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Get started with primitives

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New execution model, now in beta release

The beta release of a new execution model is now available. The directed execution model provides more flexibility when customizing your error mitigation workflow. See the Directed execution model guide for more information.

hinweis

While this documentation uses the primitives from Qiskit Runtime, which allow you to use IBM® backends, the primitives can be run on any provider by using the backend primitives instead. Additionally, you can use the reference primitives to run on a local statevector simulator. See Exact simulation with Qiskit primitives for details.

# Added by doQumentation — required packages for this notebook
!pip install -q numpy qiskit qiskit-ibm-runtime

The steps in this topic describe how to set up primitives, explore the options you can use to configure them, and invoke them in a program.

Using Fractional Gates

To use the newly supported fractional gates, set use_fractional_gates=True when requesting a backend from a QiskitRuntimeService instance. For example:

service = QiskitRuntimeService()
fractional_gate_backend = service.least_busy(use_fractional_gates=True)

Note that this is an experimental feature and might change in the future.

Package versions

The code on this page was developed using the following requirements. We recommend using these versions or newer.

qiskit[all]~=2.3.0
qiskit-ibm-runtime~=0.43.1

Get started with Estimator​

1. Initialize the account​

Because Qiskit Runtime Estimator is a managed service, you first need to initialize your account. You can then select the QPU you want to use to calculate the expectation value.

Follow the steps in the Install and set up topic if you don't already have an account.

from qiskit_ibm_runtime import QiskitRuntimeService

service = QiskitRuntimeService()
backend = service.least_busy(
    operational=True, simulator=False, min_num_qubits=127
)

print(backend.name)
ibm_torino

2. Create a circuit and an observable​

You need at least one circuit and one observable as inputs to the Estimator primitive.

from qiskit.circuit.library import qaoa_ansatz
from qiskit.quantum_info import SparsePauliOp

entanglement = [tuple(edge) for edge in backend.coupling_map.get_edges()]
observable = SparsePauliOp.from_sparse_list(
    [("ZZ", [i, j], 0.5) for i, j in entanglement],
    num_qubits=backend.num_qubits,
)
circuit = qaoa_ansatz(observable, reps=2)
# the circuit is parametrized, so we will define the parameter values for execution
param_values = [0.1, 0.2, 0.3, 0.4]

print(f">>> Observable: {observable.paulis}")
>>> Observable: ['IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...',
 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII...', ...]

The circuit and observable need to be transformed to only use instructions supported by the QPU (referred to as instruction set architecture (ISA) circuits). We'll use the transpiler to do this.

from qiskit.transpiler import generate_preset_pass_manager

pm = generate_preset_pass_manager(optimization_level=1, backend=backend)
isa_circuit = pm.run(circuit)
isa_observable = observable.apply_layout(isa_circuit.layout)
print(f">>> Circuit ops (ISA): {isa_circuit.count_ops()}")
>>> Circuit ops (ISA): OrderedDict([('rz', 3826), ('sx', 1601), ('cz', 968)])

3. Initialize Qiskit Runtime Estimator​

When you initialize the Estimator, use the mode parameter to specify the mode you want it to run in. Possible values are batch, session, or backend objects for batch, session, and job execution mode, respectively. For more information, see Introduction to Qiskit Runtime execution modes.

from qiskit_ibm_runtime import EstimatorV2 as Estimator

estimator = Estimator(mode=backend)

4. Invoke the Estimator and get results​

Next, invoke the run() method to calculate expectation values for the input circuits and observables. The circuit, observable, and optional parameter value sets are input as primitive unified bloc (PUB) tuples.

job = estimator.run([(isa_circuit, isa_observable, param_values)])
print(f">>> Job ID: {job.job_id()}")
print(f">>> Job Status: {job.status()}")
>>> Job ID: d5k96c4jt3vs73ds5smg
>>> Job Status: QUEUED
result = job.result()
print(f">>> {result}")
print(f"  > Expectation value: {result[0].data.evs}")
print(f"  > Metadata: {result[0].metadata}")
>>> PrimitiveResult([PubResult(data=DataBin(evs=np.ndarray(<shape=(), dtype=float64>), stds=np.ndarray(<shape=(), dtype=float64>), ensemble_standard_error=np.ndarray(<shape=(), dtype=float64>)), metadata={'shots': 4096, 'target_precision': 0.015625, 'circuit_metadata': {}, 'resilience': {}, 'num_randomizations': 32})], metadata={'dynamical_decoupling': {'enable': False, 'sequence_type': 'XX', 'extra_slack_distribution': 'middle', 'scheduling_method': 'alap'}, 'twirling': {'enable_gates': False, 'enable_measure': True, 'num_randomizations': 'auto', 'shots_per_randomization': 'auto', 'interleave_randomizations': True, 'strategy': 'active-accum'}, 'resilience': {'measure_mitigation': True, 'zne_mitigation': False, 'pec_mitigation': False}, 'version': 2})
  > Expectation value: 25.8930784649363
  > Metadata: {'shots': 4096, 'target_precision': 0.015625, 'circuit_metadata': {}, 'resilience': {}, 'num_randomizations': 32}

Get started with Sampler​

1. Initialize the account​

Because Qiskit Runtime Sampler is a managed service, you first need to initialize your account. You can then select the QPU you want to use to calculate the expectation value.

