pygsti.circuits.circuit

Defines the Circuit class

Module Contents

Classes

Circuit

A quantum circuit.

CompressedCircuit

A "compressed" Circuit that requires less disk space.

SeparatePOVMCircuit

Separately holds a POVM-less Circuit object, a POVM label, and a list of effect labels.

Functions

to_label(x)

Helper function for converting x to a single Label object

Attributes

msg

pygsti.circuits.circuit.msg
pygsti.circuits.circuit.to_label(x)

Helper function for converting x to a single Label object

Parameters

xvarious

An object to (attempt to) convert into a Label.

Returns

Label

class pygsti.circuits.circuit.Circuit(layer_labels=(), line_labels='auto', num_lines=None, editable=False, stringrep=None, name='', check=True, expand_subcircuits='default', occurrence=None, compilable_layer_indices=None)

Bases: object

A quantum circuit.

A Circuit represents a quantum circuit, consisting of state preparation, gates, and measurement operations. It is composed of some number of “lines”, typically one per qubit, and stores the operations on these lines as a sequence of Label objects, one per circuit layer, whose .sslbls members indicate which line(s) the label belongs on. When a circuit is created with ‘editable=True’, a rich set of operations may be used to construct the circuit in place, after which done_editing() should be called so that the Circuit can be properly hashed as needed.

Parameters

layer_labelsiterable of Labels or str

This argument provides a list of the layer labels specifying the state preparations, gates, and measurements for the circuit. This argument can also be a Circuit or a string, in which case it is parsed as a text-formatted circuit. Internally this will eventually be converted to a list of Label objects, one per layer, but it may be specified using anything that can be readily converted to a Label objects. For example, any of the following are allowed:

  • [‘Gx’,’Gx’] : X gate on each of 2 layers

  • [Label(‘Gx’),Label(‘Gx’)] : same as above

  • [(‘Gx’,0),(‘Gy’,0)] : X then Y on qubit 0 (2 layers)

  • [[(‘Gx’,0),(‘Gx’,1)],[(‘Gy’,0),(‘Gy’,1)]] : parallel X then Y on qubits 0 & 1

line_labelsiterable, optional

The (string valued) label for each circuit line. If ‘auto’, then line_labels is taken to be the list of all state-space labels present within layer_labels. If there are no such labels (e.g. if layer_labels contains just gate names like (‘Gx’,’Gy’)), then the special value ‘*’ is used as a single line label.

num_linesint, optional

Specify this instead of line_labels to set the latter to the integers between 0 and num_lines-1.

editablebool, optional

Whether the created Circuit is created in able to be modified. If True, then you should call done_editing() once the circuit is completely assembled, as this makes the circuit read-only and allows it to be hashed.

stringrepstring, optional

A string representation for the circuit. If None (the default), then this will be generated automatically when needed. One reason you’d want to specify this is if you know of a nice compact string representation that you’d rather use, e.g. “Gx^4” instead of the automatically generated “GxGxGxGx”. If you want to initialize a Circuit entirely from a string representation you can either specify the string in as layer_labels or set layer_labels to None and stringrep to any valid (one-line) circuit string.

namestr, optional

A name for this circuit (useful if/when used as a block within larger circuits).

checkbool, optional

Whether stringrep should be checked against layer_labels to ensure they are consistent, and whether the labels in layer_labels are a subset of line_labels. The only reason you’d want to set this to False is if you’re absolutely sure stringrep and line_labels are consistent and want to save computation time.

expand_subcircuitsbool or “default”

If “default”, then the value of Circuit.default_expand_subcircuits is used. If True, then any sub-circuits (e.g. anything exponentiated like “(GxGy)^4”) will be expanded when it is stored within the created Circuit. If False, then such sub-circuits will be left as-is. It’s typically more robust to expand sub-circuits as this facilitates comparison (e.g. so “GxGx” == “Gx^2”), but in cases when you have massive exponents (e.g. “Gx^8192”) it may improve performance to set expand_subcircuits=False.

occurrencehashable, optional

A value to set as the “occurrence id” for this circuit. This value doesn’t affect the circuit an any way except by affecting it’s hashing and equivalence testing. Circuits with different occurrence ids are not equivalent. Occurrence values effectively allow multiple copies of the same ciruit to be stored in a dictionary or DataSet.

compilable_layer_indicestuple, optional

The circuit-layer indices that may be internally altered (but retaining the same target operation) and/or combined with the following circuit layer by a hardware compiler.when executing this circuit. Layers that are not “compilable” are effectively followed by a barrier which prevents the hardward compiler from restructuring the circuit across the layer boundary.

Attributes

default_expand_subcircuitsbool

By default, expand sub-circuit labels.

line_labelstuple

The line labels (often qubit labels) of this circuit.

layertuptuple

This Circuit’s layers as a standard Python tuple of layer Labels.

tuptuple

This Circuit as a standard Python tuple of layer Labels and line labels.

strstr

The Python string representation of this Circuit.

Creates a new Circuit object, encapsulating a quantum circuit.

You only need to supply the first layer_labels argument, though usually (except for just 1 or 2 qubits) you’ll want to also supply line_labels or num_lines. If you’ll be adding to or altering the circuit before using it, you should set editable=True.

Parameters

layer_labelsiterable of Labels or str

This argument provides a list of the layer labels specifying the state preparations, gates, and measurements for the circuit. This argument can also be a Circuit or a string, in which case it is parsed as a text-formatted circuit. Internally this will eventually be converted to a list of Label objects, one per layer, but it may be specified using anything that can be readily converted to a Label objects. For example, any of the following are allowed:

  • [‘Gx’,’Gx’] : X gate on each of 2 layers

  • [Label(‘Gx’),Label(‘Gx’)] : same as above

  • [(‘Gx’,0),(‘Gy’,0)] : X then Y on qubit 0 (2 layers)

  • [[(‘Gx’,0),(‘Gx’,1)],[(‘Gy’,0),(‘Gy’,1)]] : parallel X then Y on qubits 0 & 1

line_labelsiterable, optional

The (string valued) label for each circuit line. If ‘auto’, then line_labels is taken to be the list of all state-space labels present within layer_labels. If there are no such labels (e.g. if layer_labels contains just gate names like (‘Gx’,’Gy’)), then the special value ‘*’ is used as a single line label.

num_linesint, optional

Specify this instead of line_labels to set the latter to the integers between 0 and num_lines-1.

editablebool, optional

Whether the created Circuit is created in able to be modified. If True, then you should call done_editing() once the circuit is completely assembled, as this makes the circuit read-only and allows it to be hashed.

