---
title: TwoLocal (v2.0)
description: API reference for qiskit.circuit.library.TwoLocal in qiskit v2.0
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/2.0/qiskit.circuit.library.TwoLocal
---

# TwoLocal

*class* `qiskit.circuit.library.TwoLocal(num_qubits=None, rotation_blocks=None, entanglement_blocks=None, entanglement='full', reps=3, skip_unentangled_qubits=False, skip_final_rotation_layer=False, parameter_prefix='θ', insert_barriers=False, initial_state=None, name='TwoLocal', flatten=None)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.0/qiskit/circuit/library/n_local/two_local.py#L30-L289)

Bases: [`NLocal`](/docs/api/qiskit/2.0/qiskit.circuit.library.NLocal "qiskit.circuit.library.n_local.n_local.NLocal")

The two-local circuit.

The two-local circuit is a parameterized circuit consisting of alternating rotation layers and entanglement layers. The rotation layers are single qubit gates applied on all qubits. The entanglement layer uses two-qubit gates to entangle the qubits according to a strategy set using `entanglement`. Both the rotation and entanglement gates can be specified as string (e.g. `'ry'` or `'cx'`), as gate-type (e.g. `RYGate` or `CXGate`) or as QuantumCircuit (e.g. a 1-qubit circuit or 2-qubit circuit).

A set of default entanglement strategies is provided:

- `'full'` entanglement is each qubit is entangled with all the others.
- `'linear'` entanglement is qubit $i$ entangled with qubit $i + 1$, for all $i \in \{0, 1, ... , n - 2\}$, where $n$ is the total number of qubits.
- `'reverse_linear'` entanglement is qubit $i$ entangled with qubit $i + 1$, for all $i \in \{n-2, n-3, ... , 1, 0\}$, where $n$ is the total number of qubits. Note that if `entanglement_blocks = 'cx'` then this option provides the same unitary as `'full'` with fewer entangling gates.
- `'pairwise'` entanglement is one layer where qubit $i$ is entangled with qubit $i + 1$, for all even values of $i$, and then a second layer where qubit $i$ is entangled with qubit $i + 1$, for all odd values of $i$.
- `'circular'` entanglement is linear entanglement but with an additional entanglement of the first and last qubit before the linear part.
- `'sca'` (shifted-circular-alternating) entanglement is a generalized and modified version of the proposed circuit 14 in [Sim et al.](https://arxiv.org/abs/1905.10876). It consists of circular entanglement where the ‘long’ entanglement connecting the first with the last qubit is shifted by one each block. Furthermore the role of control and target qubits are swapped every block (therefore alternating).

The entanglement can further be specified using an entangler map, which is a list of index pairs, such as

```python
>>> entangler_map = [(0, 1), (1, 2), (2, 0)]
```

If different entanglements per block should be used, provide a list of entangler maps. See the examples below on how this can be used.

```python
>>> entanglement = [entangler_map_layer_1, entangler_map_layer_2, ... ]
```

Barriers can be inserted in between the different layers for better visualization using the `insert_barriers` attribute.

For each parameterized gate a new parameter is generated using a `ParameterVector`. The name of these parameters can be chosen using the `parameter_prefix`.