Follow the steps in the Install and set up topic if you don't already have an account set up.

from qiskit_ibm_runtime import QiskitRuntimeService

service = QiskitRuntimeService()
backend = service.least_busy(
    operational=True, simulator=False, min_num_qubits=127
)

2. Create a circuit​

You need at least one circuit as the input to the Sampler primitive.

import numpy as np
from qiskit.circuit.library import efficient_su2

circuit = efficient_su2(127, entanglement="linear")
circuit.measure_all()
# The circuit is parametrized, so we will define the parameter values for execution
param_values = np.random.rand(circuit.num_parameters)

Use the transpiler to get an ISA circuit.

from qiskit.transpiler import generate_preset_pass_manager

pm = generate_preset_pass_manager(optimization_level=1, backend=backend)
isa_circuit = pm.run(circuit)
print(f">>> Circuit ops (ISA): {isa_circuit.count_ops()}")
>>> Circuit ops (ISA): OrderedDict([('sx', 3089), ('rz', 3036), ('cz', 1092), ('measure', 127), ('barrier', 1)])

3. Initialize the Qiskit Runtime Sampler​

When you initialize the Sampler, use the mode parameter to specify the mode you want it to run in. Possible values are batch, session, or backend objects for batch, session, and job execution mode, respectively. For more information, see Introduction to Qiskit Runtime execution modes. Note that Open Plan users cannot submit session jobs.

from qiskit_ibm_runtime import SamplerV2 as Sampler

sampler = Sampler(mode=backend)

4. Invoke the Sampler and get results​

Next, invoke the run() method to generate the output. The circuit and optional parameter value sets are input as primitive unified bloc (PUB) tuples.

job = sampler.run([(isa_circuit, param_values)])
print(f">>> Job ID: {job.job_id()}")
print(f">>> Job Status: {job.status()}")
>>> Job ID: d5k96rsjt3vs73ds5tig
>>> Job Status: QUEUED
result = job.result()

# Get results for the first (and only) PUB
pub_result = result[0]
print(
    f"First ten results for the 'meas' output register: {pub_result.data.meas.get_bitstrings()[:10]}"
)
First ten results for the 'meas' output register: ['0101001101010000011001110001011000010010001100001000100110011111011110000010110001101000110011101010000100011011000110101111000', '0100111000000100110001100100000101111000111001101000110111101110110010010100001101001111001010011101010000010011000110000010001', '0101111101111111010011010101000000110100000010000010011101100011100011001100000100100001000101000000100001010101010011001101100', '1100110101111111001110010000010100101010101010001000001100100110011111010000000010001000110111010000010101100000100000110111001', '0010000001111001111010100100010111101000101000100000101100001000011100000100011010110110100011100110001001110110111101010011000', '0101110000001000100100010010100100111000010100000000010010000000010110010010000110000001110110010100000111001110100100111101100', '0100011111101001000111110011011101101101110101110001010111011101111110011101001000000001110000011110000101010000001010000100000', '0001010101011000110100000100111111100001011000111110000011000111001101010000010001001100000110000000100000110101010010101110010', '0100011010001110011110000110100101100100101001001111010100100101010100010000000010100000101010110010000000001000010101011111110', '0000011000000111000001000101111111110110101100110000001100010010011101011100001010000100011010001010001101000000000000010001001']

Get started with the backend primitives​

Unlike provider-specific primitives, backend primitives are generic implementations that can be used with an arbitrary backend object, as long as it implements the Backend interface.

Some providers implement primitives natively. See the Qiskit Ecosystem page for details.

Example: BackendEstimator​

from qiskit.primitives import BackendEstimatorV2
from <some_qiskit_provider> import QiskitProvider

provider = QiskitProvider()
backend = provider.get_backend('backend_name')
estimator = BackendEstimatorV2(backend)

Example: BackendSampler​

from qiskit.primitives import BackendSamplerV2
from <some_qiskit_provider> import QiskitProvider

provider = QiskitProvider()
backend = provider.get_backend('backend_name')
sampler = BackendSamplerV2(backend)

Similarities and differences between backend and Runtime primitives​

Next steps​

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