ScheduleBlock
class qiskit.pulse.ScheduleBlock(name=None, metadata=None, alignment_context=None)
Bases: object
Time-ordered sequence of instructions with alignment context.
ScheduleBlock
supports lazy scheduling of context instructions, i.e. their timeslots is always generated at runtime. This indicates we can parametrize instruction durations as well as other parameters. In contrast to Schedule
being somewhat static, ScheduleBlock
is a dynamic representation of a pulse program.
Pulse Builder
The Qiskit pulse builder is a domain specific language that is developed on top of the schedule block. Use of the builder syntax will improve the workflow of pulse programming. See Pulse Builder for a user guide.
Alignment contexts
A schedule block is always relatively scheduled. Instead of taking individual instructions with absolute execution time t0
, the schedule block defines a context of scheduling and instructions under the same context are scheduled in the same manner (alignment). Several contexts are available in Alignments. A schedule block is instantiated with one of these alignment contexts. The default context is AlignLeft
, for which all instructions are left-justified, in other words, meaning they use as-soon-as-possible scheduling.
If you need an absolute-time interval in between instructions, you can explicitly insert Delay
instructions.
Nested blocks
A schedule block can contain other nested blocks with different alignment contexts. This enables advanced scheduling, where a subset of instructions is locally scheduled in a different manner. Note that a Schedule
instance cannot be directly added to a schedule block. To add a Schedule
instance, wrap it in a Call
instruction. This is implicitly performed when a schedule is added through the Pulse Builder.
Unsupported operations
Because the schedule block representation lacks timeslots, it cannot perform particular Schedule
operations such as insert()
or shift()
that require instruction start time t0
. In addition, exclude()
and filter()
methods are not supported because these operations may identify the target instruction with t0
. Except for these operations, ScheduleBlock
provides full compatibility with Schedule
.
Subroutine
The timeslots-free representation offers much greater flexibility for writing pulse programs. Because ScheduleBlock
only cares about the ordering of the child blocks we can add an undefined pulse sequence as a subroutine of the main program. If your program contains the same sequence multiple times, this representation may reduce the memory footprint required by the program construction. Such a subroutine is realized by the special compiler directive Reference
that is defined by a unique set of reference key strings to the subroutine. The (executable) subroutine is separately stored in the main program. Appended reference directives are resolved when the main program is executed. Subroutines must be assigned through assign_references()
before execution.
One way to reference a subroutine in a schedule is to use the pulse builder’s reference()
function to declare an unassigned reference. In this example, the program is called with the reference key “grand_child”. You can call a subroutine without specifying a substantial program.
from qiskit import pulse
from qiskit.circuit.parameter import Parameter
amp1 = Parameter("amp1")
amp2 = Parameter("amp2")
with pulse.build() as sched_inner:
pulse.play(pulse.Constant(100, amp1), pulse.DriveChannel(0))
with pulse.build() as sched_outer:
with pulse.align_right():
pulse.reference("grand_child")
pulse.play(pulse.Constant(200, amp2), pulse.DriveChannel(0))
# Now assign the inner pulse program to this reference
sched_outer.assign_references({("grand_child",): sched_inner})
print(sched_outer.parameters)
{Parameter(amp1), Parameter(amp2)}
The outer program now has the parameter amp2
from the inner program, indicating that the inner program’s data has been made available to the outer program. The program calling the “grand_child” has a reference program description which is accessed through ScheduleBlock.references
.
print(sched_outer.references)
ReferenceManager:
- ('grand_child',): ScheduleBlock(Play(Constant(duration=100, amp=amp1,...
Finally, you may want to call this program from another program. Here we try a different approach to define subroutine. Namely, we call a subroutine from the root program with the actual program sched2
.
amp3 = Parameter("amp3")
with pulse.build() as main:
pulse.play(pulse.Constant(300, amp3), pulse.DriveChannel(0))
pulse.call(sched_outer, name="child")
print(main.parameters)
{Parameter(amp1), Parameter(amp2), Parameter(amp3}
This implicitly creates a reference named “child” within the root program and assigns sched_outer
to it.
