---
title: Port code to Qiskit Serverless
description: How to port existing code to leverage Qiskit Serverless
source: https://eu-de.quantum.cloud.ibm.com/docs/en/guides/serverless-port-code
---

# Port code to Qiskit Serverless

> **Tip**
>
> **Qiskit Serverless is getting an upgrade, and its features are changing fast.** During this development phase, find release notes and the most recent documentation at the [Qiskit Serverless GitHub](https://qiskit.github.io/qiskit-serverless/index.html) page.

The following example demonstrates how to port existing code to leverage Qiskit Serverless.

> **Note**
>
> The following code assumes that you have saved your credentials. If you have not, follow the instructions in [Set up your IBM Cloud account](/docs/guides/cloud-setup-untrusted) to authenticate with your API key.

## Update the experiment

### Local Experiment

```python
from qiskit.transpiler import generate_preset_pass_manager
from qiskit_ibm_runtime import QiskitRuntimeService
from qiskit.circuit.random import random_circuit

qc_random = [(random_circuit(20, 20, measure=True)) for _ in range(30)]
optimization_level = 3

service = QiskitRuntimeService(channel="ibm_quantum_platform")
backend = service.get_backend(backend_name)

pass_manager = generate_preset_pass_manager(
    optimization_level=optimization_level, backend=backend
)

# @distribute_task(target={"cpu": 1})
def transpile_parallel(circuit, pass_manager):
    """Distributed transpilation for an abstract circuit into an ISA circuit for a given backend."""

    isa_circuit = pass_manager.run(circuit)

    return isa_circuit

transpiled_circuits = [
    transpile_parallel(circuit, pass_manager)
    for circuit in circuits
]

print(transpiled_circuits)
```

### Serverless

```python
# transpile_remote.py

from qiskit.transpiler import generate_preset_pass_manager
from qiskit_serverless import get_arguments, save_result, distribute_task, get
from qiskit_ibm_runtime import QiskitRuntimeService

# Get program arguments
arguments = get_arguments()
circuits = arguments.get("circuits")
backend_name = arguments.get("backend_name")
optimization_level = arguments.get("optimization_level")
pass_manager = generate_preset_pass_manager(
optimization_level=optimization_level, backend=backend_name
)

# Distribute task across workers
@distribute_task(target={"cpu": 1})
def transpile_parallel(circuit, pass_manager):
"""Distributed transpilation for an abstract circuit into an ISA circuit for a given backend."""

isa_circuit = pass_manager.run(circuit)

return isa_circuit

try:
# Get backend
service = QiskitRuntimeService()
backend = service.get_backend(backend_name)

# run distributed tasks as async function
# we get task references as a return type
sample_task_references = [
    transpile_parallel(circuit, pass_manager)
    for circuit in circuits
]

# now we need to collect results from task references
results = get(sample_task_references)

# Return results
save_result({
    "transpiled_circuits": results
})

except Exception as e:
# Exception handling
import traceback
print(traceback.format_exc())
```

## Upload to Qiskit Serverless

Follow the instructions on the [Introduction to Qiskit Functions](/docs/guides/functions) page to authenticate with your API key.

```python
from qiskit_ibm_catalog import QiskitServerless, QiskitFunction

# Authenticate to the remote cluster and submit the pattern for remote execution.
serverless = QiskitServerless()

transpile_remote_demo = QiskitFunction(
    title="transpile_remote_serverless",
    entrypoint="transpile_remote.py",
    working_dir="./source_files/",
)

serverless.upload(transpile_remote_demo)
```

Output

```text
'transpile_remote_serverless'
```

## Remotely run in Qiskit Serverless

```python
from qiskit.circuit.random import random_circuit
from qiskit_ibm_runtime import QiskitRuntimeService

# Setup inputs
qc_random = [(random_circuit(20, 20, measure=True)) for _ in range(30)]
backend = "ibm_brisbane"
optimization_level = 3

# Running program
transpile_remote_serverless = serverless.load('transpile_remote_serverless')
job = transpile_remote_serverless.run(
    circuits=qc_random,
    backend=backend,
    optimization_level=optimization_level
)

job.job_id
```

Output

```text
'727e921d-512d-4b7d-af97-fe29e93ce7ea'
```

## Next steps

> **Recommendations**
>
> - Read a paper in which researchers used Qiskit Serverless and quantum-centric supercomputing to [explore quantum chemistry](https://arxiv.org/abs/2405.05068v1).