**Examples**

```python
>>> two = TwoLocal(3, 'ry', 'cx', 'linear', reps=2, insert_barriers=True)
>>> print(two.decompose())  # decompose the layers into standard gates
     ┌──────────┐ ░            ░ ┌──────────┐ ░            ░ ┌──────────┐
q_0: ┤ Ry(θ[0]) ├─░───■────────░─┤ Ry(θ[3]) ├─░───■────────░─┤ Ry(θ[6]) ├
     ├──────────┤ ░ ┌─┴─┐      ░ ├──────────┤ ░ ┌─┴─┐      ░ ├──────────┤
q_1: ┤ Ry(θ[1]) ├─░─┤ X ├──■───░─┤ Ry(θ[4]) ├─░─┤ X ├──■───░─┤ Ry(θ[7]) ├
     ├──────────┤ ░ └───┘┌─┴─┐ ░ ├──────────┤ ░ └───┘┌─┴─┐ ░ ├──────────┤
q_2: ┤ Ry(θ[2]) ├─░──────┤ X ├─░─┤ Ry(θ[5]) ├─░──────┤ X ├─░─┤ Ry(θ[8]) ├
     └──────────┘ ░      └───┘ ░ └──────────┘ ░      └───┘ ░ └──────────┘
```

```python
>>> two = TwoLocal(3, ['ry','rz'], 'cz', 'full', reps=1, insert_barriers=True, flatten=True)
>>> qc = QuantumCircuit(3)
>>> qc &= two
>>> print(qc.draw())
     ┌──────────┐┌──────────┐ ░           ░ ┌──────────┐ ┌──────────┐
q_0: ┤ Ry(θ[0]) ├┤ Rz(θ[3]) ├─░──■──■─────░─┤ Ry(θ[6]) ├─┤ Rz(θ[9]) ├
     ├──────────┤├──────────┤ ░  │  │     ░ ├──────────┤┌┴──────────┤
q_1: ┤ Ry(θ[1]) ├┤ Rz(θ[4]) ├─░──■──┼──■──░─┤ Ry(θ[7]) ├┤ Rz(θ[10]) ├
     ├──────────┤├──────────┤ ░     │  │  ░ ├──────────┤├───────────┤
q_2: ┤ Ry(θ[2]) ├┤ Rz(θ[5]) ├─░─────■──■──░─┤ Ry(θ[8]) ├┤ Rz(θ[11]) ├
     └──────────┘└──────────┘ ░           ░ └──────────┘└───────────┘
```

```python
>>> entangler_map = [[0, 1], [1, 2], [2, 0]]  # circular entanglement for 3 qubits
>>> two = TwoLocal(3, 'x', 'crx', entangler_map, reps=1, flatten=True)
>>> print(two)  # note: no barriers inserted this time!
        ┌───┐                             ┌──────────┐┌───┐
q_0: |0>┤ X ├─────■───────────────────────┤ Rx(θ[2]) ├┤ X ├
        ├───┤┌────┴─────┐            ┌───┐└─────┬────┘└───┘
q_1: |0>┤ X ├┤ Rx(θ[0]) ├─────■──────┤ X ├──────┼──────────
        ├───┤└──────────┘┌────┴─────┐└───┘      │     ┌───┐
q_2: |0>┤ X ├────────────┤ Rx(θ[1]) ├───────────■─────┤ X ├
        └───┘            └──────────┘                 └───┘
```

```python
>>> entangler_map = [[0, 3], [0, 2]]  # entangle the first and last two-way
>>> two = TwoLocal(4, [], 'cry', entangler_map, reps=1, flatten=True)
>>> circuit = two.compose(two)
>>> print(circuit.draw())  # note, that the parameters are the same!
q_0: ─────■───────────■───────────■───────────■──────
          │           │           │           │
q_1: ─────┼───────────┼───────────┼───────────┼──────
          │      ┌────┴─────┐     │      ┌────┴─────┐
q_2: ─────┼──────┤ Ry(θ[1]) ├─────┼──────┤ Ry(θ[1]) ├
     ┌────┴─────┐└──────────┘┌────┴─────┐└──────────┘
q_3: ┤ Ry(θ[0]) ├────────────┤ Ry(θ[0]) ├────────────
     └──────────┘            └──────────┘
```

```python
>>> layer_1 = [(0, 1), (0, 2)]
>>> layer_2 = [(1, 2)]
>>> two = TwoLocal(3, 'x', 'cx', [layer_1, layer_2], reps=2, insert_barriers=True,
... flatten=True)
>>> print(two)
     ┌───┐ ░            ░ ┌───┐ ░       ░ ┌───┐
q_0: ┤ X ├─░───■────■───░─┤ X ├─░───────░─┤ X ├
     ├───┤ ░ ┌─┴─┐  │   ░ ├───┤ ░       ░ ├───┤
q_1: ┤ X ├─░─┤ X ├──┼───░─┤ X ├─░───■───░─┤ X ├
     ├───┤ ░ └───┘┌─┴─┐ ░ ├───┤ ░ ┌─┴─┐ ░ ├───┤
q_2: ┤ X ├─░──────┤ X ├─░─┤ X ├─░─┤ X ├─░─┤ X ├
     └───┘ ░      └───┘ ░ └───┘ ░ └───┘ ░ └───┘
```