Note that the root program is only aware of its direct references.
print(main.references)
ReferenceManager:
- ('child',): ScheduleBlock(ScheduleBlock(ScheduleBlock(Play(Con...
As you can see the main program cannot directly assign a subroutine to the “grand_child” because this subroutine is not called within the root program, i.e. it is indirectly called by “child”. However, the returned ReferenceManager
is a dict-like object, and you can still reach to “grand_child” via the “child” program with the following chained dict access.
main.references[("child", )].references[("grand_child", )]
Note that ScheduleBlock.parameters
still collects all parameters also from the subroutine once it’s assigned.
Create an empty schedule block.
The class qiskit.pulse.schedule.ScheduleBlock
is deprecated as of Qiskit 1.3. It will be removed in Qiskit 2.0. The entire Qiskit Pulse package is being deprecated and will be moved to the Qiskit Dynamics repository: https://github.com/qiskit-community/qiskit-dynamics
Parameters
- name (str | None) – Name of this schedule. Defaults to an autogenerated string if not provided.
- metadata (dict | None) – Arbitrary key value metadata to associate with the schedule. This gets stored as free-form data in a dict in the
metadata
attribute. It will not be directly used in the schedule. - alignment_context (AlignmentKind) –
AlignmentKind
instance that manages scheduling of instructions in this block.
Raises
TypeError – if metadata is not a dict.
Attributes
alignment_context
Return alignment instance that allocates block component to generate schedule.
blocks
Get the block elements added to self.
The sequence of elements is returned in order of addition. Because the first element is schedule first, e.g. FIFO, the returned sequence is roughly time-ordered. However, in the parallel alignment context, especially in the as-late-as-possible scheduling, or AlignRight
context, the actual timing of when the instructions are issued is unknown until the ScheduleBlock
is scheduled and converted into a Schedule
.
channels
Returns channels that this schedule block uses.
duration
Duration of this schedule block.
instances_counter
Default value: count(0)
instructions
Get the time-ordered instructions from self.
metadata
The user provided metadata associated with the schedule.
User provided dict
of metadata for the schedule. The metadata contents do not affect the semantics of the program but are used to influence the execution of the schedule. It is expected to be passed between all transforms of the schedule and that providers will associate any schedule metadata with the results it returns from the execution of that schedule.
name
Return name of this schedule
parameters
Return unassigned parameters with raw names.
prefix
Default value: 'block'
references
Return a reference manager of the current scope.
Methods
append
append(block, name=None, inplace=True)
Return a new schedule block with block
appended to the context block. The execution time is automatically assigned when the block is converted into schedule.
Parameters
- block (BlockComponent) – ScheduleBlock to be appended.
- name (str | None) – Name of the new
Schedule
. Defaults to name ofself
. - inplace (bool) – Perform operation inplace on this schedule. Otherwise, return a new
Schedule
.
Returns
Schedule block with appended schedule.
Raises
PulseError – When invalid schedule type is specified.
Return type
assign_parameters
assign_parameters(value_dict, inplace=True)
Assign the parameters in this schedule according to the input.
Parameters
- value_dict (dict[ParameterExpression |ParameterVector |str, ParameterValueType | Sequence[ParameterValueType]]) – A mapping from parameters or parameter names (parameter vector
- values (or parameter vector name) to either numeric) –
- expression (or another parameter) –
- inplace (bool) – Set
True
to override this instance with new parameter.
Returns
Schedule with updated parameters.
Raises
PulseError – When the block is nested into another block.
Return type
assign_references
assign_references(subroutine_dict, inplace=True)
Assign schedules to references.
