NLocal
class NLocal(num_qubits=None, rotation_blocks=None, entanglement_blocks=None, entanglement=None, reps=1, insert_barriers=False, parameter_prefix='θ', overwrite_block_parameters=True, skip_final_rotation_layer=False, skip_unentangled_qubits=False, initial_state=None, name='nlocal')
Bases: qiskit.circuit.library.blueprintcircuit.BlueprintCircuit
The n-local circuit class.
The structure of the n-local circuit are alternating rotation and entanglement layers. In both layers, parameterized circuit-blocks act on the circuit in a defined way. In the rotation layer, the blocks are applied stacked on top of each other, while in the entanglement layer according to the entanglement strategy. The circuit blocks can have arbitrary sizes (smaller equal to the number of qubits in the circuit). Each layer is repeated reps times, and by default a final rotation layer is appended.
For instance, a rotation block on 2 qubits and an entanglement block on 4 qubits using 'linear' entanglement yields the following circuit.
┌──────┐ ░ ┌──────┐ ░ ┌──────┐
┤0 ├─░─┤0 ├──────────────── ... ─░─┤0 ├
│ Rot │ ░ │ │┌──────┐ ░ │ Rot │
┤1 ├─░─┤1 ├┤0 ├──────── ... ─░─┤1 ├
├──────┤ ░ │ Ent ││ │┌──────┐ ░ ├──────┤
┤0 ├─░─┤2 ├┤1 ├┤0 ├ ... ─░─┤0 ├
│ Rot │ ░ │ ││ Ent ││ │ ░ │ Rot │
┤1 ├─░─┤3 ├┤2 ├┤1 ├ ... ─░─┤1 ├
├──────┤ ░ └──────┘│ ││ Ent │ ░ ├──────┤
┤0 ├─░─────────┤3 ├┤2 ├ ... ─░─┤0 ├
│ Rot │ ░ └──────┘│ │ ░ │ Rot │
┤1 ├─░─────────────────┤3 ├ ... ─░─┤1 ├
└──────┘ ░ └──────┘ ░ └──────┘
| |
+---------------------------------+
repeated reps timesIf specified, barriers can be inserted in between every block. If an initial state object of Qiskit Aqua is provided, it is added in front of the NLocal.
Create a new n-local circuit.
Parameters
- num_qubits (
Optional[int]) – The number of qubits of the circuit. - rotation_blocks (
Union[QuantumCircuit,List[QuantumCircuit],Instruction,List[Instruction],None]) – The blocks used in the rotation layers. If multiple are passed, these will be applied one after another (like new sub-layers). - entanglement_blocks (
Union[QuantumCircuit,List[QuantumCircuit],Instruction,List[Instruction],None]) – The blocks used in the entanglement layers. If multiple are passed, these will be applied one after another. To use different entanglements for the sub-layers, seeget_entangler_map(). - entanglement (
Union[List[int],List[List[int]],None]) – The indices specifying on which qubits the input blocks act. If None, the entanglement blocks are applied at the top of the circuit. - reps (
int) – Specifies how often the rotation blocks and entanglement blocks are repeated. - insert_barriers (
bool) – If True, barriers are inserted in between each layer. If False, no barriers are inserted. - parameter_prefix (
str) – The prefix used if default parameters are generated. - overwrite_block_parameters (
Union[bool,List[List[Parameter]]]) – If the parameters in the added blocks should be overwritten. If False, the parameters in the blocks are not changed. - skip_final_rotation_layer (
bool) – Whether a final rotation layer is added to the circuit. - skip_unentangled_qubits (
bool) – IfTrue, the rotation gates act only on qubits that are entangled. IfFalse, the rotation gates act on all qubits. - initial_state (
Optional[Any]) – A QuantumCircuit object which can be used to describe an initial state prepended to the NLocal circuit. - name (
Optional[str]) – The name of the circuit.
Examples
TODO
Raises
- ImportError – If an
initial_stateis specified but Qiskit Aqua is not installed. - ValueError – If reps parameter is less than or equal to 0.
- TypeError – If reps parameter is not an int value.
Methods Defined Here
add_layer
NLocal.add_layer(other, entanglement=None, front=False)
Append another layer to the NLocal.
Parameters
- other (
Union[NLocal,Instruction,QuantumCircuit]) – The layer to compose, can be another NLocal, an Instruction or Gate, or a QuantumCircuit. - entanglement (
Union[List[int],str,List[List[int]],None]) – The entanglement or qubit indices. - front (
bool) – If True,otheris appended to the front, else to the back.
Return type
NLocal
Returns
self, such that chained composes are possible.
Raises
TypeError – If other is not compatible, i.e. is no Instruction and does not have a to_instruction method.
assign_parameters
NLocal.assign_parameters(parameters, inplace=False)
Assign parameters to the n-local circuit.
This method also supports passing a list instead of a dictionary. If a list is passed, the list must have the same length as the number of unbound parameters in the circuit. The parameters are assigned in the order of the parameters in ordered_parameters().
Return type
Optional[QuantumCircuit]
Returns
A copy of the NLocal circuit with the specified parameters.
Raises
AttributeError – If the parameters are given as list and do not match the number of parameters.
get_entangler_map
NLocal.get_entangler_map(rep_num, block_num, num_block_qubits)
Get the entangler map for in the repetition rep_num and the block block_num.
