited from trajectory::Averageable< const quantumdata::StateVector< RANK > & >
const const quantumdata::StateVector< RANK > &	toBeAveraged () const
	returns the set of quantities condensed in a variable of type `T` that are “to be averaged”

Protected Member Functions
std::ostream &	display_v (std::ostream &, int) const override
	Forwards to structure::Averaged::display.

std::ostream &	displayKey_v (std::ostream &, size_t &) const override
	Forwards to structure::Averaged::displayKey.

cpputils::iarchive &	readStateMore_v (cpputils::iarchive &iar) override
	Forwards to QuantumTrajectory::readStateMore_v (that involves setting `t0`) + serializes mcwf::Logger state.

cpputils::oarchive &	writeStateMore_v (cpputils::oarchive &oar) const override
	Forwards to Base::writeStateMore_v + serializes mcwf::Logger state.

std::ostream &	logOnEnd_v (std::ostream &os) const override
	calls mcwf::Logger::onEnd

Protected Member Functions inherited from quantumtrajectory::QuantumTrajectory< RANK, trajectory::Stochastic< quantumdata::Types< RANK >::StateVectorLow, const quantumdata::StateVector< RANK > & > >
	QuantumTrajectory (typename structure::QuantumSystem< RANK >::Ptr qs, bool isNoisy, ArgumentPack &&...argumentPack)
	Constructor forwarding to `BASE` and QuantumSystemWrapper.

const QuantumSystemWrapper	getQSW () const

cpputils::iarchive &	readStateMore_v (cpputils::iarchive &iar) override
	Forwards to `BASE`, but also sets `t0`.

double	getT0 () const
	The time instant of the beginning of the current time step. More...

void	setT0 (double t0) const
	The time instant of the beginning of the current time step. More...

void	setT0 () const
	The time instant of the beginning of the current time step. Sets to the current time.

void	checkDimension (const CONSTRUCT &construct) const
	Check the dimensions of the stored quantum system against `construct` More...

Protected Member Functions inherited from trajectory::Stochastic< quantumdata::Types< RANK >::StateVectorLow, const quantumdata::StateVector< RANK > & >
std::ostream &	displayParameters_v (std::ostream &) const override

	Stochastic (quantumdata::Types< RANK >::StateVectorLow &, typename Evolved::Derivs, double dtInit, double epsRel, double epsAbs, const quantumdata::Types< RANK >::StateVectorLow &scaleAbs, const evolved::Maker< quantumdata::Types< RANK >::StateVectorLow > &, unsigned long seed, bool noise, const randomized::Maker &)
	Straightforward constructor combining the construction of Adaptive and randomized::Randomized.

	Stochastic (quantumdata::Types< RANK >::StateVectorLow &, typename Evolved::Derivs, double dtInit, const quantumdata::Types< RANK >::StateVectorLow &scaleAbs, const ParsStochastic &, const evolved::Maker< quantumdata::Types< RANK >::StateVectorLow > &, const randomized::Maker &)

const RandomizedPtr	getRandomized () const

bool	isNoisy () const

cpputils::oarchive &	writeStateMore_v (cpputils::oarchive &oar) const override
	hook into Trajectory::writeState

Protected Member Functions inherited from trajectory::Adaptive< quantumdata::Types< RANK >::StateVectorLow >
	Adaptive (quantumdata::Types< RANK >::StateVectorLow &, typename Evolved::Derivs, double, double, double, const quantumdata::Types< RANK >::StateVectorLow &, const evolved::Maker< quantumdata::Types< RANK >::StateVectorLow > &)
	Constructor taking the same parameters as needed to operate evolved::Maker.

	Adaptive (quantumdata::Types< RANK >::StateVectorLow &, typename Evolved::Derivs, double, const ParsEvolved &, const quantumdata::Types< RANK >::StateVectorLow &, const evolved::Maker< quantumdata::Types< RANK >::StateVectorLow > &)

const std::string	trajectoryID () const
	redirected to a pure virtual, this is needed for serialization of trajectory metadata

std::ostream &	displayParameters_v (std::ostream &) const override

const ConstPtr	getEvolved () const

const Ptr	getEvolved ()

double	getDtTry () const

Protected Member Functions inherited from trajectory::AdaptiveIO< quantumdata::Types< RANK >::StateVectorLow >
const Ptr	getEvolvedIO () const
	note: not the same const-correctness as in Adaptive

Additional Inherited Members
Protected Types inherited from quantumtrajectory::QuantumTrajectory< RANK, trajectory::Stochastic< quantumdata::Types< RANK >::StateVectorLow, const quantumdata::StateVector< RANK > & > >
typedef structure::QuantumSystemWrapper< RANK, true >	QuantumSystemWrapper

Protected Types inherited from trajectory::Adaptive< quantumdata::Types< RANK >::StateVectorLow >
typedef Evolved::ConstPtr	ConstPtr

typedef Evolved::Ptr	Ptr

Protected Attributes inherited from trajectory::AdaptiveIO< quantumdata::Types< RANK >::StateVectorLow >
SerializationMetadata	meta_

Related Functions inherited from trajectory::Trajectory
void	run (Trajectory &trajectory, double time, double deltaT, unsigned sdf, const std::string &ofn, const std::string &initialFileName, int precision, bool displayInfo, bool firstStateDisplay, double autoStopEpsilon, unsigned autoStopRepetition, const std::string &parsedCommandLine)
	Running in deltaT mode (displays in equal time intervals) for a certain time. More...

void	run (Trajectory &, long nDt, double deltaT, unsigned sdf, const std::string &ofn, const std::string &initialFileName, int precision, bool displayInfo, bool firstStateDisplay, double autoStopEpsilon, unsigned autoStopRepetition, const std::string &parsedCommandLine)
	Same as above but runs for a certain number of time intervals deltaT. More...

void	run (Trajectory &, const ParsRun &p)
	Dispatcher. More...

