QPY serialization (qiskit.qpy
)¶
QPY is a binary serialization format for QuantumCircuit
and
ScheduleBlock
objects that is designed to be cross-platform,
Python version agnostic, and backwards compatible moving forward. QPY should
be used if you need a mechanism to save or copy between systems a
QuantumCircuit
or ScheduleBlock
that preserves the full
Qiskit object structure (except for custom attributes defined outside of
Qiskit code). This differs from other serialization formats like
OpenQASM (2.0 or 3.0) which has a
different abstraction model and can result in a loss of information contained
in the original circuit (or is unable to represent some aspects of the
Qiskit objects) or Python’s pickle
which will preserve the Qiskit object exactly but will only work for a single Qiskit
version (it is also
potentially insecure).
Using QPY¶
Using QPY is defined to be straightforward and mirror the user API of the
serializers in Python’s standard library, pickle
and json
. There are
2 user facing functions: qiskit.qpy.dump()
and
qiskit.qpy.load()
which are used to dump QPY data
to a file object and load circuits from QPY data in a file object respectively.
For example:
from qiskit.circuit import QuantumCircuit
from qiskit import qpy
qc = QuantumCircuit(2, name='Bell', metadata={'test': True})
qc.h(0)
qc.cx(0, 1)
qc.measure_all()
with open('bell.qpy', 'wb') as fd:
qpy.dump(qc, fd)
with open('bell.qpy', 'rb') as fd:
new_qc = qpy.load(fd)[0]
The qiskit.qpy.dump()
function also lets you
include multiple circuits in a single QPY file:
with open('twenty_bells.qpy', 'wb') as fd:
qpy.dump([qc] * 20, fd)
and then loading that file will return a list with all the circuits
- with open(“twenty_bells.qpy”, “rb”) as fd:
twenty_new_bells = qpy.load(fd)
API documentation¶
|
Load a QPY binary file |
|
Write QPY binary data to a file |
QPY Compatibility¶
The QPY format is designed to be backwards compatible moving forward. This means you should be able to load a QPY with any newer Qiskit version than the one that generated it. However, loading a QPY file with an older Qiskit version is not supported and may not work.
For example, if you generated a QPY file using qiskit-terra 0.18.1 you could load that QPY file with qiskit-terra 0.19.0 and a hypothetical qiskit-terra 0.29.0. However, loading that QPY file with 0.18.0 is not supported and may not work.
QPY Format¶
The QPY serialization format is a portable cross-platform binary
serialization format for QuantumCircuit
objects in Qiskit. The basic
file format is as follows:
A QPY file (or memory object) always starts with the following 7
byte UTF8 string: QISKIT
which is immediately followed by the overall
file header. The contents of the file header as defined as a C struct are:
struct {
uint8_t qpy_version;
uint8_t qiskit_major_version;
uint8_t qiskit_minor_version;
uint8_t qiskit_patch_version;
uint64_t num_circuits;
}
All values use network byte order 1 (big endian) for cross platform compatibility.
The file header is immediately followed by the circuit payloads. Each individual circuit is composed of the following parts:
HEADER | METADATA | REGISTERS | CUSTOM_DEFINITIONS | INSTRUCTIONS
There is a circuit payload for each circuit (where the total number is dictated
by num_circuits
in the file header). There is no padding between the
circuits in the data.
Version 7¶
Version 7 adds support for Reference
instruction and serialization of
a ScheduleBlock
program while keeping its reference to subroutines:
from qiskit import pulse
from qiskit import qpy
with pulse.build() as schedule:
pulse.reference("cr45p", "q0", "q1")
pulse.reference("x", "q0")
pulse.reference("cr45p", "q0", "q1")
with open('template_ecr.qpy', 'wb') as fd:
qpy.dump(schedule, fd)
The conventional SCHEDULE_BLOCK data model is preserved, but in version 7 it is immediately followed by an extra MAPPING utf8 bytes block representing the data of the referenced subroutines.
