373 lines
12 KiB
Plaintext
373 lines
12 KiB
Plaintext
---
|
||
title: StabilizerState
|
||
description: API reference for qiskit.quantum_info.StabilizerState
|
||
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/0.18/qiskit/quantum_info/states/stabilizerstate.py" signature="StabilizerState(data, validate=True)" modifiers="class">
|
||
Bases: `qiskit.quantum_info.states.quantum_state.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
|
||
```
|
||
|
||
**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**
|
||
|
||
* \*\*(****StabilizerState**** or ****Clifford**** or ****Pauli**** or \*\***QuantumCircuit or** (*data*) – qiskit.circuit.Instruction): Data from which the stabilizer state can be constructed.
|
||
* **validate** (*boolean*) – validate that the stabilizer state data is a valid Clifford.
|
||
|
||
## Methods
|
||
|
||
### conjugate
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.conjugate" signature="StabilizerState.conjugate()">
|
||
Return the conjugate of the operator.
|
||
</Function>
|
||
|
||
### copy
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.copy" signature="StabilizerState.copy()">
|
||
Make a copy of current operator.
|
||
</Function>
|
||
|
||
### dims
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.dims" signature="StabilizerState.dims(qargs=None)">
|
||
Return tuple of input dimension for specified subsystems.
|
||
</Function>
|
||
|
||
### evolve
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.evolve" signature="StabilizerState.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*) – 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** – if other is not a StabilizerState.
|
||
* **QiskitError** – if the operator dimension does not match the specified StabilizerState subsystem dimensions.
|
||
</Function>
|
||
|
||
### expand
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.expand" signature="StabilizerState.expand(other)">
|
||
Return the tensor product stabilzier 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** – if other is not a StabilizerState.
|
||
</Function>
|
||
|
||
### expectation\_value
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.expectation_value" signature="StabilizerState.expectation_value(oper, qargs=None)">
|
||
Compute the expectation value of an operator.
|
||
|
||
**Parameters**
|
||
|
||
* **oper** (*BaseOperator*) – an operator to evaluate expval.
|
||
* **qargs** (*None or list*) – subsystems to apply the operator on.
|
||
|
||
**Returns**
|
||
|
||
the expectation value (only 0 or 1 or -1).
|
||
|
||
**Return type**
|
||
|
||
complex
|
||
</Function>
|
||
|
||
### is\_valid
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.is_valid" signature="StabilizerState.is_valid(atol=None, rtol=None)">
|
||
Return True if a valid StabilizerState.
|
||
</Function>
|
||
|
||
### measure
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.measure" signature="StabilizerState.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 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
|
||
</Function>
|
||
|
||
### probabilities
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.probabilities" signature="StabilizerState.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*) – subsystems to return probabilities for, if None return for all subsystems (Default: None).
|
||
* **decimals** (*None or int*) – 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" signature="StabilizerState.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*) – subsystems to return probabilities for, if None return for all subsystems (Default: None).
|
||
* **decimals** (*None or int*) – 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
|
||
</Function>
|
||
|
||
### purity
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.purity" signature="StabilizerState.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**
|
||
|
||
double
|
||
|
||
**Raises**
|
||
|
||
**QiskitError** – if input is not a StabilizerState.
|
||
</Function>
|
||
|
||
### reset
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.reset" signature="StabilizerState.reset(qargs=None)">
|
||
Reset state or subsystems to the 0-state.
|
||
|
||
**Parameters**
|
||
|
||
**qargs** (*list 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" signature="StabilizerState.sample_counts(shots, qargs=None)">
|
||
Sample a dict of qubit measurement outcomes in the computational basis.
|
||
|
||
**Parameters**
|
||
|
||
* **shots** (*int*) – number of samples to generate.
|
||
* **qargs** (*None or list*) – 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" signature="StabilizerState.sample_memory(shots, qargs=None)">
|
||
Sample a list of qubit measurement outcomes in the computational basis.
|
||
|
||
**Parameters**
|
||
|
||
* **shots** (*int*) – number of samples to generate.
|
||
* **qargs** (*None or list*) – 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" signature="StabilizerState.seed(value=None)">
|
||
Set the seed for the quantum state RNG.
|
||
</Function>
|
||
|
||
### tensor
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.tensor" signature="StabilizerState.tensor(other)">
|
||
Return the tensor product stabilzier 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** – if other is not a StabilizerState.
|
||
</Function>
|
||
|
||
### to\_operator
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.to_operator" signature="StabilizerState.to_operator()">
|
||
Convert state to matrix operator class
|
||
</Function>
|
||
|
||
### trace
|
||
|
||
<Function id="qiskit.quantum_info.StabilizerState.trace" signature="StabilizerState.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**
|
||
|
||
double
|
||
|
||
**Raises**
|
||
|
||
**QiskitError** – if input is not a StabilizerState.
|
||
</Function>
|
||
|
||
## 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>
|
||
</Class>
|
||
|