stringrepstring, optional

A string representation for the circuit. If None (the default), then this will be generated automatically when needed. One reason you’d want to specify this is if you know of a nice compact string representation that you’d rather use, e.g. “Gx^4” instead of the automatically generated “GxGxGxGx”. If you want to initialize a Circuit entirely from a string representation you can either specify the string in as layer_labels or set layer_labels to None and stringrep to any valid (one-line) circuit string.

namestr, optional

A name for this circuit (useful if/when used as a block within larger circuits).

checkbool, optional

Whether stringrep should be checked against layer_labels to ensure they are consistent, and whether the labels in layer_labels are a subset of line_labels. The only reason you’d want to set this to False is if you’re absolutely sure stringrep and line_labels are consistent and want to save computation time.

expand_subcircuitsbool or “default”

If “default”, then the value of Circuit.default_expand_subcircuits is used. If True, then any sub-circuits (e.g. anything exponentiated like “(GxGy)^4”) will be expanded when it is stored within the created Circuit. If False, then such sub-circuits will be left as-is. It’s typically more robust to expand sub-circuits as this facilitates comparison (e.g. so “GxGx” == “Gx^2”), but in cases when you have massive exponents (e.g. “Gx^8192”) it may improve performance to set expand_subcircuits=False.

occurrencehashable, optional

A value to set as the “occurrence id” for this circuit. This value doesn’t affect the circuit an any way except by affecting it’s hashing and equivalence testing. Circuits with different occurrence ids are not equivalent. Occurrence values effectively allow multiple copies of the same ciruit to be stored in a dictionary or DataSet.

compilable_layer_indicestuple, optional

The circuit-layer indices that may be internally altered (but retaining the same target operation) and/or combined with the following circuit layer by a hardware compiler.when executing this circuit. Layers that are not “compilable” are effectively followed by a barrier which prevents the hardward compiler from restructuring the circuit across the layer boundary.

property line_labels

The line labels (often qubit labels) of this circuit.

property name

The name of this circuit.

Note: the name is not a part of the hashed value. The name is used to name the CircuitLabel returned from to_label().

property occurrence

The occurrence id of this circuit.

property layertup

This Circuit’s layers as a standard Python tuple of layer Labels.

Returns

tuple

property tup

This Circuit as a standard Python tuple of layer Labels and line labels.

Returns

tuple

property compilable_layer_indices

Tuple of the layer indices corresponding to “compilable” layers.

property compilable_by_layer

Boolean array indicating whether each layer is “compilable” or not.

property str

The Python string representation of this Circuit.

Returns

str

property layerstr

Just the string representation of the circuit layers (no ‘@<line_labels>’ suffix)

property linesstr

Just the string representation of the circuit’s line labels (the ‘@<line_labels>’ suffix)

property num_lines

The number of lines in this circuit.

Returns

int

property num_layers

The number of circuit layers.

In simple circuits, this is the same as the depth (given by depth()). For circuits containing sub-circuit blocks, this gives the number of top-level layers in this circuit.

Returns

int

property depth

The circuit depth.

This is the number of layers in simple circuits. For circuits containing sub-circuit blocks, this includes the full depth of these blocks. If you just want the number of top-level layers, use num_layers().

Returns

int

property width

The circuit width.

This is the number of qubits on which the circuit acts. This includes qubits that only idle, but are included as part of the circuit according to self.line_labels.

Returns

int

property size

Returns the circuit size.

This is the sum of the sizes of all the gates in the circuit. A gate that acts on n-qubits has a size of n, with the exception of the idle which has a size of 0. Hence, the circuit is given by: size = depth * num_lines - num_1Q_idles.

Returns

int

property duration
property num_gates

The number of gates in the circuit.

Returns

int

property num_multiq_gates

The number of multi-qubit (2+ qubits) gates in the circuit.

(Note that this cannot distinguish between “true” multi-qubit gates and gate that have been defined to act on more than one qubit but that represent some tensor-product gate.)

Returns

int

default_expand_subcircuits = 'True'
classmethod cast(obj)

Convert obj into a Circuit.

Parameters
objobject

Object to convert

Returns

Circuit

classmethod from_tuple(tup)

Creates a Circuit from a tuple

Parameters
tuptuple

The tuple to convert.

Returns

Circuit

to_label(nreps=1)

Construct and return this entire circuit as a CircuitLabel.

Note: occurrence-id information is not stored in a circuit label, so circuits that differ only in their occurence_id will return circuit labels that are equal.

Parameters
nrepsint, optional

The number of times this circuit will be repeated (CircuitLabels support exponentiation and you can specify this here).

Returns

CircuitLabel

repeat(ntimes, expand='default')

Repeat this circuit ntimes times.

Parameters
ntimesint

Number of repetitions.

expandbool or “default”, optional

When False, the returned circuit will contain a CircuitLabel encapsulating the repetitions without explicitly storing them. When True, the returned circuit will be expanded into the ntimes repetitions. “default” means to use the value in the class variable Circuit.default_expand_subcircuits.

copy(editable='auto')

Returns a copy of the circuit.

Parameters
editable{True,False,”auto”}

Whether returned copy is editable. If “auto” is given, then the copy is editable if and only if this Circuit is.

Returns

Circuit

clear()

Removes all the gates in a circuit (preserving the number of lines).

Returns

None

extract_labels(layers=None, lines=None, strict=True)

Get a subregion - a “rectangle” - of this Circuit.

This can be used to select multiple layers and/or lines of this Circuit. The strict argument controls whether gates need to be entirely within the given rectangle or can be intersecting it. If layers is a single integer then a Label is returned (representing a layer or a part of a layer), otherwise a Circuit is returned.

Parameters
layersint, slice, or list/tuple of ints

Which layers to select (the horizontal dimension of the selection rectangle). Layers are always selected by index, and this argument can be a single (integer) index - in which case a Label is returned - or multiple indices as given by a slice or list - in which case a Circuit is returned. Note that, even though we speak of a “rectangle”, layer indices do not need to be contiguous. The special value None selects all layers.

linesstr/int, slice, or list/tuple of strs/ints

Which lines to select (the vertical dimension of the selection rectangle). Lines are selected by their line-labels (elements of the circuit’s .line_labels property), which can be strings and/or integers. A single or multiple line-labels can be specified. If the line labels are integers a slice can be used, otherwise a list or tuple of labels is the only way to select multiple of them. Note that line-labels do not need to be contiguous. The special value None selects all lines.

strictbool, optional

When True, only gates lying completely within the selected region are included in the return value. If a gate straddles the region boundary (e.g. if we select just line 1 and the circuit contains “Gcnot:1:2”) then it is silently not-included in the returned label or circuit. If False, then gates which straddle the region boundary are included. Note that this may result in a Label or Circuit containing more line labels than where requested in the call to extract_labels(…)..

