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---
title: StabilizerState (v1.2)
description: API reference for qiskit.quantum_info.StabilizerState in qiskit v1.2
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.quantum_info.StabilizerState
---
# StabilizerState
<Class id="qiskit.quantum_info.StabilizerState" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L32-L773" signature="qiskit.quantum_info.StabilizerState(data, validate=True)" modifiers="class">
Bases: `QuantumState`
StabilizerState class. Stabilizer simulator using the convention from reference \[1]. Based on the internal class [`Clifford`](qiskit.quantum_info.Clifford "qiskit.quantum_info.Clifford").
```python
from qiskit import QuantumCircuit
from qiskit.quantum_info import StabilizerState, Pauli
# Bell state generation circuit
qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
stab = StabilizerState(qc)
# Print the StabilizerState
print(stab)
# Calculate the StabilizerState measurement probabilities dictionary
print (stab.probabilities_dict())
# Calculate expectation value of the StabilizerState
print (stab.expectation_value(Pauli('ZZ')))
```
```python
StabilizerState(StabilizerTable: ['+XX', '+ZZ'])
{'00': 0.5, '11': 0.5}
1
```
Given a list of stabilizers, [`qiskit.quantum_info.StabilizerState.from_stabilizer_list()`](#qiskit.quantum_info.StabilizerState.from_stabilizer_list "qiskit.quantum_info.StabilizerState.from_stabilizer_list") returns a state stabilized by the list
```python
from qiskit.quantum_info import StabilizerState
stabilizer_list = ["ZXX", "-XYX", "+ZYY"]
stab = StabilizerState.from_stabilizer_list(stabilizer_list)
```
**References**
1. S. Aaronson, D. Gottesman, *Improved Simulation of Stabilizer Circuits*, Phys. Rev. A 70, 052328 (2004). [arXiv:quant-ph/0406196](https://arxiv.org/abs/quant-ph/0406196)
Initialize a StabilizerState object.
**Parameters**
* **or** (*data (*[*StabilizerState*](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState") *or*[*Clifford*](qiskit.quantum_info.Clifford "qiskit.quantum_info.Clifford") *or*[*Pauli*](qiskit.quantum_info.Pauli "qiskit.quantum_info.Pauli") *or*[*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")) qiskit.circuit.Instruction): Data from which the stabilizer state can be constructed.
* **validate** (*boolean*) validate that the stabilizer state data is a valid Clifford.
## Attributes
### clifford
<Attribute id="qiskit.quantum_info.StabilizerState.clifford">
Return StabilizerState Clifford data
</Attribute>
### dim
<Attribute id="qiskit.quantum_info.StabilizerState.dim">
Return total state dimension.
</Attribute>
### num\_qubits
<Attribute id="qiskit.quantum_info.StabilizerState.num_qubits">
Return the number of qubits if a N-qubit state or None otherwise.
</Attribute>
## Methods
### conjugate
<Function id="qiskit.quantum_info.StabilizerState.conjugate" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L191-L195" signature="conjugate()">
Return the conjugate of the operator.
</Function>
### copy
<Function id="qiskit.quantum_info.StabilizerState.copy" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/quantum_state.py#L74-L76" signature="copy()">
Make a copy of current operator.
</Function>
### dims
<Function id="qiskit.quantum_info.StabilizerState.dims" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/quantum_state.py#L70-L72" signature="dims(qargs=None)">
Return tuple of input dimension for specified subsystems.
</Function>
### equiv
<Function id="qiskit.quantum_info.StabilizerState.equiv" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L322-L361" signature="equiv(other)">
Return True if the two generating sets generate the same stabilizer group.
**Parameters**
**other** ([*StabilizerState*](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")) another StabilizerState.
**Returns**
True if other has a generating set that generates the same StabilizerState.
**Return type**
[bool](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")
</Function>
### evolve
<Function id="qiskit.quantum_info.StabilizerState.evolve" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L233-L255" signature="evolve(other, qargs=None)">
Evolve a stabilizer state by a Clifford operator.
**Parameters**
* **other** ([*Clifford*](qiskit.quantum_info.Clifford "qiskit.quantum_info.Clifford") *or*[*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") *or*[*qiskit.circuit.Instruction*](qiskit.circuit.Instruction "qiskit.circuit.Instruction")) The Clifford operator to evolve by.
* **qargs** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) a list of stabilizer subsystem positions to apply the operator on.
**Returns**
the output stabilizer state.
**Return type**
[StabilizerState](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")
**Raises**
* [**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if other is not a StabilizerState.
* [**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if the operator dimension does not match the specified StabilizerState subsystem dimensions.
</Function>
### expand
<Function id="qiskit.quantum_info.StabilizerState.expand" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L215-L231" signature="expand(other)">
Return the tensor product stabilizer state other ⊗ self.
**Parameters**
**other** ([*StabilizerState*](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")) a stabilizer state object.
**Returns**
the tensor product operator other ⊗ self.