New type key character is added to the SCHEDULE_BLOCK_INSTRUCTIONS group
for the Reference
instruction.
y
:Reference
instruction
New type key character is added to the SCHEDULE_BLOCK_OPERANDS group
for the operands of Reference
instruction,
which is a tuple of strings, e.g. («cr45p», «q0», «q1»).
o
: string (operand string)
Note that this is the same encoding with the built-in Python string, however,
the standard value encoding in QPY uses s
type character for string data,
which conflicts with the SymbolicPulse
in the scope of
pulse instruction operands. A special type character o
is reserved for
the string data that appears in the pulse instruction operands.
In addition, version 7 adds two new type keys to the INSTRUCTION_PARM struct. "d"
is followed
by no data and represents the literal value CASE_DEFAULT
for switch-statement support.
"R"
represents a ClassicalRegister
or Clbit
, and is followed by the same
format as the description of register or classical bit as used in the first element of the
condition of an INSTRUCTION field.
Version 6¶
Version 6 adds support for ScalableSymbolicPulse
. These objects are saved and read
like SymbolicPulse objects, and the class name is added to the data to correctly handle
the class selection.
SymbolicPulse block now starts with SYMBOLIC_PULSE_V2 header:
struct {
uint16_t class_name_size;
uint16_t type_size;
uint16_t envelope_size;
uint16_t constraints_size;
uint16_t valid_amp_conditions_size;
_bool amp_limited;
}
The only change compared to Version 5 is the addition of class_name_size. The header
is then immediately followed by class_name_size
utf8 bytes with the name of the class. Currently,
either SymbolicPulse or ScalableSymbolicPulse are supported. The rest of the data is then
identical to Version 5.
Version 5¶
Version 5 changes from Version 4 by adding support for ScheduleBlock
and changing two payloads the INSTRUCTION metadata payload and the CUSTOM_INSTRUCTION block.
These now have new fields to better account for ControlledGate
objects in a circuit.
In addition, new payload MAP_ITEM is defined to implement the MAPPING block.
With the support of ScheduleBlock
, now QuantumCircuit
can be
serialized together with calibrations
, or
Pulse Gates.
In QPY version 5 and above, CIRCUIT_CALIBRATIONS payload is
packed after the INSTRUCTIONS block.
In QPY version 5 and above,
struct {
char type;
}
immediately follows the file header block to represent the program type stored in the file.
When
type==c
,QuantumCircuit
payload followsWhen
type==s
,ScheduleBlock
payload follows
Nota
Different programs cannot be packed together in the same file. You must create different files for different program types. Multiple objects with the same type can be saved in a single file.
SCHEDULE_BLOCK¶
ScheduleBlock
is first supported in QPY Version 5. This allows
users to save pulse programs in the QPY binary format as follows:
from qiskit import pulse, qpy
with pulse.build() as schedule:
pulse.play(pulse.Gaussian(160, 0.1, 40), pulse.DriveChannel(0))
with open('schedule.qpy', 'wb') as fd:
qpy.dump(qc, fd)
with open('schedule.qpy', 'rb') as fd:
new_qc = qpy.load(fd)[0]
Note that circuit and schedule block are serialized and deserialized through the same QPY interface. Input data type is implicitly analyzed and no extra option is required to save the schedule block.
SCHEDULE_BLOCK_HEADER¶
ScheduleBlock
block starts with the following header:
struct {
uint16_t name_size;
uint64_t metadata_size;
uint16_t num_element;
}
which is immediately followed by name_size
utf8 bytes of schedule name and
metadata_size
utf8 bytes of the JSON serialized metadata dictionary
attached to the schedule.
SCHEDULE_BLOCK_ALIGNMENTS¶
Then, alignment context of the schedule block starts with char
representing the supported context type followed by the SEQUENCE block representing
the parameters associated with the alignment context AlignmentKind._context_params
.
The context type char is mapped to each alignment subclass as follows:
l
:AlignLeft
r
:AlignRight
Note that AlignFunc
context is not supported becasue of the callback function
stored in the context parameters.