Returns
Label or Circuit

The requested portion of this circuit, given as a Label if layers is a single integer and as a Circuit otherwise. Note: if you want a Circuit when only selecting one layer, set layers to a slice or tuple containing just a single index.

set_labels(lbls, layers=None, lines=None)

Write lbls to the block defined by the layers and lines arguments.

Note that lbls can be anything interpretable as a Label or list of labels.

Parameters
lblsLabel, list/tuple of Labels, or Circuit

When layers is a single integer, lbls should be a single “layer label” of type Label. Otherwise, lbls should be a list or tuple of Label objects with length equal to the number of layers being set. A Circuit may also be used in this case.

layersint, slice, or list/tuple of ints

Which layers to set (the horizontal dimension of the destination rectangle). Layers are always selected by index, and this argument can be a single (integer) index or multiple indices as given by a slice or list. Note that these indices do not need to be contiguous. The special value None stands for all layers.

linesstr/int, slice, or list/tuple of strs/ints

Which lines to set (the vertical dimension of the destination rectangle). Lines are selected by their line-labels, which can be strings and/or integers. A single or multiple line-labels can be specified. If the line labels are integers a slice can be used, otherwise a list or tuple of labels is the only way to specify multiple of them. The line-labels do not need to be contiguous. The special value None stands for all lines, and in this case new lines will be created if there are new state-space labels in lbls (when lines is not None an error is raised instead).

Returns

None

insert_idling_layers(insert_before, num_to_insert, lines=None)

Inserts into this circuit one or more idling (blank) layers, returning a copy.

By default, complete layer(s) are inserted. The lines argument allows you to insert partial layers (on only a subset of the lines).

Parameters
insert_beforeint

The layer index to insert the new layers before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The special value None inserts at the end.

num_to_insertint

The number of new layers to insert.

linesstr/int, slice, or list/tuple of strs/ints, optional

Which lines should have new layers (blank circuit space) inserted into them. A single or multiple line-labels can be specified, similarly as in extract_labels(). The default value None stands for all lines.

Returns

Circuit

insert_idling_layers_inplace(insert_before, num_to_insert, lines=None)

Inserts into this circuit one or more idling (blank) layers.

By default, complete layer(s) are inserted. The lines argument allows you to insert partial layers (on only a subset of the lines).

Parameters
insert_beforeint

The layer index to insert the new layers before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The special value None inserts at the end.

num_to_insertint

The number of new layers to insert.

linesstr/int, slice, or list/tuple of strs/ints, optional

Which lines should have new layers (blank circuit space) inserted into them. A single or multiple line-labels can be specified, similarly as in extract_labels(). The default value None stands for all lines.

Returns

None

insert_labels_into_layers(lbls, layer_to_insert_before, lines=None)

Inserts into this circuit the contents of lbls into new full or partial layers, returning a copy.

By default, complete layer(s) are inserted. The lines argument allows you to insert partial layers (on only a subset of the lines).

Parameters
lblslist/tuple of Labels, or Circuit

The full or partial layer labels to insert. The length of this list, tuple, or circuit determines the number of layers which are inserted.

layer_to_insert_beforeint

The layer index to insert lbls before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The special value None inserts at the end.

linesstr/int, slice, or list/tuple of strs/ints, optional

Which lines should have lbls inserted into them. Currently this can only be a larger set than the set of line labels present in lbls (in future versions this may allow filtering of lbls). value None stands for all lines.

Returns

Circuit

insert_labels_into_layers_inplace(lbls, layer_to_insert_before, lines=None)

Inserts into this circuit the contents of lbls into new full or partial layers.

By default, complete layer(s) are inserted. The lines argument allows you to insert partial layers (on only a subset of the lines).

Parameters
lblslist/tuple of Labels, or Circuit

The full or partial layer labels to insert. The length of this list, tuple, or circuit determines the number of layers which are inserted.

layer_to_insert_beforeint

The layer index to insert lbls before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The special value None inserts at the end.

linesstr/int, slice, or list/tuple of strs/ints, optional

Which lines should have lbls inserted into them. Currently this can only be a larger set than the set of line labels present in lbls (in future versions this may allow filtering of lbls). value None stands for all lines.

Returns

None

insert_idling_lines(insert_before, line_labels)

Insert one or more idling (blank) lines into this circuit, returning a copy.

Parameters
insert_beforestr or int

The line label to insert new lines before. The special value None inserts lines at the bottom of this circuit.

line_labelslist or tuple

A list or tuple of the new line labels to insert (can be integers and/or strings).

Returns

Circuit

insert_idling_lines_inplace(insert_before, line_labels)

Insert one or more idling (blank) lines into this circuit.

Parameters
insert_beforestr or int

The line label to insert new lines before. The special value None inserts lines at the bottom of this circuit.

line_labelslist or tuple

A list or tuple of the new line labels to insert (can be integers and/or strings).

Returns

None

insert_labels_as_lines_inplace(lbls, layer_to_insert_before=None, line_to_insert_before=None, line_labels='auto')

Inserts into this circuit the contents of lbls into new lines.

By default, lbls is inserted at the beginning of the new lines(s). The layer_to_insert_before argument allows you to insert lbls beginning at a layer of your choice.

Parameters
lblslist/tuple of Labels, or Circuit

A list of layer labels to insert as new lines. The state-space (line) labels within lbls must not overlap with that of this circuit or an error is raised. If lbls contains more layers than this circuit currently has, new layers are added automatically.

layer_to_insert_beforeint

The layer index to insert lbls before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The default value of None inserts at the beginning.

line_to_insert_beforestr or int

The line label to insert the new lines before. The default value of None inserts lines at the bottom of the circuit.

line_labelslist, tuple, or “auto”

The labels of the new lines being inserted. If “auto”, then these are inferred from lbls.

Returns

None

insert_labels_as_lines(lbls, layer_to_insert_before=None, line_to_insert_before=None, line_labels='auto')

Inserts into this circuit the contents of lbls into new lines, returning a copy.

By default, lbls is inserted at the beginning of the new lines(s). The layer_to_insert_before argument allows you to insert lbls beginning at a layer of your choice.

Parameters
lblslist/tuple of Labels, or Circuit

A list of layer labels to insert as new lines. The state-space (line) labels within lbls must not overlap with that of this circuit or an error is raised. If lbls contains more layers than this circuit currently has, new layers are added automatically.

layer_to_insert_beforeint

The layer index to insert lbls before. Can be from 0 (insert at the beginning) to len(self)-1 (insert at end), and negative indexing can be used to insert relative to the last layer. The default value of None inserts at the beginning.

line_to_insert_beforestr or int

The line label to insert the new lines before. The default value of None inserts lines at the bottom of the circuit.

line_labelslist, tuple, or “auto”

The labels of the new lines being inserted. If “auto”, then these are inferred from lbls.

