pygsti.processors.compilationrules

Defines CompilationLibrary class and supporting functions

Module Contents

Classes

CompilationRules	A prescription for creating ("compiling") a set of gates based on another set.
CliffordCompilationRules	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 a ProcessorSpec, 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 2-tuples 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..k-1 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 k-qubit space (for a k-qubit gate) with qubit labels 0 to k-1. That is, the circuit must have line labels equal to 0…k-1. 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 “non-local”. A local compilation ony uses gates that act on its target qubits. All 1-qubit gates can be local. A non-local compilation uses qubits outside the set of target qubits (e.g. a CNOT between two qubits between which there is no native CNOT). Currently, non-local 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 k-qubit gate on qubits labeled 0 to k-1. 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 multi-qubit Clifford gates / stabilizer states without unneeded 1-qubit gate over-heads).

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 multi-qubit Clifford gates / stabilizer states without unneeded 1-qubit gate over-heads).

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 compilation-finding 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 non-local compilation of oplabel to this library.

This method currently only generates a compilation for a non-local 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 non-local 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:

1. 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.

2. 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 non-local 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 non-local 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