qnet.algebra package¶
Symbolic quantum and photonic circuit (SLH) algebra
Subpackages:
Summary¶
__all__
Exceptions:
AlgebraError 
Base class for all algebraic errors 
AlgebraException 
Base class for all algebraic exceptions 
BadLiouvillianError 
Raised when a Liouvillian is not of standard Lindblad form. 
BasisNotSetError 
Raised if the basis or a Hilbert space dimension is unavailable 
CannotConvertToSLH 
Raised when a circuit algebra object cannot be converted to SLH 
CannotEliminateAutomatically 
Raised when attempted automatic adiabatic elimination fails. 
CannotSimplify 
Raised when a rule cannot further simplify an expression 
CannotSymbolicallyDiagonalize 
Matrix cannot be diagonalized analytically. 
CannotVisualize 
Raised when a circuit cannot be visually represented. 
IncompatibleBlockStructures 
Raised for invalid blockdecomposition 
InfiniteSumError 
Raised when expanding a sum into an infinite number of terms 
NoConjugateMatrix 
Raised when entries of Matrix have no defined conjugate 
NonSquareMatrix 
Raised when a Matrix fails to be square 
OverlappingSpaces 
Raised when objects fail to be in separate Hilbert spaces. 
SpaceTooLargeError 
Raised when objects fail to be have overlapping Hilbert spaces. 
UnequalSpaces 
Raised when objects fail to be in the same Hilbert space. 
WrongCDimError 
Raised for mismatched channel number in circuit series 
__all__
Classes:
Adjoint 
Symbolic Adjoint of an operator 
BasisKet 
Local basis state, identified by index or label 
Beamsplitter 
Infinite bandwidth beamsplitter component. 
Bra 
The associated dual/adjoint state for any ket 
BraKet 
The symbolic inner product between two states 
CPermutation 
Channel permuting circuit 
Circuit 
Base class for the circuit algebra elements 
CircuitSymbol 
Symbolic circuit element 
CoherentDriveCC 
Coherent displacement of the input field 
CoherentStateKet 
Local coherent state, labeled by a complex amplitude 
Commutator 
Commutator of two operators 
Component 
Base class for circuit components 
Concatenation 
Concatenation of circuit elements 
Create 
Bosonic creation operator 
Destroy 
Bosonic annihilation operator 
Displace 
Unitary coherent displacement operator 
Eq 
Symbolic equation 
Expression 
Base class for all QNET Expressions 
Feedback 
Feedback on a single channel of a circuit 
HilbertSpace 
Base class for Hilbert spaces 
IndexedSum 
Base class for indexed sums 
Jminus 
Lowering operator on a spin space 
Jplus 
Raising operator of a spin space 
Jz 
Spin (angular momentum) operator in zdirection 
KetBra 
Outer product of two states 
KetIndexedSum 
Indexed sum over Kets 
KetPlus 
Sum of states 
KetSymbol 
Symbolic state 
LocalKet 
A state on a LocalSpace 
LocalOperator 
Base class for “known” operators on a LocalSpace 
LocalSigma 
Level flip operator between two levels of a LocalSpace 
LocalSpace 
Hilbert space for a single degree of freedom. 
MatchDict 
Result of a Pattern.match() 
Matrix 
Matrix of Expressions 
NullSpaceProjector 
Projection operator onto the nullspace of its operand 
Operation 
Base class for “operations” 
Operator 
Base class for all quantum operators. 
OperatorDerivative 
Symbolic partial derivative of an operator 
OperatorIndexedSum 
Indexed sum over operators 
OperatorPlus 
Sum of Operators 
OperatorPlusMinusCC 
An operator plus or minus its complex conjugate 
OperatorSymbol 
Symbolic operator 
OperatorTimes 
Product of operators 
OperatorTimesKet 
Product of an operator and a state. 
OperatorTrace 
(Partial) trace of an operator 
Pattern 
Pattern for matching an expression 
Phase 
Unitary “phase” operator 
PhaseCC 
Coherent phase shift cicuit component 
ProductSpace 
Tensor product of local Hilbert spaces 
PseudoInverse 
Symbolic pseudoinverse \(X^+\) of an operator \(X\) 
QuantumAdjoint 
Base class for adjoints of quantum expressions 
QuantumDerivative 
Symbolic partial derivative 
QuantumExpression 
Base class for expressions associated with a Hilbert space 
QuantumIndexedSum 
Base class for indexed sums 
QuantumOperation 
Base class for operations on quantum expression 
QuantumPlus 
General implementation of addition of quantum expressions 
QuantumSymbol 
Symbolic element of an algebra 
QuantumTimes 
General implementation of product of quantum expressions 
SLH 
Element of the SLH algebra 
SPost 
Linear postmultiplication operator 
SPre 
Linear premultiplication operator 
Scalar 
Base class for Scalars 
ScalarDerivative 
Symbolic partial derivative of a scalar 
ScalarExpression 
Base class for scalars with nonscalar arguments 
ScalarIndexedSum 
Indexed sum over scalars 
ScalarPlus 
Sum of scalars 
ScalarPower 
A scalar raised to a power 
ScalarTimes 
Product of scalars 
ScalarTimesKet 
Product of a Scalar coefficient and a ket 
ScalarTimesOperator 
Product of a Scalar coefficient and an Operator 
ScalarTimesQuantumExpression 
Product of a Scalar and a QuantumExpression 
ScalarTimesSuperOperator 
Product of a Scalar coefficient and a SuperOperator 
ScalarValue 
Wrapper around a numeric or symbolic value 
SeriesInverse 
Symbolic series product inversion operation 
SeriesProduct 
The series product circuit operation. 