Returns

None

clear_labels(layers=None, lines=None, clear_straddlers=False)

Removes all the gates within the given circuit region. Does not reduce the number of layers or lines.

Parameters
layersint, slice, or list/tuple of ints

Defines the horizontal dimension of the region to clear. See extract_labels() for details.

linesstr/int, slice, or list/tuple of strs/ints

Defines the vertical dimension of the region to clear. See extract_labels() for details.

clear_straddlersbool, optional

Whether or not gates which straddle cleared and non-cleared lines should be cleared. If False and straddling gates exist, an error will be raised.

Returns

None

delete_layers(layers=None)

Deletes one or more layers from the circuit.

Parameters
layersint, slice, or list/tuple of ints

The layer index or indices to delete. See extract_labels() for details.

Returns

None

delete_lines(lines, delete_straddlers=False)

Deletes one or more lines from the circuit.

Parameters
linesstr/int, slice, or list/tuple of strs/ints

The line label(s) to delete. See extract_labels() for details.

delete_straddlersbool, optional

Whether or not gates which straddle deleted and non-deleted lines should be removed. If False and straddling gates exist, an error will be raised.

Returns

None

to_pythonstr(op_labels)

Convert this circuit to an “encoded” python string.

In the returned string each operation label is represented as a single character, starting with ‘A’ and continuing down the alphabet. This can be useful for processing operation sequences using python’s string tools (regex in particular).

Parameters
op_labelstuple

An iterable containing at least all the layer-Labels that appear in this Circuit, and which will be mapped to alphabet characters, beginning with ‘A’.

Returns
string

The converted operation sequence.

Examples

(‘Gx’,’Gx’,’Gy’,’Gx’) => “AABA”

classmethod from_pythonstr(python_string, op_labels)

Decode an “encoded string” into a Circuit.

Create a Circuit from a python string where each operation label is represented as a single character, starting with ‘A’ and continuing down the alphabet. This performs the inverse of to_pythonstr().

Parameters
python_stringstring

string whose individual characters correspond to the operation labels of a operation sequence.

op_labelstuple

tuple containing all the operation labels that will be mapped from alphabet characters, beginning with ‘A’.

Returns

Circuit

Examples

“AABA” => (‘Gx’,’Gx’,’Gy’,’Gx’)

serialize(expand_subcircuits=False)

Serialize the parallel gate operations of this Circuit.

Construct a new Circuit whereby all layers containing multiple gates are converted to separate single-gate layers, effectively putting each elementary gate operation into its own layer. Ordering is dictated by the ordering of the compound layer labels.

Parameters
expand_subcircuitsbool

Whether subcircuits should be expanded before performing the serialization. If False, the circuit may contain CircuitLabel layers.

Returns

Circuit

parallelize(can_break_labels=True, adjacent_only=False)

Compress a circuit’s gates by performing them in parallel.

Construct a circuit with the same underlying labels as this one, but with as many gates performed in parallel as possible (with some restrictions - see the Parameters section below). Generally, gates are moved as far left (toward the start) of the circuit as possible.

Parameters
can_break_labelsbool, optional

Whether compound (parallel-gate) labels in this Circuit can be separated during the parallelization process. For example, if can_break_labels=True then “Gx:0[Gy:0Gy:1]” => “[Gx:0Gy:1]Gy:0” whereas if can_break_labels=False the result would remain “Gx:0[Gy:0Gy:1]” because [Gy:0Gy:1] cannot be separated.

adjacent_onlybool, optional

It True, then operation labels are only allowed to move into an adjacent label, that is, they cannot move “through” other operation labels. For example, if adjacent_only=True then “Gx:0Gy:0Gy:1” => “Gx:0[Gy:0Gy:1]” whereas if adjacent_only=False the result would be “[Gx:0Gy:1]Gy:0. Setting this to True is sometimes useful if you want to parallelize a serial string in such a way that subsequently calling .serialize() will give you back the original string.

Returns

Circuit

expand_subcircuits_inplace()

Expands all CircuitLabel labels within this circuit.

This operation is done in place and so can only be performed on an editable Circuit.

Returns

None

expand_subcircuits()

Returns a new circuit with CircuitLabel labels expanded.

Returns

Circuit

factorize_repetitions_inplace()

Attempt to replace repeated sub-circuits with CircuitLabel objects.

More or less the reverse of expand_subcircuits(), this method attempts to collapse repetitions of the same labels into single CircuitLabel labels within this circuit.

This operation is done in place and so can only be performed on an editable Circuit.

Returns

None

insert_layer(circuit_layer, j)

Inserts a single layer into a circuit, returning a copy.

The input layer does not need to contain a gate that acts on every qubit, but it should not contain more than one gate on a qubit.

Parameters
circuit_layerLabel

The layer to insert. A (possibly compound) Label object or something that can be converted into one, e.g. ((‘Gx’,0),(‘Gcnot’,1,2)) or just ‘Gx’.

jint

The layer index (depth) at which to insert the circuit_layer.

Returns

Circuit

insert_layer_inplace(circuit_layer, j)

Inserts a single layer into a circuit.

The input layer does not need to contain a gate that acts on every qubit, but it should not contain more than one gate on a qubit.

Parameters
circuit_layerLabel

The layer to insert. A (possibly compound) Label object or something that can be converted into one, e.g. ((‘Gx’,0),(‘Gcnot’,1,2)) or just ‘Gx’.

jint

The layer index (depth) at which to insert the circuit_layer.

Returns

None

insert_circuit(circuit, j)

Inserts a circuit into this circuit, returning a copy.

The circuit to insert can be over more qubits than this circuit, as long as all qubits that are not part of this circuit are idling. In this case, the idling qubits are all discarded. The circuit to insert can also be on less qubits than this circuit: all other qubits are set to idling. So, the labels of the circuit to insert for all non-idling qubits must be a subset of the labels of this circuit.

Parameters
circuitCircuit

The circuit to be inserted.

jint

The layer index (depth) at which to insert the circuit.

Returns

Circuit

insert_circuit_inplace(circuit, j)

Inserts a circuit into this circuit.

The circuit to insert can be over more qubits than this circuit, as long as all qubits that are not part of this circuit are idling. In this case, the idling qubits are all discarded. The circuit to insert can also be on less qubits than this circuit: all other qubits are set to idling. So, the labels of the circuit to insert for all non-idling qubits must be a subset of the labels of this circuit.