SCHEDULE_BLOCK_INSTRUCTIONS¶
This alignment block is further followed by num_element
length of block elements which may
consist of nested schedule blocks and schedule instructions.
Each schedule instruction starts with char
representing the instruction type
followed by the SEQUENCE block representing the instruction
operands
.
Note that the data structure of pulse Instruction
is unified so that instance can be uniquely determied by the class and a tuple of operands.
The mapping of type char to the instruction subclass is defined as follows:
a
:Acquire
instructionp
:Play
instructiond
:Delay
instructionf
:SetFrequency
instructiong
:ShiftFrequency
instructionq
:SetPhase
instructionr
:ShiftPhase
instructionb
:RelativeBarrier
instructiont
:TimeBlockade
instructiony
:Reference
instruction (new in version 0.7)
SCHEDULE_BLOCK_OPERANDS¶
The operands of these instances can be serialized through the standard QPY value serialization
mechanism, however there are special object types that only appear in the schedule operands.
Since the operands are serialized as SEQUENCE, each element must be packed with the
INSTRUCTION_PARAM pack struct, where each payload starts with a header block consists of
the char type
and uint64_t size
.
Special objects start with the following type key:
CHANNEL¶
Channel block starts with channel subtype char
that maps an object data to
Channel
subclass. Mapping is defined as follows:
d
:DriveChannel
e
:MemorySlot
r
:RegisterSlot
The key is immediately followed by the channel index serialized as the INSTRUCTION_PARAM.
Waveform¶
Waveform block starts with WAVEFORM header:
struct {
double epsilon;
uint32_t data_size;
_bool amp_limited;
}
which is followed by data_size
bytes of complex ndarray
binary generated by numpy.save.
This represents the complex IQ data points played on a quantum device.
name
is saved after the samples in the
INSTRUCTION_PARAM pack struct, which can be string or None
.
SymbolicPulse¶
SymbolicPulse block starts with SYMBOLIC_PULSE header:
struct {
uint16_t type_size;
uint16_t envelope_size;
uint16_t constraints_size;
uint16_t valid_amp_conditions_size;
_bool amp_limited;
}
which is followed by type_size
utf8 bytes of SymbolicPulse.pulse_type
string
that represents a class of waveform, such as «Gaussian» or «GaussianSquare».
Then, envelope_size
, constraints_size
, valid_amp_conditions_size
utf8 bytes of
serialized symbolic expressions are generated for SymbolicPulse.envelope
,
SymbolicPulse.constraints
, and SymbolicPulse.valid_amp_conditions
, respectively.
Since string representation of these expressions are usually lengthy,
the expression binary is generated by the python zlib module with data compression.
To uniquely specify a pulse instance, we also need to store the associated parameters,
which consist of duration
and the rest of parameters as a dictionary.
Dictionary parameters are first dumped in the MAPPING form, and then duration
is dumped with the INSTRUCTION_PARAM pack struct.
Lastly, name
is saved also with the
INSTRUCTION_PARAM pack struct, which can be string or None
.
MAPPING¶
The MAPPING is a representation for arbitrary mapping object. This is a fixed length SEQUENCE of key-value pair represented by the MAP_ITEM payload.
A MAP_ITEM starts with a header defined as:
struct {
uint16_t key_size;
char type;
uint16_t size;
}
which is immediately followed by the key_size
utf8 bytes representing
the dictionary key in string and size
utf8 bytes of arbitrary object data of
QPY serializable type
.
CIRCUIT_CALIBRATIONS¶
The CIRCUIT_CALIBRATIONS block is a dictionary to define pulse calibrations of the custom instruction set. This block starts with the following CALIBRATION header:
struct {
uint16_t num_cals;
}
which is followed by the num_cals
length of calibration entries, each starts with
the CALIBRATION_DEF header:
struct {
uint16_t name_size;
uint16_t num_qubits;
uint16_t num_params;
char type;
}
The calibration definition header is then followed by name_size
utf8 bytes of
the gate name, num_qubits
length of integers representing a sequence of qubits,
and num_params
length of INSTRUCTION_PARAM payload for parameters
associated to the custom instruction.