> **Deprecated since version 1.3\_pending**
>
> The class `qiskit.circuit.library.n_local.two_local.TwoLocal` is pending deprecation as of Qiskit 1.3. It will be marked deprecated in a future release, and then removed no earlier than 3 months after the release date. Use the function qiskit.circuit.library.n\_local instead.

**Parameters**

- **num\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int) *| None*) – The number of qubits of the two-local circuit.
- **rotation\_blocks** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*type*](https://docs.python.org/3/library/functions.html#type)  *|*[*qiskit.circuit.Instruction*](/docs/api/qiskit/2.0/qiskit.circuit.Instruction "qiskit.circuit.Instruction")  *|*[*QuantumCircuit*](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")  *|*[*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*type*](https://docs.python.org/3/library/functions.html#type)  *|*[*qiskit.circuit.Instruction*](/docs/api/qiskit/2.0/qiskit.circuit.Instruction "qiskit.circuit.Instruction")  *|*[*QuantumCircuit*](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")*] | None*) – The gates used in the rotation layer. Can be specified via the name of a gate (e.g. `'ry'`) or the gate type itself (e.g. [`RYGate`](/docs/api/qiskit/2.0/qiskit.circuit.library.RYGate "qiskit.circuit.library.RYGate")). If only one gate is provided, the gate same gate is applied to each qubit. If a list of gates is provided, all gates are applied to each qubit in the provided order. See the Examples section for more detail.
- **entanglement\_blocks** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*type*](https://docs.python.org/3/library/functions.html#type)  *|*[*qiskit.circuit.Instruction*](/docs/api/qiskit/2.0/qiskit.circuit.Instruction "qiskit.circuit.Instruction")  *|*[*QuantumCircuit*](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")  *|*[*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*type*](https://docs.python.org/3/library/functions.html#type)  *|*[*qiskit.circuit.Instruction*](/docs/api/qiskit/2.0/qiskit.circuit.Instruction "qiskit.circuit.Instruction")  *|*[*QuantumCircuit*](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")*] | None*) – The gates used in the entanglement layer. Can be specified in the same format as `rotation_blocks`.
- **entanglement** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*]] | Callable\[\[*[*int*](https://docs.python.org/3/library/functions.html#int)*],* [*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*]]*) – Specifies the entanglement structure. Can be a string (`'full'`, `'linear'`, `'reverse_linear'`, `'circular'` or `'sca'`), a list of integer-pairs specifying the indices of qubits entangled with one another, or a callable returning such a list provided with the index of the entanglement layer. Default to `'full'` entanglement. Note that if `entanglement_blocks = 'cx'`, then `'full'` entanglement provides the same unitary as `'reverse_linear'` but the latter option has fewer entangling gates. See the Examples section for more detail.
- **reps** ([*int*](https://docs.python.org/3/library/functions.html#int)) – Specifies how often a block consisting of a rotation layer and entanglement layer is repeated.
- **skip\_unentangled\_qubits** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – If `True`, the single qubit gates are only applied to qubits that are entangled with another qubit. If `False`, the single qubit gates are applied to each qubit in the ansatz. Defaults to `False`.
- **skip\_final\_rotation\_layer** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – If `False`, a rotation layer is added at the end of the ansatz. If `True`, no rotation layer is added.
- **parameter\_prefix** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) – The parameterized gates require a parameter to be defined, for which we use instances of [`Parameter`](/docs/api/qiskit/2.0/qiskit.circuit.Parameter "qiskit.circuit.Parameter"). The name of each parameter will be this specified prefix plus its index.
- **insert\_barriers** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – If `True`, barriers are inserted in between each layer. If `False`, no barriers are inserted. Defaults to `False`.
- **initial\_state** ([*QuantumCircuit*](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") *| None*) – A [`QuantumCircuit`](/docs/api/qiskit/2.0/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") object to prepend to the circuit.
- **flatten** ([*bool*](https://docs.python.org/3/library/functions.html#bool) *| None*) – Set this to `True` to output a flat circuit instead of nesting it inside multiple layers of gate objects. By default currently the contents of the output circuit will be wrapped in nested objects for cleaner visualization. However, if you’re using this circuit for anything besides visualization its **strongly** recommended to set this flag to `True` to avoid a large performance overhead for parameter binding.
- **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) –