It is only capable of assigning a schedule block to immediate references which are directly referred within the current scope. Let’s see following example:
from qiskit import pulse
with pulse.build() as nested_prog:
pulse.delay(10, pulse.DriveChannel(0))
with pulse.build() as sub_prog:
pulse.reference("A")
with pulse.build() as main_prog:
pulse.reference("B")
In above example, the main_prog
can refer to the subroutine “root::B” and the reference of “B” to program “A”, i.e., “B::A”, is not defined in the root namespace. This prevents breaking the reference “root::B::A” by the assignment of “root::B”. For example, if a user could indirectly assign “root::B::A” from the root program, one can later assign another program to “root::B” that doesn’t contain “A” within it. In this situation, a reference “root::B::A” would still live in the reference manager of the root. However, the subroutine “root::B::A” would no longer be used in the actual pulse program. To assign subroutine “A” to nested_prog
as a nested subprogram of main_prog
, you must first assign “A” of the sub_prog
, and then assign the sub_prog
to the main_prog
.
sub_prog.assign_references({("A", ): nested_prog}, inplace=True)
main_prog.assign_references({("B", ): sub_prog}, inplace=True)
Alternatively, you can also write
main_prog.assign_references({("B", ): sub_prog}, inplace=True)
main_prog.references[("B", )].assign_references({("A", ): nested_prog}, inplace=True)
Here references
returns a dict-like object, and you can mutably update the nested reference of the particular subroutine.
Assigned programs are deep-copied to prevent an unexpected update.
Parameters
- subroutine_dict (dict[str |tuple[str, ...], 'ScheduleBlock']) – A mapping from reference key to schedule block of the subroutine.
- inplace (bool) – Set
True
to override this instance with new subroutine.
Returns
Schedule block with assigned subroutine.
Raises
PulseError – When reference key is not defined in the current scope.
Return type
ch_duration
ch_duration(*channels)
Return the time of the end of the last instruction over the supplied channels.
Parameters
*channels (Channel) – Channels within self
to include.
Return type
draw
draw(style=None, backend=None, time_range=None, time_unit='dt', disable_channels=None, show_snapshot=True, show_framechange=True, show_waveform_info=True, plot_barrier=True, plotter='mpl2d', axis=None, show_barrier=True)
Plot the schedule.
Parameters
-
style (dict[str, Any] | None) – Stylesheet options. This can be dictionary or preset stylesheet classes. See
IQXStandard
,IQXSimple
, andIQXDebugging
for details of preset stylesheets. -
backend (Optional[BaseBackend]) – Backend object to play the input pulse program. If provided, the plotter may use to make the visualization hardware aware.
-
time_range (tuple[int, int] | None) – Set horizontal axis limit. Tuple
(tmin, tmax)
. -
time_unit (str) – The unit of specified time range either
dt
orns
. The unit of ns is available only whenbackend
object is provided. -
disable_channels (list[Channel] | None) – A control property to show specific pulse channel. Pulse channel instances provided as a list are not shown in the output image.
-
show_snapshot (bool) – Show snapshot instructions.
-
show_framechange (bool) – Show frame change instructions. The frame change represents instructions that modulate phase or frequency of pulse channels.
-
show_waveform_info (bool) – Show additional information about waveforms such as their name.
-
plot_barrier (bool) – Show barrier lines.
-
plotter (str) –
Name of plotter API to generate an output image. One of following APIs should be specified:
mpl2d: Matplotlib API for 2D image generation. Matplotlib API to generate 2D image. Charts are placed along y axis with vertical offset. This API takes matplotlib.axes.Axes as ``axis`` input.
axis
andstyle
kwargs may depend on the plotter. -
axis (Any | None) – Arbitrary object passed to the plotter. If this object is provided, the plotters use a given
axis
instead of internally initializing a figure object. This object format depends on the plotter. See plotter argument for details. -
show_barrier (bool) – DEPRECATED. Show barrier lines.