The type
indicates the class of pulse program which is either, in pricinple,
ScheduleBlock
or Schedule
. As of QPY Version 5,
only ScheduleBlock
payload is supported.
Finally, SCHEDULE_BLOCK payload is packed for each CALIBRATION_DEF entry.
INSTRUCTION¶
The INSTRUCTION block was modified to add two new fields num_ctrl_qubits
and ctrl_state
which are used to model the ControlledGate.num_ctrl_qubits
and
ControlledGate.ctrl_state
attributes. The new payload packed struct
format is:
struct {
uint16_t name_size;
uint16_t label_size;
uint16_t num_parameters;
uint32_t num_qargs;
uint32_t num_cargs;
_Bool has_conditional;
uint16_t conditional_reg_name_size;
int64_t conditional_value;
uint32_t num_ctrl_qubits;
uint32_t ctrl_state;
}
The rest of the instruction payload is the same. You can refer to INSTRUCTIONS for the details of the full payload.
CUSTOM_INSTRUCTION¶
The CUSTOM_INSTRUCTION block in QPY version 5 adds a new field
base_gate_size
which is used to define the size of the
qiskit.circuit.Instruction
object stored in the
ControlledGate.base_gate
attribute for a custom
ControlledGate
object. With this change the CUSTOM_INSTRUCTION
metadata block becomes:
struct {
uint16_t name_size;
char type;
uint32_t num_qubits;
uint32_t num_clbits;
_Bool custom_definition;
uint64_t size;
uint32_t num_ctrl_qubits;
uint32_t ctrl_state;
uint64_t base_gate_size
}
Immediately following the CUSTOM_INSTRUCTION struct is the utf8 encoded name
of size name_size
.
If custom_definition
is True
that means that the immediately following
size
bytes contains a QPY circuit data which can be used for the custom
definition of that gate. If custom_definition
is False
then the
instruction can be considered opaque (ie no definition). The type
field
determines what type of object will get created with the custom definition.
If it’s 'g'
it will be a Gate
object, 'i'
it will be a Instruction
object.
Following this the next base_gate_size
bytes contain the INSTRUCTION
payload for the ControlledGate.base_gate
.
Additionally an addition value for type
is added 'c'
which is used to
indicate the custom instruction is a custom ControlledGate
.
Version 4¶
Version 4 is identical to Version 3 except that it adds 2 new type strings
to the INSTRUCTION_PARAM struct, z
to represent None
(which is encoded as
no data), q
to represent a QuantumCircuit
(which is encoded as
a QPY circuit), r
to represent a range
of integers (which is encoded as
a RANGE), and t
to represent a sequence
(which is encoded as
defined by SEQUENCE). Additionally, version 4 changes the type of register
index mapping array from uint32_t
to int64_t
. If the values of any of the
array elements are negative they represent a register bit that is not present in the
circuit.
The REGISTERS header format has also been updated to
struct {
char type;
_Bool standalone;
uint32_t size;
uint16_t name_size;
_bool in_circuit;
}
which just adds the in_circuit
field which represents whether the register is
part of the circuit or not.
RANGE¶
A RANGE is a representation of a range
object. It is defined as:
struct {
int64_t start;
int64_t stop;
int64_t step;
}
SEQUENCE¶
A SEQUENCE is a reprentation of a arbitrary sequence object. As sequence are just fixed length
containers of arbitrary python objects their QPY can’t fully represent any sequence,
but as long as the contents in a sequence are other QPY serializable types for
the INSTRUCTION_PARAM payload the sequence
object can be serialized.
A sequence instruction parameter starts with a header defined as:
struct {
uint64_t size;
}
followed by size
elements that are INSTRUCTION_PARAM payloads, where each of
these define an element in the sequence. The sequence object will be typecasted
into proper type, e.g. tuple
, afterwards.