## Attributes

### ancillas

A list of `AncillaQubit`s in the order that they were added. You should not mutate this.

### clbits

A list of `Clbit`s in the order that they were added. You should not mutate this.

**Example**

```python
from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit

qr1 = QuantumRegister(2)
qr2 = QuantumRegister(1)
cr1 = ClassicalRegister(2)
cr2 = ClassicalRegister(1)
qc = QuantumCircuit(qr1, qr2, cr1, cr2)

print("List the qubits in this circuit:", qc.qubits)
print("List the classical bits in this circuit:", qc.clbits)
```

```text
List the qubits in this circuit: [Qubit(QuantumRegister(2, 'q0'), 0),
Qubit(QuantumRegister(2, 'q0'), 1), Qubit(QuantumRegister(1, 'q1'), 0)]
List the classical bits in this circuit: [Clbit(ClassicalRegister(2, 'c0'), 0),
Clbit(ClassicalRegister(2, 'c0'), 1), Clbit(ClassicalRegister(1, 'c1'), 0)]
```

### cregs

A list of `Clbit`s in the order that they were added. You should not mutate this.

### data

The circuit data (instructions and context).

**Returns**

a list-like object containing the [`CircuitInstruction`](/docs/api/qiskit/2.0/qiskit.circuit.CircuitInstruction "qiskit.circuit.CircuitInstruction")s for each instruction.

**Return type**

QuantumCircuitData

### duration

The total duration of the circuit, set by a scheduling transpiler pass. Its unit is specified by [`unit`](#qiskit.circuit.library.TwoLocal.unit "qiskit.circuit.library.TwoLocal.unit").

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.quantumcircuit.QuantumCircuit.duration` is deprecated as of Qiskit 1.3.0. It will be removed in Qiskit 3.0.0.

### entanglement

Get the entanglement strategy.

**Returns**

The entanglement strategy, see [`get_entangler_map()`](#qiskit.circuit.library.TwoLocal.get_entangler_map "qiskit.circuit.library.TwoLocal.get_entangler_map") for more detail on how the format is interpreted.

### entanglement\_blocks

The blocks in the entanglement layers.

**Returns**

The blocks in the entanglement layers.

### flatten

Returns whether the circuit is wrapped in nested gates/instructions or flattened.

### global\_phase

The global phase of the current circuit scope in radians.

**Example**

```python
from qiskit import QuantumCircuit

circuit = QuantumCircuit(2)
circuit.h(0)
circuit.cx(0, 1)
print(circuit.global_phase)
```

```text
0.0
```

```python
from numpy import pi

circuit.global_phase = pi/4
print(circuit.global_phase)
```

```text
0.7853981633974483
```

### initial\_state

Return the initial state that is added in front of the n-local circuit.

**Returns**

The initial state.

### insert\_barriers

If barriers are inserted in between the layers or not.

**Returns**

`True`, if barriers are inserted in between the layers, `False` if not.

### instances

Default value: `174`

### layout

Return any associated layout information about the circuit.

