MasterEq Class Reference

Implementation of the real-valued right-hand-side (RHS) system matrix of the quantum dynamical equations. More...

#include <mastereq.hpp>

Collaboration diagram for MasterEq:

Public Member Functions
	MasterEq ()
	MasterEq (const Config &config, Oscillator **oscil_vec_, bool quietmode=false)
	Constructor with simplified configuration-based specification.
	~MasterEq ()
void	set_RHS_MatMult_operation ()
	Pass MatMult operations for applying the RHS to PETSc.
void	initSparseMatSolver ()
	Initializes matrices needed for the sparse matrix solver.
Oscillator *	getOscillator (const size_t i)
	Retrieves the i-th oscillator.
size_t	getNOscillators ()
	Retrieves the number of oscillators in the system.
PetscInt	getDim ()
	Retrieves the dimension of the vectorized system.
PetscInt	getDimEss ()
	Retrieves the dimension of the essential level system.
PetscInt	getDimRho ()
	Retrieves the dimension of the density matrix.
int	assemble_RHS (const double t)
	Assembles the real-valued system matrix (RHS) at time t.
Mat	getRHS ()
	Retrieves the right-hand-side system matrix.
void	compute_dRHS_dParams (const double t, const Vec x, const Vec x_bar, const double alpha, Vec grad)
	Computes gradient of RHS with respect to control parameters.
void	setControlAmplitudes (const Vec x)
	Pass control parameters from global design vector to each oscillator.
double	expectedEnergy (const Vec x)
	Computes expected energy of the full composite system.
void	population (const Vec x, std::vector< double > &population_com)
	Computes population of the full composite system.

Public Attributes
std::vector< size_t >	nlevels
	Number of levels per oscillator.
std::vector< size_t >	nessential
	Number of essential levels per oscillator.
bool	usematfree
	Flag for using matrix-free solver.
DecoherenceType	decoherence_type
	Type of Lindblad operators to include (NONE means Schroedinger equation)

Protected Attributes
PetscInt	dim
	Dimension of full vectorized system: N^2 if Lindblad, N if Schroedinger.
PetscInt	dim_rho
	Dimension of Hilbert space = N.
PetscInt	dim_ess
	Dimension of essential levels = N_e.
int	noscillators
	Number of oscillators in the system.
Oscillator **	oscil_vec
	Array of pointers to oscillator objects.
Mat	RHS
	MatShell for real-valued, vectorized system matrix (size 2N^2 x 2N^2)
MatShellCtx	RHSctx
	Context containing data for applying the RHS to a state.
std::vector< Mat >	Ac_vec
std::vector< Mat >	Bc_vec
Mat	Ad
Mat	Bd
std::vector< Mat >	Ad_vec
std::vector< Mat >	Bd_vec
std::vector< double >	crosskerr
	Cross-Kerr coefficients (rad/time) \(\xi_{kl}\) for ZZ-coupling \(a_k^\dagger a_k a_l^\dagger a_l\).
std::vector< double >	Jkl
	Dipole-dipole coupling coefficients (rad/time), multiplies \(a_k^\dagger a_l + a_k a_l^\dagger\).
std::vector< double >	eta
	Frequency differences in rotating frame (rad/time) for dipole-dipole coupling.
bool	addT1
bool	addT2
	Flags for including T1 decay and T2 dephasing Lindblad operators.
int	mpirank_world
	Rank of global MPI communicator.
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.
IS	isu
IS	isv
	Vector strides for accessing real and imaginary parts u=Re(x), v=Im(x)
Vec	aux
	Auxiliary vector for computations.
bool	quietmode
	Flag for quiet mode operation.
std::optional< std::string >	hamiltonian_file_Hsys
	Filename if a custom system Hamiltonian is read from file.
std::optional< std::string >	hamiltonian_file_Hc
	Filename if a custom control Hamiltonians are read from file.

Detailed Description

Implementation of the real-valued right-hand-side (RHS) system matrix of the quantum dynamical equations.