Version 3¶
Version 3 of the QPY format is identical to Version 2 except that it defines
a struct format to represent a PauliEvolutionGate
natively in QPY. To accomplish this the CUSTOM_DEFINITIONS struct now supports
a new type value 'p'
to represent a PauliEvolutionGate
.
Enties in the custom instructions tables have unique name generated that start with the
string "###PauliEvolutionGate_"
followed by a uuid string. This gate name is reservered
in QPY and if you have a custom Instruction
object with a definition
set and that name prefix it will error. If it’s of type 'p'
the data payload is defined
as follows:
PAULI_EVOLUTION¶
This represents the high level PauliEvolutionGate
struct {
uint64_t operator_count;
_Bool standalone_op;
char time_type;
uint64_t time_size;
uint64_t synthesis_size;
}
This is immediately followed by operator_count
elements defined by the SPARSE_PAULI_OP_LIST_ELEM
payload. Following that we have time_size
bytes representing the time
attribute. If
standalone_op
is True
then there must only be a single operator. The
encoding of these bytes is determined by the value of time_type
. Possible values of
time_type
are 'f'
, 'p'
, and 'e'
. If time_type
is 'f'
it’s a double,
'p'
defines a Parameter
object which is represented by a
PARAMETER, e
defines a ParameterExpression
object
(that’s not a Parameter
) which is represented by a PARAMETER_EXPR.
Following that is synthesis_size
bytes which is a utf8 encoded json payload representing
the EvolutionSynthesis
class used by the gate.
SPARSE_PAULI_OP_LIST_ELEM¶
This represents an instance of PauliSumOp
.
struct {
uint32_t pauli_op_size;
}
which is immediately followed by pauli_op_size
bytes which are .npy format 2
data which represents the SparsePauliOp
.
Version 3 of the QPY format also defines a struct format to represent a
ParameterVectorElement
as a distinct subclass from
a Parameter
. This adds a new parameter type char 'v'
to represent a ParameterVectorElement
which is now
supported as a type string value for an INSTRUCTION_PARAM. The payload for these
parameters are defined below as PARAMETER_VECTOR_ELEMENT.
PARAMETER_VECTOR_ELEMENT¶
A PARAMETER_VECTOR_ELEMENT represents a ParameterVectorElement
object the data for a INSTRUCTION_PARAM. The contents of the PARAMETER_VECTOR_ELEMENT are
defined as:
struct {
uint16_t vector_name_size;
uint64_t vector_size;
char uuid[16];
uint64_t index;
}
which is immediately followed by vector_name_size
utf8 bytes representing
the parameter’s vector name.
PARAMETER_EXPR¶
Additionally, since QPY format version v3 distinguishes between a
Parameter
and ParameterVectorElement
the payload for a ParameterExpression
needs to be updated
to distinguish between the types. The following is the modified payload format
which is mostly identical to the format in Version 1 and Version 2 but just
modifies the map_elements
struct to include a symbol type field.
A PARAMETER_EXPR represents a ParameterExpression
object that the data for an INSTRUCTION_PARAM. The contents of a PARAMETER_EXPR
are defined as:
struct {
uint64_t map_elements;
uint64_t expr_size;
}
Immediately following the header is expr_size
bytes of utf8 data containing
the expression string, which is the sympy srepr of the expression for the
parameter expression. Following that is a symbol map which contains
map_elements
elements with the format
struct {
char symbol_type;
char type;
uint64_t size;
}
The symbol_type
key determines the payload type of the symbol representation
for the element. If it’s p
it represents a Parameter
and if it’s v
it represents a ParameterVectorElement
.
The map element struct is immediately followed by the symbol map key payload, if
symbol_type
is p
then it is followed immediately by a PARAMETER
object (both the struct and utf8 name bytes) and if symbol_type
is v
then the struct is imediately followed by PARAMETER_VECTOR_ELEMENT (both the struct
and utf8 name bytes). That is followed by size
bytes for the
data of the symbol. The data format is dependent on the value of type
. If
type
is p
then it represents a Parameter
and
size will be 0, the value will just be the same as the key. Similarly if the
type
is v
then it represents a ParameterVectorElement
and size will be 0 as the value will just be the same as the key. If
type
is f
then it represents a double precision float. If type
is
c
it represents a double precision complex, which is represented by the
COMPLEX. Finally, if type is i
it represents an integer which is an
int64_t
.
