Reference

class Reference(name, *extra_keys)

Bases: qiskit.pulse.instructions.instruction.Instruction

Pulse compiler directive that refers to a subroutine.

If a pulse program uses the same subset of instructions multiple times, then using the Reference class may significantly reduce the memory footprint of the program. This instruction only stores the set of strings to identify the subroutine.

The actual pulse program can be stored in the ScheduleBlock.references of the ScheduleBlock that this reference instruction belongs to.

You can later assign schedules with the ScheduleBlock.assign_references() method. This allows you to build the main program without knowing the actual subroutine, that is supplied at a later time.

Create new reference.

Parameters

• name (str) – Name of subroutine.

• extra_keys (str) – Optional. A set of string keys that may be necessary to refer to a particular subroutine. For example, when we use “sx” as a name to refer to the subroutine of an sx pulse, this name might be used among schedules for different qubits. In this example, you may specify “q0” in the extra keys to distinguish the sx schedule for qubit 0 from others. The user can use an arbitrary number of extra string keys to uniquely determine the subroutine.

Methods

append	Return a new Schedule with schedule inserted at the maximum time over all channels shared between self and schedule.
ch_duration	Return duration of the supplied channels in this Instruction.
ch_start_time	Return minimum start time for supplied channels.
ch_stop_time	Return maximum start time for supplied channels.
draw	Plot the instruction.
insert	Return a new Schedule with schedule inserted within self at start_time.
is_parameterized	Return True iff the instruction is parameterized.
shift	Return a new schedule shifted forward by time.

Attributes

channels

Returns the channels that this schedule uses.

Return type

Tuple[Channel, ...]

duration

Duration of this instruction.

Return type

Union[int, ParameterExpression]

id

Unique identifier for this instruction.

Return type

int

instructions

Iterable for getting instructions from Schedule tree.

Return type

Tuple[Tuple[int, Instruction]]

key_delimiter = ','

name

Name of this instruction.

Return type

str

operands

Return instruction operands.

Return type

Tuple

parameters

Parameters which determine the instruction behavior.

Return type

Set

ref_keys

Returns unique key of the subroutine.

Return type

Tuple[str, ...]

scope_delimiter = '::'

start_time

Relative begin time of this instruction.

Return type

int

stop_time

Relative end time of this instruction.

Return type

int