Parameters
circuitCircuit

The circuit to be inserted.

jint

The layer index (depth) at which to insert the circuit.

Returns

None

append_circuit(circuit)

Append a circuit to the end of this circuit, returning a copy.

This circuit must satisfy the requirements of insert_circuit(). See that method for more details.

Parameters
circuitA Circuit object

The circuit to be appended.

Returns

Circuit

append_circuit_inplace(circuit)

Append a circuit to the end of this circuit.

This circuit must satisfy the requirements of insert_circuit(). See that method for more details.

Parameters
circuitA Circuit object

The circuit to be appended.

Returns

None

prefix_circuit(circuit)

Prefix a circuit to the beginning of this circuit, returning a copy.

This circuit must satisfy the requirements of the insert_circuit(). See that method for more details.

Parameters
circuitA Circuit object

The circuit to be prefixed.

Returns

Circuit

prefix_circuit_inplace(circuit)

Prefix a circuit to the beginning of this circuit.

This circuit must satisfy the requirements of the insert_circuit(). See that method for more details.

Parameters
circuitA Circuit object

The circuit to be prefixed.

Returns

None

tensor_circuit_inplace(circuit, line_order=None)

The tensor product of this circuit and circuit.

That is, it adds circuit to this circuit as new lines. The line labels of circuit must be disjoint from the line labels of this circuit, as otherwise applying the circuits in parallel does not make sense.

Parameters
circuitA Circuit object

The circuit to be tensored.

line_orderList, optional

A list of all the line labels specifying the order of the circuit in the updated circuit. If None, the lines of circuit are added below the lines of this circuit. Note that, for many purposes, the ordering of lines of the circuit is irrelevant.

Returns

None

tensor_circuit(circuit, line_order=None)

The tensor product of this circuit and circuit, returning a copy.

That is, it adds circuit to this circuit as new lines. The line labels of circuit must be disjoint from the line labels of this circuit, as otherwise applying the circuits in parallel does not make sense.

Parameters
circuitA Circuit object

The circuit to be tensored.

line_orderList, optional

A list of all the line labels specifying the order of the circuit in the updated circuit. If None, the lines of circuit are added below the lines of this circuit. Note that, for many purposes, the ordering of lines of the circuit is irrelevant.

Returns

Circuit

replace_layer_with_circuit_inplace(circuit, j)

Replaces the j-th layer of this circuit with circuit.

Parameters
circuitCircuit

The circuit to insert

jint

The layer index to replace.

Returns

None

replace_layer_with_circuit(circuit, j)

Replaces the j-th layer of this circuit with circuit, returning a copy.

Parameters
circuitCircuit

The circuit to insert

jint

The layer index to replace.

Returns

Circuit

replace_gatename_inplace(old_gatename, new_gatename)

Changes the name of a gate throughout this Circuit.

Note that the name is only a part of the label identifying each gate, and doesn’t include the lines (qubits) a gate acts upon. For example, the “Gx:0” and “Gx:1” labels both have the same name but act on different qubits.

Parameters
old_gatenamestr

The gate name to replace.

new_gatenamestr

The name to replace old_gatename with.

Returns

None

replace_gatename(old_gatename, new_gatename)

Returns a copy of this Circuit except that old_gatename is changed to new_gatename.

Note that the “name” is only a part of the “label” identifying each gate, and doesn’t include the lines (qubits) a gate acts upon. For example, the “Gx:0” and “Gx:1” labels both have the same name but act on different qubits.

Parameters
old_gatenamestr

The gate name to replace.

new_gatenamestr

The name to replace old_gatename with.

Returns

Circuit

replace_gatename_with_idle_inplace(gatename)

Treats a given gatename as an idle gate throughout this Circuit.

This effectively removes this gate name from the circuit, and replaces a layer containing only this gate name with an idle layer.

Parameters
gatenamestr

The gate name to replace.

Returns

None

replace_gatename_with_idle(gatename)

Returns a copy of this Circuit with a given gatename treated as an idle gate.

This effectively removes this gate name from the circuit, and replaces a layer containing only this gate name with an idle layer.

Parameters
gatenamestr

The gate name to replace.

Returns

Circuit

replace_layer(old_layer, new_layer)

Returns a copy of this Circuit except that old_layer is changed to new_layer.

Parameters
old_layerstr or Label

The layer to find.

new_layerstr or Label

The layer to replace found layers with.

Returns

Circuit

replace_layers_with_aliases(alias_dict)

Performs a find and replace using layer aliases.

Returns a copy of this Circuit except that it’s layers that match keys of alias_dict are replaced with the corresponding values.

Parameters
alias_dictdict

A dictionary whose keys are layer Labels (or equivalent tuples or strings), and whose values are Circuits.

Returns

Circuit

change_gate_library(compilation, allowed_filter=None, allow_unchanged_gates=False, depth_compression=True, one_q_gate_relations=None)

Re-express a circuit over a different model.

Parameters
compilationdict or CompilationLibrary.

If a dictionary, the keys are some or all of the gates that appear in the circuit, and the values are replacement circuits that are normally compilations for each of these gates (if they are not, the action of the circuit will be changed). The circuits need not be on all of the qubits, and need only satisfy the requirements of the insert_circuit method. There must be a key for every gate except the self.identity gate, unless allow_unchanged_gates is False. In that case, gate that aren’t a key in this dictionary are left unchanged.

If a CompilationLibrary, this will be queried via the retrieve_compilation_of() method to find compilations for all of the gates in the circuit. So this CompilationLibrary must contain or be able to auto-generate compilations for the requested gates, except when allow_unchanged_gates is True. In that case, gates that a compilation is not returned for are left unchanged.

allowed_filterdict or set, optional

Specifies which gates are allowed to be used when generating compilations from compilation. Can only be not None if compilation is a CompilationLibrary. If a dict, keys must be gate names (like “Gcnot”) 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.

allow_unchanged_gatesbool, optional

Whether to allow some gates to remain unchanged, and therefore to be absent from compilation. When True such gates are left alone; when False an error is raised if any such gates are encountered.

depth_compressionbool, optional

Whether to perform depth compression after changing the gate library. If one_q_gate_relations is None this will only remove idle layers and compress the circuit by moving everything as far forward as is possible without knowledge of the action of any gates other than self.identity. See the depth_compression method for more details. Under most circumstances this should be true; if it is False changing gate library will often result in a massive increase in circuit depth.

one_q_gate_relationsdict, optional

Gate relations for the one-qubit gates in the new gate library, that are used in the depth compression, to cancel / combine gates. E.g., one key-value pair might be (‘Gh’,’Gh’) : ‘I’, to signify that two Hadamards c ompose to the idle gate ‘Gi’. See the depth_compression() method for more details.