This class provides functionality for evaluating and applying the real-valued right-hand-side (RHS) system matrix of the vectorized Lindblad master equation (open quantum systems) or Schroedinger equation (closed systems). It supports a matrix-free and a sparse-matrix version for applying the RHS to a state vector. The system matrix (RHS) is stored as a Matrix Shell, that applies the real and imaginary parts of the system matrix to the corresponding parts of the state vector separately. The RHS needs to be assembled (evaluated at each time step t) before usage.

Main functionality:

• assemble_RHS for preparing the RHS system matrix shell with current control pulse values at given time t.
• compute_dRHS_dParams for updating the gradient with += x^T*RHS(t)^T*x_bar, where x & x_bar are the primal and adjoint state at time t
• setControlAmplitudes for passing the global optimization vector to each oscillator
• expectedEnergy and population for evaluating expected energy level and level occupations of the full composite system.
• definition of MatMult interface functions to multiply the RHS matrix shell to a state vector (sparse matrix multiplication or matrix-free multiplication)

This class contains references to:

• Array of Oscillator for defining the Hamiltonian matrices for each subsystem (oscillator) and for evaluating their time-dependent control pulses at each time step

Constructor & Destructor Documentation

MasterEq() [1/2]

MasterEq::MasterEq

(

)

MasterEq() [2/2]

MasterEq::MasterEq	(	const Config &	config,
		Oscillator **	oscil_vec_,
		bool	quietmode = false
	)

Constructor with simplified configuration-based specification.

Parameters

config	Configuration parameters containing all master equation settings
oscil_vec_	Array of pointers to oscillator objects
quietmode	Flag for quiet operation (default: false)

~MasterEq()

MasterEq::~MasterEq

(

)

Member Function Documentation

assemble_RHS()

int MasterEq::assemble_RHS

(

const double

t

)

Assembles the real-valued system matrix (RHS) at time t.

Updates the time-dependent parameters in the RHS MatShell context. This must be called before applying the RHS to a state vector.

Parameters

t	Current time

Returns

int Error code

compute_dRHS_dParams()

void MasterEq::compute_dRHS_dParams	(	const double	t,
		const Vec	x,
		const Vec	x_bar,
		const double	alpha,
		Vec	grad
	)

Computes gradient of RHS with respect to control parameters.

Updates grad += alpha * x^T * (d RHS / d params)^T * x_bar. Supports both the sparse-matrix and the matrix-free version of the RHS.

Parameters

t	Current time
x	State vector
x_bar	Adjoint state vector
alpha	Scaling factor
grad	Gradient vector to update

expectedEnergy()

double MasterEq::expectedEnergy

(

const Vec

x

)

Computes expected energy of the full composite system.

Parameters

x	State vector

Returns

double Expected energy value

getDim()

PetscInt MasterEq::getDim ( )

inline

Retrieves the dimension of the vectorized system.

Returns

PetscInt \(N^2\) for Lindblad solver, \(N\) for Schroedinger solver

getDimEss()

PetscInt MasterEq::getDimEss ( )

inline

Retrieves the dimension of the essential level system.

Returns

PetscInt Dimension N_e of essential levels

getDimRho()

PetscInt MasterEq::getDimRho ( )

inline

Retrieves the dimension of the density matrix.

Returns

PetscInt Dimension N of the Hilbert space

getNOscillators()

size_t MasterEq::getNOscillators ( )

inline

Retrieves the number of oscillators in the system.

Returns

size_t Number of oscillators

getOscillator()

Oscillator * MasterEq::getOscillator ( const size_t  i )

inline

Retrieves the i-th oscillator.

Parameters

i	Index of the oscillator

Returns

Oscillator* Pointer to the oscillator object

getRHS()

Mat MasterEq::getRHS

(

)

Retrieves the right-hand-side system matrix.

Returns

Mat PETSc matrix shell object representing the RHS.

initSparseMatSolver()

void MasterEq::initSparseMatSolver

(

)

Initializes matrices needed for the sparse matrix solver.

population()

void MasterEq::population	(	const Vec	x,
		std::vector< double > &	population_com
	)

Computes population of the full composite system.

Parameters

x	State vector
population_com	Reference to vector to store population values

set_RHS_MatMult_operation()

void MasterEq::set_RHS_MatMult_operation

(

)

Pass MatMult operations for applying the RHS to PETSc.