Detailed Description

template<int RANK>
class quantumtrajectory::MCWF_Trajectory< RANK >

Implements a single Monte Carlo wave-function trajectory.

In the framework, a single Monte Carlo wave-function step at time $t$ (at which point, if the system inherits from structure::Exact, the Schrödinger- and interaction pictures coincide) is implemented as a sequence of the following stages:

Coherent time development is applied:
1. If the system time evolution has Hamiltonian part, it is evolved with an adaptive-size step (cf. evolved::Evolved). This takes the system into $t+\Delta t$ .
2. The exact part (if any) of the time evolution is applied, making that the Schrödinger and interaction pictures coincide again at $t+\Delta t$ .
3. The state vector is renormalized.
If the system is not Liouvillean, the timestep ends here, reducing to a simple ODE evolution. Otherwise:
1. The rates (probabilities per unit time) corresponding to all jump operators are calculated. If some rates are found negative (“special jump”, cf. explanation at structure::Liouvillean::probabilities, then $J_\text{at}\ket\Psi$ is calculated (and tabulated) instead, and the rate is calculated as $\delta r_\text{at}=\norm{J_\text{at}\ket\Psi}^2$ .
  See also
  The notion of “special jumps” in the framework
2. First, it is verified whether the total jump probability is not too big. This is performed on two levels:
  1. The total jump rate $\delta r$ is calculated.
  2. If $\delta r\delta t>\delta p_\text{limit}'$ , the step is retraced: both the state vector and the state of the ODE stepper are restored to cached values at the beginning of the timestep, and phase I. is performed anew with a smaller stepsize $\delta p_\text{limit}/\delta r$ . With this, we ensure that $\delta p_\text{limit}$ (the parameter mcwf::Pars::dpLimit) is likely not to be overshot in the next try.
    Note
    It is assumed that $\delta p_\text{limit}'>\delta p_\text{limit}$ , their ratio being a parameter (mcwf::Pars::overshootTolerance) of the MCWF stepper.
  3. If just $\delta r\delta t_\text{next}>\delta p_\text{limit}$ (where $\Delta t_\text{next}$ is a guess for the next timestep given by the ODE stepper), the coherent step is accepted, but the timestep to try next is modified, to reduce the likeliness of overshoot: $\delta t_\text{next}\longrightarrow\delta p_\text{limit}/\delta r$ .
    See also
    The discussion at Sec. An adaptive MCWF method.
3. After a successful coherent step resulting in an acceptable $\delta r$ , the possible occurence of a quantum jump is considered: It is randomly decided which (if any) of the jumps to perform. If it is found to be a special jump, then the tabulated $J_\text{at}\ket\Psi$ is taken.

Template Parameters

RANK	arity of the Hilbert space

Note: In phase 2.b.ii, another approach would be not to trace back the whole step, but make a coherent step backwards to an intermediate time instant found by linear interpolation. This has several drawbacks, however, the most significant being that in the ODE stepper, it is not clear what to take as the timestep to try at the point when the direction of time is reversed. (Although in evolved::Evolved it is simply taken to be the timestep done in the last step…)

Todo:: factor out template-parameter independent code

Definition at line 60 of file MCWF_Trajectory.h.

Constructor & Destructor Documentation

template<int RANK>

template<typename SYS >

quantumtrajectory::MCWF_Trajectory< RANK >::MCWF_Trajectory	(	StateVector &	psi,
		const SYS &	sys,
		const mcwf::Pars &	p,
		const StateVectorLow &	scaleAbs = `StateVectorLow()`
	)

Templated constructor with the same idea as Master::Master.

Template Parameters

SYS	the physical system – can be any type convertible to structure::QuantumSystem::Ptr via cpputils::sharedPointerize

Parameters

psi	the state vector to be evolved
sys	object representing the quantum system
p	parameters of the evolution
scaleAbs	has the same role as `scaleAbs` in Master::Master

Member Function Documentation

template<int RANK>

void quantumtrajectory::MCWF_Trajectory< RANK >::derivs	(	double	,
		const StateVectorLow &	,
		StateVectorLow &
	)		const

The actual function calculating the time derivative for ODE evolution.

Implemented via structure::Hamiltonian::addContribution

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

quantumtrajectory/MCWF_Trajectory.h

Public Types

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

template<int RANK> class quantumtrajectory::MCWF_Trajectory< RANK >

Constructor & Destructor Documentation

Member Function Documentation

template<int RANK>
class quantumtrajectory::MCWF_Trajectory< RANK >