**Return type**
[StabilizerState](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")
**Raises**
[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if other is not a StabilizerState.
</Function>
### expectation\_value
<Function id="qiskit.quantum_info.StabilizerState.expectation_value" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L257-L320" signature="expectation_value(oper, qargs=None)">
Compute the expectation value of a Pauli operator.
**Parameters**
* **oper** ([*Pauli*](qiskit.quantum_info.Pauli "qiskit.quantum_info.Pauli")) a Pauli operator to evaluate expval.
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to apply the operator on.
**Returns**
the expectation value (only 0 or 1 or -1 or i or -i).
**Return type**
[complex](https://docs.python.org/3/library/functions.html#complex "(in Python v3.13)")
**Raises**
[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if oper is not a Pauli operator.
</Function>
### from\_stabilizer\_list
<Function id="qiskit.quantum_info.StabilizerState.from_stabilizer_list" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L108-L136" signature="from_stabilizer_list(stabilizers, allow_redundant=False, allow_underconstrained=False)" modifiers="classmethod">
Create a stabilizer state from the collection of stabilizers.
**Parameters**
* **stabilizers** (*Collection\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")*]*) list of stabilizer strings
* **allow\_redundant** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")) allow redundant stabilizers (i.e., some stabilizers can be products of the others)
* **allow\_underconstrained** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")) allow underconstrained set of stabilizers (i.e., the stabilizers do not specify a unique state)
**Returns**
a state stabilized by stabilizers.
**Return type**
[StabilizerState](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")
</Function>
### is\_valid
<Function id="qiskit.quantum_info.StabilizerState.is_valid" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L149-L151" signature="is_valid(atol=None, rtol=None)">
Return True if a valid StabilizerState.
</Function>
### measure
<Function id="qiskit.quantum_info.StabilizerState.measure" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L486-L514" signature="measure(qargs=None)">
Measure subsystems and return outcome and post-measure state.
Note that this function uses the QuantumStates internal random number generator for sampling the measurement outcome. The RNG seed can be set using the [`seed()`](#qiskit.quantum_info.StabilizerState.seed "qiskit.quantum_info.StabilizerState.seed") method.
**Parameters**
**qargs** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)") *or None*) subsystems to sample measurements for, if None sample measurement of all subsystems (Default: None).
**Returns**
**the pair `(outcome, state)` where `outcome` is the**
measurement outcome string label, and `state` is the collapsed post-measurement stabilizer state for the corresponding outcome.
**Return type**
[tuple](https://docs.python.org/3/library/stdtypes.html#tuple "(in Python v3.13)")
</Function>
### probabilities
<Function id="qiskit.quantum_info.StabilizerState.probabilities" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L363-L387" signature="probabilities(qargs=None, decimals=None)">
Return the subsystem measurement probability vector.
Measurement probabilities are with respect to measurement in the computation (diagonal) basis.
**Parameters**
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to return probabilities for, if None return for all subsystems (Default: None).
* **decimals** (*None or* [*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) the number of decimal places to round values. If None no rounding is done (Default: None).
**Returns**
The Numpy vector array of probabilities.
**Return type**
np.array
</Function>
### probabilities\_dict
<Function id="qiskit.quantum_info.StabilizerState.probabilities_dict" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L425-L447" signature="probabilities_dict(qargs=None, decimals=None)">
Return the subsystem measurement probability dictionary.
Measurement probabilities are with respect to measurement in the computation (diagonal) basis.
This dictionary representation uses a Ket-like notation where the dictionary keys are qudit strings for the subsystem basis vectors. If any subsystem has a dimension greater than 10 comma delimiters are inserted between integers so that subsystems can be distinguished.
**Parameters**
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to return probabilities for, if None return for all subsystems (Default: None).
* **decimals** (*None or* [*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) the number of decimal places to round values. If None no rounding is done (Default: None).
**Returns**
The measurement probabilities in dict (key) form.
**Return type**
[dict](https://docs.python.org/3/library/stdtypes.html#dict "(in Python v3.13)")
</Function>
### probabilities\_dict\_from\_bitstring
<Function id="qiskit.quantum_info.StabilizerState.probabilities_dict_from_bitstring" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L389-L423" signature="probabilities_dict_from_bitstring(outcome_bitstring, qargs=None, decimals=None)">
Return the subsystem measurement probability dictionary utilizing a targeted outcome\_bitstring to perform the measurement for. This will calculate a probability for only a single targeted outcome\_bitstring value, giving a performance boost over calculating all possible outcomes.
Measurement probabilities are with respect to measurement in the computation (diagonal) basis.
This dictionary representation uses a Ket-like notation where the dictionary keys are qudit strings for the subsystem basis vectors. If any subsystem has a dimension greater than 10 comma delimiters are inserted between integers so that subsystems can be distinguished.