Returns

None

map_names_inplace(mapper)

The names of all of the simple labels are updated in-place according to the mapping function mapper.

Parameters
mapperdict or function

A dictionary whose keys are the existing gate name values and whose values are the new names (strings) or a function which takes a single (existing name) argument and returns a new name.

Returns

None

map_state_space_labels_inplace(mapper)

The labels of all of the lines (wires/qubits) are updated according to the mapping function mapper.

Parameters
mapperdict or function

A dictionary whose keys are the existing self.line_labels values and whose value are the new labels, or a function which takes a single (existing line-label) argument and returns a new line-label.

Returns

None

map_state_space_labels(mapper)

Creates a new Circuit whose line labels are updated according to the mapping function mapper.

Parameters
mapperdict or function

A dictionary whose keys are the existing self.line_labels values and whose value are the new labels, or a function which takes a single (existing line-label) argument and returns a new line-label.

Returns

Circuit

reorder_lines_inplace(order)

Reorders the lines (wires/qubits) of the circuit.

Note that the ordering of the lines is unimportant for most purposes.

Parameters
orderlist

A list containing all of the circuit line labels (self.line_labels) in the order that the should be converted to.

Returns

None

reorder_lines(order)

Reorders the lines (wires/qubits) of the circuit, returning a copy.

Note that the ordering of the lines is unimportant for most purposes.

Parameters
orderlist

A list containing all of the circuit line labels (self.line_labels) in the order that the should be converted to.

Returns

Circuit

idling_lines(idle_layer_labels=None)

Returns the line labels corresponding to idling lines.

Parameters
idle_layer_labelsiterable, optional

A list or tuple of layer-labels that should be treated as idle operations, so their presence will not disqualify a line from being “idle”. E.g. [“Gi”] will cause “Gi” layers to be considered idle layers.

Returns

tuple

delete_idling_lines_inplace(idle_layer_labels=None)

Removes from this circuit all lines that are idling at every layer.

Parameters
idle_layer_labelsiterable, optional

A list or tuple of layer-labels that should be treated as idle operations, so their presence will not disqualify a line from being “idle”. E.g. [“Gi”] will cause “Gi” layers to be considered idle layers.

Returns

None

delete_idling_lines(idle_layer_labels=None)

Removes from this circuit all lines that are idling at every layer, returning a copy.

Parameters
idle_layer_labelsiterable, optional

A list or tuple of layer-labels that should be treated as idle operations, so their presence will not disqualify a line from being “idle”. E.g. [“Gi”] will cause “Gi” layers to be considered idle layers.

Returns

Circuit

replace_with_idling_line_inplace(line_label, clear_straddlers=True)

Converts the specified line to an idling line, by removing all its gates.

If there are any multi-qubit gates acting on this line, this function will raise an error when clear_straddlers=False.

Parameters
line_labelstr or int

The label of the line to convert to an idling line.

clear_straddlersbool, optional

Whether or not gates which straddle the line_label should also be cleared. If False and straddling gates exist, an error will be raised.

Returns

None

reverse_inplace()

Reverses the order of the circuit.

Returns

None

delete_idle_layers_inplace()

Deletes all layers in this circuit that contain no gate operations.

One of the steps of the depth_compression() method.

Returns
bool

False if the circuit is unchanged, and True otherwise.

compress_depth_inplace(one_q_gate_relations=None, verbosity=0)

Compresses the depth of this circuit using very simple re-write rules.

  1. If one_q_gate_relations is provided, all sequences of 1-qubit gates in the circuit are compressed as far as is possible using only the pair-wise combination rules provided by this dict (see below).

  2. All gates are shifted forwarded as far as is possible without any knowledge of what any of the gates are.

  3. All idle-only layers are deleted.

Parameters
one_q_gate_relationsdict

Keys that are pairs of strings, corresponding to 1-qubit gate names, with values that are a single string, also corresponding to a 1-qubit gate name. Whenever a 1-qubit gate with name name1 is followed in the circuit by a 1-qubit gate with name2 then, if one_q_gate_relations[name1,name2] = name3, name1 -> name3 and name2 -> self.identity, the identity name in the circuit. Moreover, this is still implemented when there are self.identity gates between these 1-qubit gates, and it is implemented iteratively in the sense that if there is a sequence of 1-qubit gates with names name1, name2, name3, … and there are relations for all of (name1,name2) -> name12, (name12,name3) -> name123 etc then the entire sequence of 1-qubit gates will be compressed into a single possibly non-idle 1-qubit gate followed by idle gates in place of the previous 1-qubit gates.

If a QubitProcessorSpec object has been created for the gates/device in question, the QubitProcessorSpec.oneQgate_relations is the appropriate (and auto-generated) one_q_gate_relations.

Note that this function will not compress sequences of 1-qubit gates that cannot be compressed by independently inspecting sequential non-idle pairs (as would be the case with, for example, Gxpi Gzpi Gxpi Gzpi, if the relation did not know that (Gxpi,Gzpi) -> Gypi, even though the sequence is the identity).

verbosityint, optional

If > 0, information about the depth compression is printed to screen.

Returns

None

layer(j)

Returns a tuple of the components, i.e. the (non-identity) gates, in the layer at depth j.

These are the .components of the Label returned by indexing this Circuit (using square brackets) with j, i.e. this returns this_circuit[j].components.

Parameters
jint

The index (depth) of the layer to be returned

Returns

tuple

layer_label(j)

Returns the layer, as a Label, at depth j.

This label contains as components all the (non-identity) gates in the layer..

Parameters
jint

The index (depth) of the layer to be returned

Returns

Label

layer_with_idles(j, idle_gate_name='I')

Returns a tuple of the components of the layer at depth j, with idle_gate_name at empty circuit locations.

This effectively places an explicit idle_gate_name gates wherever there is an implied identity operation in the circuit.

Parameters
jint

The index (depth) of the layer to be returned

idle_gate_namestr, optional

The idle gate name to use. Note that state space (qubit) labels will be added to this name to form a Label.

Returns

tuple

layer_label_with_idles(j, idle_gate_name='I')

Returns the layer, as a Label, at depth j, with idle_gate_name at empty circuit locations.

This effectively places an explicit idle_gate_name gates wherever there is an implied identity operation in the circuit.

Parameters
jint

The index (depth) of the layer to be returned

idle_gate_namestr, optional

The idle gate name to use. Note that state space (qubit) labels will be added to this name to form a Label.

Returns

Label

two_q_gate_count()

The number of two-qubit gates in the circuit.

(Note that this cannot distinguish between “true” 2-qubit gates and gate that have been defined to act on two qubits but that represent some tensor-product gate.)

