pygsti.processors.compilationrules
Defines CompilationLibrary class and supporting functions
Module Contents
Classes
A prescription for creating ("compiling") a set of gates based on another set. 

An collection of compilations for clifford gates. 
 exception pygsti.processors.compilationrules.CompilationError
Bases:
Exception
A compilation error, raised by
CompilationLibrary
Initialize self. See help(type(self)) for accurate signature.
 class pygsti.processors.compilationrules.CompilationRules(compilation_rules_dict=None)
Bases:
object
A prescription for creating (“compiling”) a set of gates based on another set.
A
CompilationRules
object contains a dictionary of gate unitaries, much like aProcessorSpec
, and instructions for creating these gates. The instructions can be given explicitly as circuits corresponding to a given gate, or implicitly as functions. Instructions can be given for gate names (e.g. “Gx”), regardless of the target state space labels of the gate, as well as for specific gate locations (e.g. (“Gx”,2)).Parameters
 compilation_rules_dictdict
A dictionary of initial rules, which can be specified in multiple formats. Keys can be either gate names as strings or gate labels as a Label object. Values are 2tuples of (gate unitary, gate template). The gate unitary can either be a unitary matrix, function returning a matrix, or None if the gate name is a standard PyGSTi unitary. The gate template is either a Circuit with local state space labels (i.e. 0..k1 for k qubits) or a function that takes the target gate label and returns the proper Circuit. If the key is a gate label, the gate template (second entry of the value tuple) MUST be a Circuit with absolute state space labels.
 classmethod cast(obj)
Convert an object into compilation rules, if it isn’t already.
Parameters
 objobject
The object to convert.
Returns
CompilationRules
 add_compilation_rule(gate_name, template_circuit_or_fn, unitary=None)
Add a compilation rule for a gate name, given as a circuit or function.
Parameters
 gate_namestr
The gate name to add a rule for.
 template_circuit_or_fnCircuit or callable
The rule. This can be specified as either a circuit or as a function. If a circuit is given, it must be on the gate’s local state space, assumed to be a kqubit space (for a kqubit gate) with qubit labels 0 to k1. That is, the circuit must have line labels equal to 0…k1. If a function if given, the function must take as a single argument a tuple of state space labels that specify the target labels of the gate.
 unitarynumpy.ndarray
The unitary corresponding to the gate. This can be left as None if gate_name names a standard or internal gate known to pyGSTi.
Returns
None
 add_specific_compilation_rule(gate_label, circuit, unitary)
Add a compilation rule for a gate at a specific location (target labels)
Parameters
 gate_labelLabel
The gate label to add a rule for. Includes the gate’s name and its target state space labels (gate_label.sslbls).
 circuitCircuit
The rule, given as a circuit on the gate’s local state space, i.e. the circuit’s line labels should be the same as gate_label.sslbls.
 unitarynumpy.ndarray
The unitary corresponding to the gate. This can be left as None if gate_label.name names a standard or internal gate known to pyGSTi.
Returns
None
 create_aux_info()
Create auxiliary information that should be stored along with the compilation rules herein.
(Currently unused, but perhaps useful in the future.)
Returns
dict
 retrieve_compilation_of(oplabel, force=False)
Get a compilation of oplabel, computing one from local templates if necessary.
Parameters
 oplabelLabel
The label of the gate to compile.
 forcebool, optional
If True, then an attempt is made to recompute a compilation even if oplabel already exists in this CompilationLibrary. Otherwise compilations are only computed when they are not present.
Returns
Circuit or None, if failed to retrieve compilation
 apply_to_processorspec(processor_spec, action='replace', gates_to_skip=None)
Use these compilation rules to convert one processor specification into another one.
Parameters
 processor_specQubitProcessorSpec
The initial processor specification, which should contain the gates present within the circuits/functions of this compilation rules object.
 action{“replace”, “add”}
Whether the existing gates in processor_spec are conveyed to the the returned processor spec. If “replace”, then they are not conveyed, if “add” they are.
 gates_to_skiplist
Gate names or labels to skip during processor specification construction.
Returns
QubitProcessorSpec
 apply_to_circuits(circuits, **kwargs)
Use these compilation rules to convert one list of circuits into another one.
Additional kwargs are passed through to Circuit.change_gate_library during translation. Common kwargs include depth_compression=False or allow_unchanged_gates=True.
Parameters
 circuitslist of Circuits
The initial circuits, which should contain the gates present within the circuits/functions of this compilation rules object.
Returns
list of Circuits
 class pygsti.processors.compilationrules.CliffordCompilationRules(native_gates_processorspec, compile_type='absolute')
Bases:
CompilationRules
An collection of compilations for clifford gates.