Version 2¶
Version 2 of the QPY format is identical to version 1 except for the HEADER section is slightly different. You can refer to the Version 1 section for the details on the rest of the payload format.
HEADER¶
The contents of HEADER are defined as a C struct are:
struct {
uint16_t name_size;
char global_phase_type;
uint16_t global_phase_size;
uint32_t num_qubits;
uint32_t num_clbits;
uint64_t metadata_size;
uint32_t num_registers;
uint64_t num_instructions;
uint64_t num_custom_gates;
}
This is immediately followed by name_size
bytes of utf8 data for the name
of the circuit. Following this is immediately global_phase_size
bytes
representing the global phase. The content of that data is dictated by the
value of global_phase_type
. If it’s 'f'
the data is a float and is the
size of a double
. If it’s 'p'
defines a Parameter
object which is represented by a PARAM struct (see below), e
defines a
ParameterExpression
object (that’s not a
Parameter
) which is represented by a PARAM_EXPR struct
(see below).
Version 1¶
HEADER¶
The contents of HEADER as defined as a C struct are:
struct {
uint16_t name_size;
double global_phase;
uint32_t num_qubits;
uint32_t num_clbits;
uint64_t metadata_size;
uint32_t num_registers;
uint64_t num_instructions;
uint64_t num_custom_gates;
}
This is immediately followed by name_size
bytes of utf8 data for the name
of the circuit.
METADATA¶
The METADATA field is a UTF8 encoded JSON string. After reading the HEADER
(which is a fixed size at the start of the QPY file) and the name
string
you then read the metadata_size
number of bytes and parse the JSON to get
the metadata for the circuit.
REGISTERS¶
The contents of REGISTERS is a number of REGISTER object. If num_registers is > 0 then after reading METADATA you read that number of REGISTER structs defined as:
struct {
char type;
_Bool standalone;
uint32_t size;
uint16_t name_size;
}
type
can be 'q'
or 'c'
.
Immediately following the REGISTER struct is the utf8 encoded register name of
size name_size
. After the name
utf8 bytes there is then an array of
int64_t values of size size
that contains a map of the register’s index to
the circuit’s qubit index. For example, array element 0’s value is the index
of the register[0]
”s position in the containing circuit’s qubits list.
Nota
Prior to QPY Version 4 the type of array elements was uint32_t. This was changed to enable negative values which represent bits in the array not present in the circuit
The standalone boolean determines whether the register is constructed as a standalone register that was added to the circuit or was created from existing bits. A register is considered standalone if it has bits constructed solely as part of it, for example:
qr = QuantumRegister(2)
qc = QuantumCircuit(qr)
the register qr
would be a standalone register. While something like:
bits = [Qubit(), Qubit()]
qr2 = QuantumRegister(bits=bits)
qc = QuantumCircuit(qr2)
qr2
would have standalone
set to False
.
CUSTOM_DEFINITIONS¶
This section specifies custom definitions for any of the instructions in the circuit.
CUSTOM_DEFINITION_HEADER contents are defined as:
struct {
uint64_t size;
}
If size is greater than 0 that means the circuit contains custom instruction(s). Each custom instruction is defined with a CUSTOM_INSTRUCTION block defined as:
struct {
uint16_t name_size;
char type;
uint32_t num_qubits;
uint32_t num_clbits;
_Bool custom_definition;
uint64_t size;
}
Immediately following the CUSTOM_INSTRUCTION struct is the utf8 encoded name
of size name_size
.
If custom_definition
is True
that means that the immediately following
size
bytes contains a QPY circuit data which can be used for the custom
definition of that gate. If custom_definition
is False
then the
instruction can be considered opaque (ie no definition). The type
field
determines what type of object will get created with the custom definition.