SingleQuantumOperation 
Base class for operations on a single quantum expression 
SpinOperator 
Base class for operators in a spin space 
SpinSpace 
A Hilbert space for an integer or halfinteger spin system 
Squeeze 
Unitary squeezing operator 
State 
Base class for states in a Hilbert space 
StateDerivative 
Symbolic partial derivative of a state 
SuperAdjoint 
Adjoint of a superoperator 
SuperOperator 
Base class for superoperators 
SuperOperatorDerivative 
Symbolic partial derivative of a superoperator 
SuperOperatorPlus 
A sum of superoperators 
SuperOperatorSymbol 
Symbolic superoperator 
SuperOperatorTimes 
Product of superoperators 
SuperOperatorTimesOperator 
Application of a superoperator to an operator 
TensorKet 
A tensor product of kets 
__all__
Functions:
FB 
Wrapper for Feedback , defaulting to last channel 
KroneckerDelta 
Kronecker delta symbol 
LocalProjector 
A projector onto a specific level of a LocalSpace 
PauliX 
Paulitype Xoperator 
PauliY 
Paulitype Yoperator 
PauliZ 
Paulitype Zoperator 
SpinBasisKet 
Constructor for a BasisKet for a SpinSpace 
Sum 
Instantiator for an arbitrary indexed sum. 
adjoint 
Return the adjoint of an obj. 
anti_commutator 
If B != None , return the anticommutator \(\{A,B\}\), otherwise return the superoperator \(\{A,\cdot\}\). 
block_matrix 
Generate the operator matrix with quadrants 
circuit_identity 
Return the circuit identity for n channels 
commutator 
Commutator of A and B 
connect 
Connect a list of components according to a list of connections. 
decompose_space 
Simplifies OperatorTrace expressions over tensorproduct spaces by turning it into iterated partial traces. 
diagm 
Generalizes the diagonal matrix creation capabilities of numpy.diag to Matrix objects. 
eval_adiabatic_limit 
Compute the limiting SLH model for the adiabatic approximation 
expand_commutators_leibniz 
Recursively expand commutators in expr according to the Leibniz rule. 
extract_channel 
Create a CPermutation that extracts channel k 
factor_coeff 
Factor out coefficients of all factors. 
factor_for_trace 
Given a LocalSpace ls to take the partial trace over and an operator op, factor the trace such that operators acting on disjoint degrees of freedom are pulled out of the trace.If the operator acts trivially on ls the trace yields only a prefactor equal to the dimension of ls.If there are LocalSigma operators among a product, the trace’s cyclical property is used to move to sandwich the full product by LocalSigma operators:. 
getABCD 
Calculate the ABCDlinearization of an SLH model 
get_coeffs 
Create a dictionary with all Operator terms of the expression (understood as a sum) as keys and their coefficients as values. 
hstackm 
Generalizes numpy.hstack to Matrix objects. 
identity_matrix 
Generate the Ndimensional identity matrix. 
init_algebra 
Initialize the algebra system 
lindblad 
Return the superoperator Lindblad term of the Lindblad operator C 
liouvillian 
Return the Liouvillian superoperator associated with H and Ls 
liouvillian_normal_form 
Return a Hamilton operator H and a minimal list of collapse operators Ls that generate the liouvillian L . 
map_channels 
Create a CPermuation based on a dict of channel mappings 
match_pattern 
Recursively match expr with the given expr_or_pattern 
move_drive_to_H 
Move coherent drives from the Lindblad operators to the Hamiltonian 
no_instance_caching 
Temporarily disable instance caching in create() 
pad_with_identity 
Pad a circuit by adding a nchannel identity circuit at index k 
pattern 
‘Flat’ constructor for the Pattern class 
pattern_head 
Constructor for a Pattern matching a ProtoExpr 
prepare_adiabatic_limit 
Prepare the adiabatic elimination on an SLH object 
rewrite_with_operator_pm_cc 
Try to rewrite expr using OperatorPlusMinusCC 
sqrt 
Square root of a Scalar or scalar value 
substitute 
Substitute symbols or (sub)expressions with the given replacements and reevalute the result 
symbols 
The symbols() function from SymPy 
temporary_instance_cache 
Use a temporary cache for instances in create() 
temporary_rules 
Allow temporary modification of rules for create() 
try_adiabatic_elimination 
Attempt to automatically do adiabatic elimination on an SLH object 
vstackm 
Generalizes numpy.vstack to Matrix objects. 
wc 
Constructor for a wildcardPattern 
zerosm 
Generalizes numpy.zeros to Matrix objects. 
__all__
Data:
CIdentity 
Single passthrough channel; neutral element of SeriesProduct 
CircuitZero 
Zero circuit, the neutral element of Concatenation 
FullSpace 
The ‘full space’, i.e. 
II 
IdentityOperator constant (singleton) object. 
IdentityOperator 
IdentityOperator constant (singleton) object. 
IdentitySuperOperator 
Neutral element for product of superoperators 
One 
The neutral element with respect to scalar multiplication 
TrivialKet 
TrivialKet constant (singleton) object. 
TrivialSpace 
The ‘nullspace’, i.e. 
Zero 
The neutral element with respect to scalar addition 
ZeroKet 
ZeroKet constant (singleton) object for the nullstate. 
ZeroOperator 
ZeroOperator constant (singleton) object. 
ZeroSuperOperator 
Neutral element for sum of superoperators 
tr 
Instantiate while applying automatic simplifications 
Reference¶

qnet.algebra.
init_algebra
(*, default_hs_cls='LocalSpace')[source]¶ Initialize the algebra system
Parameters: default_hs_cls (str) – The name of the LocalSpace
subclass that should be used when implicitly creating Hilbert spaces, e.g. inOperatorSymbol