Holds mapping between operation labels (
Label
objects) and circuits (Circuit
objects).A CliffordCompilationRules holds a processor specification of the “native” gates of a processor and uses it to produce compilations of many of/all Clifford operations. Currently, the native gates should all be Clifford gates, so that the processor spec’s compute_clifford_symplectic_reps method gives representations for all of its gates.
Compilations can be either “local” or “nonlocal”. A local compilation ony uses gates that act on its target qubits. All 1qubit gates can be local. A nonlocal compilation uses qubits outside the set of target qubits (e.g. a CNOT between two qubits between which there is no native CNOT). Currently, nonlocal compilations can only be constructed for the CNOT gate.
To speed up the creation of local compilations, a CliffordCompilationRules instance stores “template” compilations, which specify how to construct a compilation for some kqubit gate on qubits labeled 0 to k1. When creating a compilation for a gate, a template is used if a suitable one can be found; otherwise a new template is created and then used.
Parameters
 native_gates_processorspecQubitProcessorSpec
The processor specification of “native” Clifford gates which all compilation rules are composed from.
 compile_type{“absolute”,”paulieq”}
The “compilation type” for this rules set. If “absolute”, then compilations must match the gate operation being compiled exactly. If “paulieq”, then compilations only need to match the desired gate operation up to a Paui operation (which is useful for compiling multiqubit Clifford gates / stabilizer states without unneeded 1qubit gate overheads).
 classmethod create_standard(base_processor_spec, compile_type='absolute', what_to_compile=('1Qcliffords',), verbosity=1)
Create a common set of compilation rules based on a base processor specification.
Parameters
 base_processor_specQubitProcessorSpec
The processor specification of “native” Clifford gates which all the compilation rules will be in terms of.
 compile_type{“absolute”,”paulieq”}
The “compilation type” for this rules set. If “absolute”, then compilations must match the gate operation being compiled exactly. If “paulieq”, then compilations only need to match the desired gate operation up to a Paui operation (which is useful for compiling multiqubit Clifford gates / stabilizer states without unneeded 1qubit gate overheads).
 what_to_compile{“1Qcliffords”, “localcnots”, “allcnots”, “paulis”}
What operations should rules be created for? Allowed values may depend on the value of compile_type.
Returns
CliffordCompilationRules
 add_local_compilation_of(oplabel, unitary=None, srep=None, max_iterations=10, force=False, verbosity=1)
Adds a new local compilation of oplabel.
Parameters
 oplabelLabel
The label of the gate to compile. If oplabel.name is a recognized standard Clifford name (e.g. ‘H’, ‘P’, ‘X’, ‘CNOT’) then no further information is needed. Otherwise, you must specify either (or both) of unitary or srep.
 unitarynumpy.ndarray, optional
The unitary action of the gate being compiled. If, as is typical, you’re compiling using Clifford gates, then this unitary should correspond to a Clifford operation. If you specify unitary, you don’t need to specify srep  it is computed automatically.
 sreptuple, optional
The (smatrix, svector) tuple giving the symplectic representation of the gate being compiled.
 max_iterationsint, optional
The maximum number of iterations for the iterative compilation algorithm.
 forcebool, optional
If True, then a compilation is recomputed even if oplabel already exists in this CompilationLibrary. Otherwise compilations are only computed when they are not present.
 verbosityint, optional
An integer >= 0 specifying how much detail to send to stdout.
Returns
None
 add_clifford_compilation_template(gate_name, nqubits, unitary, srep, available_gatelabels, available_sreps, verbosity=1, max_iterations=10)
Adds a new compilation template for gate_name.
Parameters
 gate_namestr
The gate name to create a compilation for. If it is recognized standard Clifford name (e.g. ‘H’, ‘P’, ‘X’, ‘CNOT’) then unitary and srep can be None. Otherwise, you must specify either (or both) of unitary or srep.
 nqubitsint
The number of qubits this gate acts upon.
 unitarynumpy.ndarray
The unitary action of the gate being templated. If, as is typical, you’re compiling using Clifford gates, then this unitary should correspond to a Clifford operation. If you specify unitary, you don’t need to specify srep  it is computed automatically.
 sreptuple, optional
The (smatrix, svector) tuple giving the symplectic representation of the gate being templated.
 available_glabelslist
A list of the gate labels (
Label
objects) that are available for use in compilations. available_srepsdict
A dictionary of available symplectic representations. Keys are gate labels and values are numpy arrays.
 verbosityint, optional
An integer >= 0 specifying how much detail to send to stdout.
 max_iterationsint, optional
The maximum number of iterations for the iterative template compilationfinding algorithm.