If it’s 'g'
it will be a Gate
object, 'i'
it will be a Instruction
object.
INSTRUCTIONS¶
The contents of INSTRUCTIONS is a list of INSTRUCTION metadata objects
struct {
uint16_t name_size;
uint16_t label_size;
uint16_t num_parameters;
uint32_t num_qargs;
uint32_t num_cargs;
_Bool has_conditional;
uint16_t conditional_reg_name_size;
int64_t conditional_value;
}
This metadata object is immediately followed by name_size
bytes of utf8 bytes
for the name
. name
here is the Qiskit class name for the Instruction
class if it’s defined in Qiskit. Otherwise it falls back to the custom
instruction name. Following the name
bytes there are label_size
bytes of
utf8 data for the label if one was set on the instruction. Following the label
bytes if has_conditional
is True
then there are
conditional_reg_name_size
bytes of utf8 data for the name of the conditional
register name. In case of single classical bit conditions the register name
utf8 data will be prefixed with a null character «x00» and then a utf8 string
integer representing the classical bit index in the circuit that the condition
is on.
This is immediately followed by the INSTRUCTION_ARG structs for the list of arguments of that instruction. These are in the order of all quantum arguments (there are num_qargs of these) followed by all classical arguments (num_cargs of these).
The contents of each INSTRUCTION_ARG is:
struct {
char type;
uint32_t index;
}
type
can be 'q'
or 'c'
.
After all arguments for an instruction the parameters are specified with
num_parameters
INSTRUCTION_PARAM structs.
The contents of each INSTRUCTION_PARAM is:
struct {
char type;
uint64_t size;
}
After each INSTRUCTION_PARAM the next size
bytes are the parameter’s data.
The type
field can be 'i'
, 'f'
, 'p'
, 'e'
, 's'
, 'c'
or 'n'
which dictate the format. For 'i'
it’s an integer, 'f'
it’s
a double, 's'
if it’s a string (encoded as utf8), 'c'
is a complex and
the data is represented by the struct format in the PARAMETER_EXPR section.
'p'
defines a Parameter
object which is
represented by a PARAMETER struct, e
defines a
ParameterExpression
object (that’s not a
Parameter
) which is represented by a PARAMETER_EXPR
struct (on QPY format Version 3 the format is tweak slightly see:
PARAMETER_EXPR), 'n'
represents an object from numpy (either an
ndarray
or a numpy type) which means the data is .npy format 2 data,
and in QPY Version 3 'v'
represents a
ParameterVectorElement
which is represented by a
PARAMETER_VECTOR_ELEMENT struct.
PARAMETER¶
A PARAMETER represents a Parameter
object the data for
a INSTRUCTION_PARAM. The contents of the PARAMETER are defined as:
struct {
uint16_t name_size;
char uuid[16];
}
which is immediately followed by name_size
utf8 bytes representing the
parameter name.
PARAMETER_EXPR¶
A PARAMETER_EXPR represents a ParameterExpression
object that the data for an INSTRUCTION_PARAM. The contents of a PARAMETER_EXPR
are defined as:
The PARAMETER_EXPR data starts with a header:
struct {
uint64_t map_elements;
uint64_t expr_size;
}
Immediately following the header is expr_size
bytes of utf8 data containing
the expression string, which is the sympy srepr of the expression for the
parameter expression. Follwing that is a symbol map which contains
map_elements
elements with the format
struct {
char type;
uint64_t size;
}
Which is followed immediately by PARAMETER
object (both the struct and utf8
name bytes) for the symbol map key. That is followed by size
bytes for the
data of the symbol. The data format is dependent on the value of type
. If
type
is p
then it represents a Parameter
and
size will be 0, the value will just be the same as the key. If
type
is f
then it represents a double precision float. If type
is
c
it represents a double precision complex, which is represented by COMPLEX.
Finally, if type is i
it represents an integer which is an int64_t
.