Returns

int

num_nq_gates(nq)

The number of nq-qubit gates in the circuit.

(Note that this cannot distinguish between “true” nq-qubit gates and gate that have been defined to act on nq qubits but that represent some tensor-product gate.)

Parameters
nqint

The qubit-count of the gates to count. For example, if nq == 3, this function returns the number of 3-qubit gates.

Returns

int

format_display_str(width=80)

Formats a string for displaying this circuit suject to a maximum width.

Parameters
widthint, optional

The maximum width in characters. If the circuit is longer than this width it is wrapped using multiple lines (like a musical score).

Returns

str

convert_to_cirq(qubit_conversion, wait_duration=None, gatename_conversion=None, idle_gate_name='Gi')

Converts this circuit to a Cirq circuit.

Parameters
qubit_conversiondict

Mapping from qubit labels (e.g. integers) to Cirq qubit objects.

wait_durationcirq.Duration, optional

If no gatename_conversion dict is given, the idle operation is not converted to a gate. If wait_diration is specified and gatename_conversion is not specified, then the idle operation will be converted to a cirq.WaitGate with the specified duration.

gatename_conversiondict, optional

If not None, a dictionary that converts the gatenames in the circuit to the Cirq gates that will appear in the Cirq circuit. If only standard pyGSTi names are used (e.g., ‘Gh’, ‘Gp’, ‘Gcnot’, ‘Gcphase’, etc) this dictionary need not be specified, and an automatic conversion to the standard Cirq names will be implemented.

idle_gate_namestr, optional

Name to use for idle gates. Defaults to ‘Gi’

Returns

A Cirq Circuit object.

classmethod from_cirq(circuit, qubit_conversion=None, cirq_gate_conversion=None, remove_implied_idles=True, global_idle_replacement_label='auto')

Converts and instantiates a pyGSTi Circuit object from a Cirq Circuit object.

Parameters
circuitcirq Circuit

The cirq Circuit object to parse into a pyGSTi circuit.

qubit_conversiondict, optional (default None)

A dictionary specifying a mapping between cirq qubit objects and pyGSTi qubit labels (either integers or strings). If None, then a default mapping is created.

cirq_gate_conversiondict, optional (default None)

If specified a dictionary with keys given by cirq gate objects, and values given by pygsti gate names which overrides the built-in conversion dictionary used by default.

remove_implied_idlesbool, optional (default True)

A flag indicating whether to remove explicit idles that are part of a circuit layer containing other explicitly specified gates (i.e., whether to abide by the normal pyGSTi implicit idle convention).

global_idle_replacement_labelstring or Label or None, optional (default ‘auto’)

An option specified for the handling of global idle layers. If None, no replacement of global idle layers is performed and a verbatim conversion from the cirq layer is performed. If the string ‘auto’, then the behavior is to replace global idle layers with the gate label Label(()), which is the special syntax for the global idle layer, stylized typically as ‘[]’. If another string then replace with a gate label with the specified name acting on all of the qubits appearing in the cirq circuit. If a Label object, use this directly, this does not check for compatibility so it is up to the user to ensure the labels are compatible.

Returns
pygsti_circuit

A pyGSTi Circuit instance equivalent to the specified Cirq one.

convert_to_quil(num_qubits=None, gatename_conversion=None, qubit_conversion=None, readout_conversion=None, block_between_layers=True, block_idles=True, gate_declarations=None)

Converts this circuit to a quil string.

Parameters
num_qubitsint, optional

The number of qubits for the quil file. If None, then this is assumed to equal the number of line labels in this circuit.

gatename_conversiondict, optional

A dictionary mapping gate names contained in this circuit to the corresponding gate names used in the rendered quil. If None, a standard set of conversions is used (see standard_gatenames_quil_conversions()).

qubit_conversiondict, optional

If not None, a dictionary converting the qubit labels in the circuit to the desired qubit labels in the quil output. Can be left as None if the qubit labels are either (1) integers, or (2) of the form ‘Qi’ for integer i. In this case they are converted to integers (i.e., for (1) the mapping is trivial, for (2) the mapping strips the ‘Q’).

readout_conversiondict, optional

If not None, a dictionary converting the qubit labels mapped through qubit_conversion to the bit labels for readot. E.g. Suppose only qubit 2 (on Rigetti hardware) is in use. Then the pyGSTi string will have only one qubit (labeled 0); it will get remapped to 2 via qubit_conversion={0:2}. At the end of the quil circuit, readout should go recorded in bit 0, so readout_conversion = {0:0}. (That is, qubit with pyGSTi label 0 gets read to Rigetti bit 0, even though that qubit has Rigetti label 2.)

block_between_layersbool, optional

When True, add in a barrier after every circuit layer. Including such “pragma” blocks can be important for QCVV testing, as this can help reduce the “behind-the-scenes” compilation (beyond necessary conversion to native instructions) experience by the circuit.

block_idlesbool, optional

In the special case of global idle gates, pragma-block barriers are inserted even when block_between_layers=False. Set block_idles=False to disable this behavior, whcih typically results in global idle gates being removed by the compiler.

gate_declarationsdict, optional

If not None, a dictionary that provides unitary maps for particular gates that are not already in the quil syntax.

Returns
str

A quil string.

convert_to_openqasm(num_qubits=None, standard_gates_version='u3', gatename_conversion=None, qubit_conversion=None, block_between_layers=True, block_between_gates=False, include_delay_on_idle=True, gateargs_map=None)

Converts this circuit to an openqasm string.

Parameters
num_qubitsint, optional

The number of qubits for the openqasm file. If None, then this is assumed to equal the number of line labels in this circuit.

versionstring, optional

Either ‘u3’ or ‘x-sx-rz’. Specifies the naming convention for the QASM gates. With ‘u3’, all single-qubit gates are specified in terms of the ‘u3’ gate, used by IBM and QisKit until ~2021 (see the qasm_u3 function). With ‘x-sx-rz’, all single-gates are specified in terms of ‘x’ (an x pi rotation), ‘sx’ (an x pi/2 rotation) and ‘rz’ (a parameterized rotation around z by an angle theta).

gatename_conversiondict, optional

If not None, a dictionary that converts the gatenames in the circuit to the gatenames that will appear in the openqasm output. If only standard pyGSTi names are used (e.g., ‘Gh’, ‘Gp’, ‘Gcnot’, ‘Gcphase’, etc) this dictionary need not be specified, and an automatic conversion to the standard openqasm names will be implemented.

qubit_conversiondict, optional

If not None, a dictionary converting the qubit labels in the circuit to the desired qubit labels in the openqasm output. Can be left as None if the qubit labels are either (1) integers, or (2) of the form ‘Qi’ for integer i. In this case they are converted to integers (i.e., for (1) the mapping is trivial, for (2) the mapping strips the ‘Q’).