**Parameters**
* **outcome\_bitstring** (*None or* [*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")) targeted outcome bitstring to perform a measurement calculation for, this will significantly reduce the number of calculation performed (Default: None)
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to return probabilities for, if None return for all subsystems (Default: None).
* **decimals** (*None or* [*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) the number of decimal places to round values. If None no rounding is done (Default: None)
**Returns**
The measurement probabilities in dict (ket) form.
**Return type**
[dict](https://docs.python.org/3/library/stdtypes.html#dict "(in Python v3.13)")\[[str](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)"), [float](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)")]
</Function>
### purity
<Function id="qiskit.quantum_info.StabilizerState.purity" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L173-L185" signature="purity()">
Return the purity of the quantum state, which equals to 1, since it is always a pure state.
**Returns**
the purity (should equal 1).
**Return type**
[float](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)")
**Raises**
[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if input is not a StabilizerState.
</Function>
### reset
<Function id="qiskit.quantum_info.StabilizerState.reset" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L449-L484" signature="reset(qargs=None)">
Reset state or subsystems to the 0-state.
**Parameters**
**qargs** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)") *or None*) subsystems to reset, if None all subsystems will be reset to their 0-state (Default: None).
**Returns**
the reset state.
**Return type**
[StabilizerState](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")
**Additional Information:**
If all subsystems are reset this will return the ground state on all subsystems. If only some subsystems are reset this function will perform a measurement on those subsystems and evolve the subsystems so that the collapsed post-measurement states are rotated to the 0-state. The RNG seed for this sampling can be set using the [`seed()`](#qiskit.quantum_info.StabilizerState.seed "qiskit.quantum_info.StabilizerState.seed") method.
</Function>
### sample\_counts
<Function id="qiskit.quantum_info.StabilizerState.sample_counts" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/quantum_state.py#L277-L304" signature="sample_counts(shots, qargs=None)">
Sample a dict of qubit measurement outcomes in the computational basis.
**Parameters**
* **shots** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) number of samples to generate.
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to sample measurements for, if None sample measurement of all subsystems (Default: None).
**Returns**
sampled counts dictionary.
**Return type**
[Counts](qiskit.result.Counts "qiskit.result.Counts")
Additional Information:
> This function *samples* measurement outcomes using the measure [`probabilities()`](#qiskit.quantum_info.StabilizerState.probabilities "qiskit.quantum_info.StabilizerState.probabilities") for the current state and qargs. It does not actually implement the measurement so the current state is not modified.
>
> The seed for random number generator used for sampling can be set to a fixed value by using the stats [`seed()`](#qiskit.quantum_info.StabilizerState.seed "qiskit.quantum_info.StabilizerState.seed") method.
</Function>
### sample\_memory
<Function id="qiskit.quantum_info.StabilizerState.sample_memory" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L516-L540" signature="sample_memory(shots, qargs=None)">
Sample a list of qubit measurement outcomes in the computational basis.
**Parameters**
* **shots** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) number of samples to generate.
* **qargs** (*None or* [*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")) subsystems to sample measurements for, if None sample measurement of all subsystems (Default: None).
**Returns**
list of sampled counts if the order sampled.
**Return type**
np.array
Additional Information:
> This function implements the measurement [`measure()`](#qiskit.quantum_info.StabilizerState.measure "qiskit.quantum_info.StabilizerState.measure") method.
>
> The seed for random number generator used for sampling can be set to a fixed value by using the stats [`seed()`](#qiskit.quantum_info.StabilizerState.seed "qiskit.quantum_info.StabilizerState.seed") method.
</Function>
### seed
<Function id="qiskit.quantum_info.StabilizerState.seed" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/quantum_state.py#L78-L85" signature="seed(value=None)">
Set the seed for the quantum state RNG.
</Function>
### tensor
<Function id="qiskit.quantum_info.StabilizerState.tensor" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L197-L213" signature="tensor(other)">
Return the tensor product stabilizer state self ⊗ other.
**Parameters**
**other** ([*StabilizerState*](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")) a stabilizer state object.
**Returns**
the tensor product operator self ⊗ other.
**Return type**
[StabilizerState](#qiskit.quantum_info.StabilizerState "qiskit.quantum_info.StabilizerState")
**Raises**
[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if other is not a StabilizerState.
</Function>
### to\_operator
<Function id="qiskit.quantum_info.StabilizerState.to_operator" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L187-L189" signature="to_operator()">
Convert state to matrix operator class
**Return type**
[*Operator*](qiskit.quantum_info.Operator "qiskit.quantum_info.operators.operator.Operator")
</Function>
### trace
<Function id="qiskit.quantum_info.StabilizerState.trace" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/quantum_info/states/stabilizerstate.py#L159-L171" signature="trace()">
Return the trace of the stabilizer state as a density matrix, which equals to 1, since it is always a pure state.
**Returns**
the trace (should equal 1).
**Return type**
[float](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)")
**Raises**
[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") if input is not a StabilizerState.
</Function>
</Class>