Returns
Visualization output data. The returned data type depends on the plotter
. If matplotlib family is specified, this will be a matplotlib.pyplot.Figure
data.
exclude
exclude(*filter_funcs, channels=None, instruction_types=None, check_subroutine=True)
Return a new ScheduleBlock
with only the instructions from this ScheduleBlock
failing at least one of the provided filters. This method is the complement of filter()
, so that:
self.filter(args) + self.exclude(args) == self in terms of instructions included.
Because ScheduleBlock
is not aware of the execution time of the context instructions, excluding some instructions may change the execution time of the remaining instructions.
Parameters
- filter_funcs (Callable[..., bool]) – A list of Callables which take a
Instruction
and return a bool. - channels (Iterable[Channel] | None) – For example,
[DriveChannel(0), AcquireChannel(0)]
. - instruction_types (Iterable[abc.ABCMeta] | abc.ABCMeta) – For example,
[PulseInstruction, AcquireInstruction]
. - check_subroutine (bool) – Set True to individually filter instructions inside of a subroutine defined by the
Call
instruction.
Returns
ScheduleBlock
consisting of instructions that do not match with at least one of filtering conditions.
filter
filter(*filter_funcs, channels=None, instruction_types=None, check_subroutine=True)
Return a new ScheduleBlock
with only the instructions from this ScheduleBlock
which pass though the provided filters; i.e. an instruction will be retained if every function in filter_funcs
returns True
, the instruction occurs on a channel type contained in channels
, and the instruction type is contained in instruction_types
.
Because ScheduleBlock
is not aware of the execution time of the context instructions, filtering out some instructions may change the execution time of the remaining instructions.
If no arguments are provided, self
is returned.
Parameters
- filter_funcs (Callable[..., bool]) – A list of Callables which take a
Instruction
and return a bool. - channels (Iterable[Channel] | None) – For example,
[DriveChannel(0), AcquireChannel(0)]
. - instruction_types (Iterable[abc.ABCMeta] | abc.ABCMeta) – For example,
[PulseInstruction, AcquireInstruction]
. - check_subroutine (bool) – Set True to individually filter instructions inside a subroutine defined by the
Call
instruction.
Returns
ScheduleBlock
consisting of instructions that matches with filtering condition.
get_parameters
get_parameters(parameter_name)
Get parameter object bound to this schedule by string name.
Note that we can define different parameter objects with the same name, because these different objects are identified by their unique uuid. For example,
from qiskit import pulse, circuit
amp1 = circuit.Parameter("amp")
amp2 = circuit.Parameter("amp")
with pulse.build() as sub_prog:
pulse.play(pulse.Constant(100, amp1), pulse.DriveChannel(0))
with pulse.build() as main_prog:
pulse.call(sub_prog, name="sub")
pulse.play(pulse.Constant(100, amp2), pulse.DriveChannel(0))
main_prog.get_parameters("amp")
This returns a list of two parameters amp1
and amp2
.
Parameters
parameter_name (str) – Name of parameter.
Returns
Parameter objects that have corresponding name.
Return type
initialize_from
classmethod initialize_from(other_program, name=None)
Create new schedule object with metadata of another schedule object.
Parameters
- other_program (Any) – Qiskit program that provides metadata to new object.
- name (str | None) – Name of new schedule. Name of
block
is used by default.
Returns
New block object with name and metadata.
Raises
PulseError – When other_program
does not provide necessary information.
Return type
is_parameterized
is_referenced
is_referenced()
Return True iff the current schedule block contains reference to subroutine.
Return type
is_schedulable
replace
replace(old, new, inplace=True)
Return a ScheduleBlock
with the old
component replaced with a new
component.
Parameters
- old (ScheduleBlock |Instruction) – Schedule block component to replace.
- new (ScheduleBlock |Instruction) – Schedule block component to replace with.
- inplace (bool) – Replace instruction by mutably modifying this
ScheduleBlock
.
Returns
The modified schedule block with old
replaced by new
.
Return type