This attribute contains an optional [`TranspileLayout`](/docs/api/qiskit/2.0/qiskit.transpiler.TranspileLayout "qiskit.transpiler.TranspileLayout") object. This is typically set on the output from [`transpile()`](/docs/api/qiskit/2.0/compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") or [`PassManager.run()`](/docs/api/qiskit/2.0/qiskit.transpiler.PassManager#run "qiskit.transpiler.PassManager.run") to retain information about the permutations caused on the input circuit by transpilation.

There are two types of permutations caused by the [`transpile()`](/docs/api/qiskit/2.0/compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") function: an initial layout that permutes the qubits based on the selected physical qubits on the [`Target`](/docs/api/qiskit/2.0/qiskit.transpiler.Target "qiskit.transpiler.Target"), and a final layout, which is an output permutation caused by [`SwapGate`](/docs/api/qiskit/2.0/qiskit.circuit.library.SwapGate "qiskit.circuit.library.SwapGate")s inserted during routing.

**Example**

```python
from qiskit import QuantumCircuit
from qiskit.providers.fake_provider import GenericBackendV2
from qiskit.transpiler import generate_preset_pass_manager

# Create circuit to test transpiler on
qc = QuantumCircuit(3, 3)
qc.h(0)
qc.cx(0, 1)
qc.swap(1, 2)
qc.cx(0, 1)

# Add measurements to the circuit
qc.measure([0, 1, 2], [0, 1, 2])

# Specify the QPU to target
backend = GenericBackendV2(3)

# Transpile the circuit
pass_manager = generate_preset_pass_manager(
optimization_level=1, backend=backend
)
transpiled = pass_manager.run(qc)

# Print the layout after transpilation
print(transpiled.layout.routing_permutation())
```

```text
[0, 1, 2]
```

### metadata

Arbitrary user-defined dictionary of metadata for the circuit.

Qiskit will not examine the content of this mapping, but it will pass it through the transpiler and reattach it to the output, so you can track your own metadata.

**Example**

```python
from qiskit import QuantumCircuit

qc = QuantumCircuit(2, 2, metadata={'experiment_type': 'Bell state experiment'})

print(qc.metadata)
```

```text
{'experiment_type': 'Bell state experiment'}
```

### num\_ancillas

Return the number of ancilla qubits.

**Example**

```python
from qiskit import QuantumCircuit, QuantumRegister, AncillaRegister

# Create a 2-qubit quantum circuit
reg = QuantumRegister(2)
qc = QuantumCircuit(reg)

# Create an ancilla register with 1 qubit
anc = AncillaRegister(1)
qc.add_register(anc)  # Add the ancilla register to the circuit

print("Number of ancilla qubits:", qc.num_ancillas)
```

```text
Number of ancilla qubits: 1
```

### num\_captured\_stretches

The number of stretches in the circuit marked as captured from an enclosing scope.

This is the length of the `iter_captured_stretches()` iterable. If this is non-zero, [`num_input_vars`](#qiskit.circuit.library.TwoLocal.num_input_vars "qiskit.circuit.library.TwoLocal.num_input_vars") must be zero.

### num\_captured\_vars

The number of real-time classical variables in the circuit marked as captured from an enclosing scope.

This is the length of the `iter_captured_vars()` iterable. If this is non-zero, [`num_input_vars`](#qiskit.circuit.library.TwoLocal.num_input_vars "qiskit.circuit.library.TwoLocal.num_input_vars") must be zero.

### num\_clbits

Return number of classical bits.

**Example**

```python
from qiskit import QuantumCircuit

# Create a new circuit with two qubits and one classical bit
qc = QuantumCircuit(2, 1)
print("Number of classical bits:", qc.num_clbits)
```

```text
Number of classical bits: 1
```

### num\_declared\_stretches

The number of stretches in the circuit that are declared by this circuit scope, excluding captures.

This is the length of the `iter_declared_stretches()` iterable.

### num\_declared\_vars

The number of real-time classical variables in the circuit that are declared by this circuit scope, excluding inputs or captures.

This is the length of the `iter_declared_vars()` iterable.