Returns
 tuple
A tuple of the operation labels (essentially a circuit) specifying the template compilation that was generated.
 filter_connectivity(gate_name, allowed_filter)
Compute the QubitGraph giving the available gate_name gates subject to allowed_filter.
The filter adds constraints to by specifying the availability of gate_name.
Parameters
 gate_namestr
The gate name.
 allowed_filterdict or set, optional
Specifies which gates are allowed to be to construct this connectivity. If a dict, keys must be gate names (like “CNOT”) and values
QubitGraph
objects indicating where that gate (if it’s present in the library) may be used. If a set, then it specifies a set of qubits and any gate in the current library that is confined within that set is allowed. If None, then all gates within the library are allowed.
Returns
QubitGraph
 add_nonlocal_compilation_of(oplabel, force=False, allowed_filter=None, verbosity=1, check=True)
Add a potentially nonlocal compilation of oplabel to this library.
This method currently only generates a compilation for a nonlocal CNOT, up to arbitrary Pauli gates, between a pair of unconnected qubits. It converts this CNOT into a circuit of CNOT gates between connected qubits, using a fixed circuit form. This compilation is not optimal in at least some circumstances.
If allowed_filter is None then the compilation is recorded under the key oplabel. Otherwise, the compilation is recorded under the key (oplabel,`context_key`) where context_key is frozenset(allowed_filter) when allowed_filter is a set, and context_key is frozenset(allowed_filter.items()) when allowed_filter is a dict.
Parameters
 oplabelLabel
The label of the gate to compile. Currently, oplabel.name must equal “CNOT”.
 forcebool, optional
If True, then a compilation is recomputed even if oplabel already exists in this CompilationLibrary. Otherwise compilations are only computed when they are not present.
 allowed_filterdict or set, optional
Specifies which gates are allowed to be used in this nonlocal compilation. If a dict, keys must be gate names (like “CNOT”) and values
QubitGraph
objects indicating where that gate (if it’s present in the library) may be used. If a set, then it specifies a set of qubits and any gate in the current library that is confined within that set is allowed. If None, then all gates within the library are allowed. verbosityint, optional
An integer >= 0 specifying how much detail to send to stdout.
 checkbool, optional
Whether to perform internal consistency checks.
Returns
None
 retrieve_compilation_of(oplabel, force=False, allowed_filter=None, verbosity=1, check=True)
Get a compilation of oplabel in the context of allowed_filter, if any.
This is often more convenient than querying the CompilationLibrary directly as a dictionary, because:
If allowed_filter is not None, this handles the correct querying of the dictionary to find out if there is a previously saved compilation with this allowed_filter context.
If a compilation is not present, this method will try to compute one.
This method does not store the compilation. To store the compilation first call the method add_compilation_of().
Parameters
 oplabelLabel
The label of the gate to compile.
 forcebool, optional
If True, then an attempt is made to recompute a compilation even if oplabel already exists in this CompilationLibrary. Otherwise compilations are only computed when they are not present.
 allowed_filterdict or set, optional
Specifies which gates are allowed to be used in this nonlocal compilation. If a dict, keys must be gate names (like “CNOT”) and values
QubitGraph
objects indicating where that gate (if it’s present in the library) may be used. If a set, then it specifies a set of qubits and any gate in the current library that is confined within that set is allowed. If None, then all gates within the library are allowed. verbosityint, optional
An integer >= 0 specifying how much detail to send to stdout.
 checkbool, optional
Whether to perform internal consistency checks.
Returns
Circuit
 add_compilation_of(oplabel, force=False, allowed_filter=None, verbosity=1, check=True)
Adds a compilation of oplabel in the context of allowed_filter, if any.
If allowed_filter is None then the compilation is recorded under the key oplabel. Otherwise, the compilation is recorded under the key (oplabel,`context_key`) where context_key is frozenset(allowed_filter) when allowed_filter is a set, and context_key is frozenset(allowed_filter.items()) when allowed_filter is a dict.
Parameters
 oplabelLabel
The label of the gate to compile.
 forcebool, optional
If True, then an attempt is made to recompute a compilation even if oplabel already exists in this CompilationLibrary. Otherwise compilations are only computed when they are not present.
 allowed_filterdict or set, optional
Specifies which gates are allowed to be used in this nonlocal compilation. If a dict, keys must be gate names (like “CNOT”) and values
QubitGraph
objects indicating where that gate (if it’s present in the library) may be used. If a set, then it specifies a set of qubits and any gate in the current library that is confined within that set is allowed. If None, then all gates within the library are allowed. verbosityint, optional
An integer >= 0 specifying how much detail to send to stdout.
 checkbool, optional
Whether to perform internal consistency checks.
Returns
None