The entangler map for the current block is derived from the value of self.entanglement. Below the different cases are listed, where i and j denote the repetition number and the block number, respectively, and n the number of qubits in the block.
entanglement type | entangler map ——————————-+——————————————————– None | [[0, …, n - 1]] str (e.g ‘full’) | the specified connectivity on n qubits List[int] | [entanglement] List[List[int]] | entanglement List[List[List[int]]] | entanglement[i] List[List[List[List[int]]]] | entanglement[i][j] List[str] | the connectivity specified in entanglement[i] List[List[str]] | the connectivity specified in entanglement[i][j] Callable[int, str] | same as List[str] Callable[int, List[List[int]]] | same as List[List[List[int]]]
Note that all indices are to be taken modulo the length of the array they act on, i.e. no out-of-bounds index error will be raised but we re-iterate from the beginning of the list.
Parameters
- rep_num (
int) – The current repetition we are in. - block_num (
int) – The block number within the entanglement layers. - num_block_qubits (
int) – The number of qubits in the block.
Return type
List[List[int]]
Returns
The entangler map for the current block in the current repetition.
Raises
ValueError – If the value of entanglement could not be cast to a corresponding entangler map.
get_unentangled_qubits
NLocal.get_unentangled_qubits()
Get the indices of unentangled qubits in a set.
Return type
Set[int]
Returns
The unentangled qubits.
print_settings
NLocal.print_settings()
Returns information about the setting.
Return type
str
Returns
The class name and the attributes/parameters of the instance as str.
Attributes
ancillas
Returns a list of ancilla bits in the order that the registers were added.
Return type
List[AncillaQubit]
calibrations
Return calibration dictionary.
The custom pulse definition of a given gate is of the form
{‘gate_name’: {(qubits, params): schedule}}
Return type
dict
clbits
Returns a list of classical bits in the order that the registers were added.
Return type
List[Clbit]
data
entanglement
Get the entanglement strategy.
Return type
Union[str, List[str], List[List[str]], List[int], List[List[int]], List[List[List[int]]], List[List[List[List[int]]]], Callable[[int], str], Callable[[int], List[List[int]]]]
Returns
The entanglement strategy, see get_entangler_map() for more detail on how the format is interpreted.
entanglement_blocks
The blocks in the entanglement layers.
Return type
List[Instruction]
Returns
The blocks in the entanglement layers.
extension_lib
Default value: 'include "qelib1.inc";'
global_phase
Return the global phase of the circuit in radians.
Return type
Union[ParameterExpression, float]
header
Default value: 'OPENQASM 2.0;'
initial_state
Return the initial state that is added in front of the n-local circuit.
Return type
Any
Returns
The initial state.
insert_barriers
If barriers are inserted in between the layers or not.
Return type
bool
Returns
True, if barriers are inserted in between the layers, False if not.
instances
Default value: 9
metadata
The user provided metadata associated with the circuit
The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.
Return type
dict
num_ancillas
Return the number of ancilla qubits.
Return type
int
num_clbits
Return number of classical bits.
Return type
int
num_layers
Return the number of layers in the n-local circuit.
Return type
int
Returns
The number of layers in the circuit.
num_parameters
Return type
int
num_parameters_settable
The number of total parameters that can be set to distinct values.
This does not change when the parameters are bound or exchanged for same parameters, and therefore is different from num_parameters which counts the number of unique Parameter objects currently in the circuit.
Return type
int
Returns
The number of parameters originally available in the circuit.
This quantity does not require the circuit to be built yet.
num_qubits
Returns the number of qubits in this circuit.
Return type
int
Returns
The number of qubits.
ordered_parameters
The parameters used in the underlying circuit.
This includes float values and duplicates.
Examples
>>> # prepare circuit ...
>>> print(nlocal)
┌───────┐┌──────────┐┌──────────┐┌──────────┐
q_0: ┤ Ry(1) ├┤ Ry(θ[1]) ├┤ Ry(θ[1]) ├┤ Ry(θ[3]) ├
└───────┘└──────────┘└──────────┘└──────────┘
>>> nlocal.parameters
{Parameter(θ[1]), Parameter(θ[3])}
>>> nlocal.ordered_parameters
[1, Parameter(θ[1]), Parameter(θ[1]), Parameter(θ[3])]Return type
List[Parameter]
Returns
The parameters objects used in the circuit.
parameter_bounds
The parameter bounds for the unbound parameters in the circuit.
Return type
Optional[List[Tuple[float, float]]]
Returns
A list of pairs indicating the bounds, as (lower, upper). None indicates an unbounded parameter in the corresponding direction. If None is returned, problem is fully unbounded.
parameters
Return type
ParameterView
preferred_init_points
The initial points for the parameters. Can be stored as initial guess in optimization.
Return type
Optional[List[float]]
Returns
The initial values for the parameters, or None, if none have been set.
prefix
Default value: 'circuit'
qregs
A list of the quantum registers associated with the circuit.
qubits
Returns a list of quantum bits in the order that the registers were added.
Return type
List[Qubit]
reps
The number of times rotation and entanglement block are repeated.
Return type
int
Returns
The number of repetitions.
rotation_blocks
The blocks in the rotation layers.
Return type
List[Instruction]
Returns
The blocks in the rotation layers.