### num\_identifiers

The number of real-time classical variables and stretches in the circuit.

This is equal to [`num_vars()`](#qiskit.circuit.library.TwoLocal.num_vars "qiskit.circuit.library.TwoLocal.num_vars") + [`num_stretches()`](#qiskit.circuit.library.TwoLocal.num_stretches "qiskit.circuit.library.TwoLocal.num_stretches").

### num\_input\_vars

The number of real-time classical variables in the circuit marked as circuit inputs.

This is the length of the `iter_input_vars()` iterable. If this is non-zero, [`num_captured_vars`](#qiskit.circuit.library.TwoLocal.num_captured_vars "qiskit.circuit.library.TwoLocal.num_captured_vars") must be zero.

### num\_layers

Return the number of layers in the n-local circuit.

**Returns**

The number of layers in the circuit.

### num\_parameters

The number of parameter objects in the circuit.

### 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`](/docs/api/qiskit/2.0/qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects currently in the circuit.

**Returns**

The number of parameters originally available in the circuit.

> **Note**
>
> This quantity does not require the circuit to be built yet.

### num\_qubits

Returns the number of qubits in this circuit.

**Returns**

The number of qubits.

### num\_stretches

The number of stretches in the circuit.

This is the length of the `iter_stretches()` iterable.

### num\_vars

The number of real-time classical variables in the circuit.

This is the length of the `iter_vars()` iterable.

### op\_start\_times

Return a list of operation start times.

> **Note**
>
> This attribute computes the estimate starting time of the operations in the scheduled circuit and only works for simple circuits that have no control flow or other classical feed-forward operations.

This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.

**Example**

```python
from qiskit import QuantumCircuit
from qiskit.providers.fake_provider import GenericBackendV2
from qiskit.transpiler import generate_preset_pass_manager

qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()

# Print the original circuit
print("Original circuit:")
print(qc)

# Transpile the circuit with a specific basis gates list and print the resulting circuit
backend = GenericBackendV2(2, basis_gates=['u1', 'u2', 'u3', 'cx'])
pm = generate_preset_pass_manager(
    optimization_level=1, backend=backend, scheduling_method="alap"
)
transpiled_qc = pm.run(qc)
print("Transpiled circuit with basis gates ['u1', 'u2', 'u3', 'cx']:")
print(transpiled_qc)

# Print the start times of each instruction in the transpiled circuit
print("Start times of instructions in the transpiled circuit:")
for instruction, start_time in zip(transpiled_qc.data, transpiled_qc.op_start_times):
    print(f"{instruction.operation.name}: {start_time}")
```

```text
Original circuit:
        ┌───┐      ░ ┌─┐
q_0: ┤ H ├──■───░─┤M├───
        └───┘┌─┴─┐ ░ └╥┘┌─┐
q_1: ─────┤ X ├─░──╫─┤M├
            └───┘ ░  ║ └╥┘
meas: 2/══════════════╩══╩═
                    0  1

Transpiled circuit with basis gates ['u1', 'u2', 'u3', 'cx']:
            ┌─────────┐          ░ ┌─────────────────┐┌─┐
q_0 -> 0 ───┤ U2(0,π) ├──────■───░─┤ Delay(1255[dt]) ├┤M├
        ┌──┴─────────┴───┐┌─┴─┐ ░ └───────┬─┬───────┘└╥┘
q_1 -> 1 ┤ Delay(196[dt]) ├┤ X ├─░─────────┤M├─────────╫─
        └────────────────┘└───┘ ░         └╥┘         ║
meas: 2/═══════════════════════════════════╩══════════╩═
                                            1          0

Start times of instructions in the transpiled circuit:
u2: 0
delay: 0
cx: 196
barrier: 2098
delay: 2098
measure: 3353
measure: 2098
```

**Returns**

List of integers representing instruction estimated start times. The index corresponds to the index of instruction in `QuantumCircuit.data`.

**Raises**

[**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError) – When circuit is not scheduled.