The RHS is stored as a Matrix Shell. This routine passes the (transpose) Matrix-Multiplication operation for applying the RHS to a state vector to PETSc.

setControlAmplitudes()

void MasterEq::setControlAmplitudes

(

const Vec

x

)

Pass control parameters from global design vector to each oscillator.

Parameters

x	Global design vector containing control parameters

Member Data Documentation

Ac_vec

std::vector<Mat> MasterEq::Ac_vec

protected

Ad

Mat MasterEq::Ad

protected

Ad_vec

std::vector<Mat> MasterEq::Ad_vec

protected

addT1

bool MasterEq::addT1

protected

addT2

bool MasterEq::addT2

protected

Flags for including T1 decay and T2 dephasing Lindblad operators.

aux

Vec MasterEq::aux

protected

Auxiliary vector for computations.

Bc_vec

std::vector<Mat> MasterEq::Bc_vec

protected

Bd

Mat MasterEq::Bd

protected

Bd_vec

std::vector<Mat> MasterEq::Bd_vec

protected

crosskerr

std::vector<double> MasterEq::crosskerr

protected

Cross-Kerr coefficients (rad/time) \(\xi_{kl}\) for ZZ-coupling \(a_k^\dagger a_k a_l^\dagger a_l\).

decoherence_type

DecoherenceType MasterEq::decoherence_type

Type of Lindblad operators to include (NONE means Schroedinger equation)

dim

PetscInt MasterEq::dim

protected

Dimension of full vectorized system: N^2 if Lindblad, N if Schroedinger.

dim_ess

PetscInt MasterEq::dim_ess

protected

Dimension of essential levels = N_e.

dim_rho

PetscInt MasterEq::dim_rho

protected

Dimension of Hilbert space = N.

eta

std::vector<double> MasterEq::eta

protected

Frequency differences in rotating frame (rad/time) for dipole-dipole coupling.

hamiltonian_file_Hc

std::optional<std::string> MasterEq::hamiltonian_file_Hc

protected

Filename if a custom control Hamiltonians are read from file.

hamiltonian_file_Hsys

std::optional<std::string> MasterEq::hamiltonian_file_Hsys

protected

Filename if a custom system Hamiltonian is read from file.

ilow

PetscInt MasterEq::ilow

protected

First index of the local sub vector u,v.

isu

IS MasterEq::isu

protected

isv

IS MasterEq::isv

protected

Vector strides for accessing real and imaginary parts u=Re(x), v=Im(x)

iupp

PetscInt MasterEq::iupp

protected

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

Jkl

std::vector<double> MasterEq::Jkl

protected

Dipole-dipole coupling coefficients (rad/time), multiplies \(a_k^\dagger a_l + a_k a_l^\dagger\).

localsize_u

PetscInt MasterEq::localsize_u

protected

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

mpirank_petsc

int MasterEq::mpirank_petsc

protected

Rank of PETSc's communicator.

mpirank_world

int MasterEq::mpirank_world

protected

Rank of global MPI communicator.

mpisize_petsc

int MasterEq::mpisize_petsc

protected

Size of PETSc's communicator.

nessential

std::vector<size_t> MasterEq::nessential

Number of essential levels per oscillator.

nlevels

std::vector<size_t> MasterEq::nlevels

Number of levels per oscillator.

noscillators

int MasterEq::noscillators

protected

Number of oscillators in the system.

oscil_vec

Oscillator** MasterEq::oscil_vec

protected

Array of pointers to oscillator objects.

quietmode

bool MasterEq::quietmode

protected

Flag for quiet mode operation.

RHS

Mat MasterEq::RHS

protected

MatShell for real-valued, vectorized system matrix (size 2N^2 x 2N^2)

RHSctx

MatShellCtx MasterEq::RHSctx

protected

Context containing data for applying the RHS to a state.

usematfree

bool MasterEq::usematfree

Flag for using matrix-free solver.

---

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

• /home/runner/work/quandary/quandary/include/mastereq.hpp
• /home/runner/work/quandary/quandary/src/mastereq.cpp