block_between_layersbool, optional

When True, add in a barrier after every circuit layer. Including such barriers can be important for QCVV testing, as this can help reduce the “behind-the-scenes” compilation (beyond necessary conversion to native instructions) experience by the circuit.

block_between_gates: bool, optional

When True, add in a barrier after every gate (effectively serializing the circuit). Defaults to False.

include_delay_on_idle: bool, optional

When True, includes a delay operation on implicit idles in each layer, as per Qiskit’s OpenQASM 2.0 convention after the deprecation of the id operation. Defaults to True, which is commensurate with legacy usage of this function. However, this can now be set to False to avoid this behaviour if generating actually valid OpenQASM (with no opaque delay instruction) is desired.

gateargs_mapdict, optional

If not None, a dict that maps strings (representing pyGSTi standard gate names) to functions that map the parameters of a pyGSTi gate to a string to be combined with the QASM name to specify the specific gate, in QASM. If only standard pyGSTi names are used (e.g., ‘Gh’, ‘Gzr’, ‘Gczr, etc) or none of the gates are parameterized, this dictionary need not be specified, and an automatic conversion to the standard openqasm format will be implemented.

Returns
str

An openqasm string.

simulate(model, return_all_outcomes=False)

Compute the outcome probabilities of this Circuit using model as a model for the gates.

The order of the outcome strings (e.g., ‘0100’) is w.r.t. to the ordering of the qubits in the circuit. That is, the ith element of the outcome string corresponds to the qubit with label self.line_labels[i].

Parameters
modelModel

A description of the gate and SPAM operations corresponding to the labels stored in this Circuit. If this model is over more qubits than the circuit, the output will be the probabilities for the qubits in the circuit marginalized, if possible over the other qubits. But, the simulation is over the full set of qubits in the model, and so the time taken for the simulation scales with the number of qubits in the model. For models where “spectator” qubits do not affect the qubits in this circuit (such as with perfect gates), more efficient simulations will be obtained by first creating a model only over the qubits in this circuit.

return_all_outcomesbool, optional

Whether to include outcomes in the returned dictionary that have zero probability. When False, the threshold for discarding an outcome as z ero probability is 10^-12.

Returns
probsdictionary

A dictionary with keys equal to all (return_all_outcomes is True) or possibly only some (return_all_outcomes is False) of the possible outcomes, and values that are float probabilities.

done_editing()

Make this circuit read-only, so that it can be hashed (e.g. used as a dictionary key).

This is done automatically when attempting to hash a Circuit for the first time, so there’s calling this function can usually be skipped (but it’s good for code clarity).

Returns

None

expand_instruments_and_separate_povm(model, observed_outcomes=None)

Creates a dictionary of SeparatePOVMCircuit objects from expanding the instruments of this circuit.

Each key of the returned dictionary replaces the instruments in this circuit with a selection of their members. (The size of the resulting dictionary is the product of the sizes of each instrument appearing in this circuit when observed_outcomes is None). Keys are stored as SeparatePOVMCircuit objects so it’s easy to keep track of which POVM outcomes (effects) correspond to observed data. This function is, for the most part, used internally to process a circuit before computing its outcome probabilities.

Parameters
modelModel

The model used to provide necessary details regarding the expansion, including:

  • default SPAM layers

  • definitions of instrument-containing layers

  • expansions of individual instruments and POVMs

Returns
OrderedDict

A dict whose keys are SeparatePOVMCircuit objects and whose values are tuples of the outcome labels corresponding to this circuit, one per POVM effect held in the key.

class pygsti.circuits.circuit.CompressedCircuit(circuit, min_len_to_compress=20, max_period_to_look_for=20)

Bases: object

A “compressed” Circuit that requires less disk space.

The tuple of circuit layers is compressed using a custom algorithm which looks for repeated portions of the circuit.

One place where CompressedCircuit objects can be useful is when saving large lists of long operation sequences in some non-human-readable format (e.g. pickle). CompressedCircuit objects cannot be used in place of Circuit objects within pyGSTi, and so are not useful when manipulating and running algorithms which use operation sequences.

Parameters

circuitCircuit

The operation sequence object which is compressed to create a new CompressedCircuit object.

min_len_to_compressint, optional

The minimum length string to compress. If len(circuit) is less than this amount its tuple is returned.

max_period_to_look_forint, optional

The maximum period length to use when searching for periodic structure within circuit. Larger values mean the method takes more time but could result in better compressing.

Create a new CompressedCircuit object

Parameters

circuitCircuit

The operation sequence object which is compressed to create a new CompressedCircuit object.

min_len_to_compressint, optional

The minimum length string to compress. If len(circuit) is less than this amount its tuple is returned.

max_period_to_look_forint, optional

The maximum period length to use when searching for periodic structure within circuit. Larger values mean the method takes more time but could result in better compressing.

expand()

Expands this compressed operation sequence into a Circuit object.

Returns

Circuit

static compress_op_label_tuple(circuit, min_len_to_compress=20, max_period_to_look_for=20)

Compress a operation sequence.

The result is tuple with a special compressed- gate-string form form that is not useable by other GST methods but is typically shorter (especially for long operation sequences with a repetative structure) than the original operation sequence tuple.

Parameters
circuittuple of operation labels or Circuit

The operation sequence to compress.

min_len_to_compressint, optional

The minimum length string to compress. If len(circuit) is less than this amount its tuple is returned.

max_period_to_look_forint, optional

The maximum period length to use when searching for periodic structure within circuit. Larger values mean the method takes more time but could result in better compressing.

Returns
tuple

The compressed (or raw) operation sequence tuple.

static expand_op_label_tuple(compressed_op_labels)

Expand a compressed tuple (created with compress_op_label_tuple()) into a tuple of operation labels.

Parameters
compressed_op_labelstuple

a tuple in the compressed form created by compress_op_label_tuple(…).

Returns
tuple

A tuple of operation labels specifying the uncompressed operation sequence.

class pygsti.circuits.circuit.SeparatePOVMCircuit(circuit_without_povm, povm_label, effect_labels)

Bases: object

Separately holds a POVM-less Circuit object, a POVM label, and a list of effect labels.

This is often used to hold “expanded” circuits whose instrument labels have been replaced with specific instrument members and whose POVMs have simillarly been “expanded” except that we keep the entire expanded POVM together in this one data structure. (There’s no especially good reason for this other than practicality - that since almost all circuits end with a POVM, holding each POVM outcome (effect) separately would be very wasteful.

property full_effect_labels