### ordered\_parameters

The parameters used in the underlying circuit.

This includes float values and duplicates.

**Examples**

```python
>>> # 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])]
```

**Returns**

The parameters objects used in the circuit.

### parameter\_bounds

The parameter bounds for the unbound parameters in the circuit.

**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

The parameters defined in the circuit.

This attribute returns the [`Parameter`](/docs/api/qiskit/2.0/qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects in the circuit sorted alphabetically. Note that parameters instantiated with a [`ParameterVector`](/docs/api/qiskit/2.0/qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector") are still sorted numerically.

**Examples**

The snippet below shows that insertion order of parameters does not matter.

```python
>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> a, b, elephant = Parameter("a"), Parameter("b"), Parameter("elephant")
>>> circuit = QuantumCircuit(1)
>>> circuit.rx(b, 0)
>>> circuit.rz(elephant, 0)
>>> circuit.ry(a, 0)
>>> circuit.parameters  # sorted alphabetically!
ParameterView([Parameter(a), Parameter(b), Parameter(elephant)])
```

Bear in mind that alphabetical sorting might be unintuitive when it comes to numbers. The literal “10” comes before “2” in strict alphabetical sorting.

```python
>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> angles = [Parameter("angle_1"), Parameter("angle_2"), Parameter("angle_10")]
>>> circuit = QuantumCircuit(1)
>>> circuit.u(*angles, 0)
>>> circuit.draw()
   ┌─────────────────────────────┐
q: ┤ U(angle_1,angle_2,angle_10) ├
   └─────────────────────────────┘
>>> circuit.parameters
ParameterView([Parameter(angle_1), Parameter(angle_10), Parameter(angle_2)])
```

To respect numerical sorting, a [`ParameterVector`](/docs/api/qiskit/2.0/qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector") can be used.

```python
>>> from qiskit.circuit import QuantumCircuit, Parameter, ParameterVector
>>> x = ParameterVector("x", 12)
>>> circuit = QuantumCircuit(1)
>>> for x_i in x:
...     circuit.rx(x_i, 0)
>>> circuit.parameters
ParameterView([
    ParameterVectorElement(x[0]), ParameterVectorElement(x[1]),
    ParameterVectorElement(x[2]), ParameterVectorElement(x[3]),
    ..., ParameterVectorElement(x[11])
])
```

**Returns**

The sorted [`Parameter`](/docs/api/qiskit/2.0/qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects in the circuit.

### preferred\_init\_points

The initial points for the parameters. Can be stored as initial guess in optimization.

**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

A list of `Qubit`s in the order that they were added. You should not mutate this.

### reps

The number of times rotation and entanglement block are repeated.

**Returns**

The number of repetitions.

### rotation\_blocks

The blocks in the rotation layers.

**Returns**

The blocks in the rotation layers.

### unit

The unit that [`duration`](#qiskit.circuit.library.TwoLocal.duration "qiskit.circuit.library.TwoLocal.duration") is specified in.

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.quantumcircuit.QuantumCircuit.unit` is deprecated as of Qiskit 1.3.0. It will be removed in Qiskit 3.0.0.

### name

Type: `str`

A human-readable name for the circuit.

**Example**

```python
from qiskit import QuantumCircuit

qc = QuantumCircuit(2, 2, name="my_circuit")
print(qc.name)
```

```text
my_circuit
```

## Methods

### get\_entangler\_map

`get_entangler_map(rep_num, block_num, num_block_qubits)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.0/qiskit/circuit/library/n_local/two_local.py#L283-L289)

Overloading to handle the special case of 1 qubit where the entanglement are ignored.

**Parameters**

- **rep\_num** ([*int*](https://docs.python.org/3/library/functions.html#int)) –
- **block\_num** ([*int*](https://docs.python.org/3/library/functions.html#int)) –
- **num\_block\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int)) –

**Return type**

[*Sequence*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Sequence)\[[*Sequence*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Sequence)\[[int](https://docs.python.org/3/library/functions.html#int)]]