This quick start runs your first quantum circuit — a two-qubit Bell state — on the QCOS built-in simulator. Use the simulator first, then promote the same workflow to a QPU backend after cost approval.

Before you run your first quantum circuit

Before starting, ensure QCOS and all environment variables are correctly set up on your machine.

For OS-specific setup, shell path persistence, and CLI binary downloads, follow the Installation Guide.
If you are running locally vs. cloud, review the Open-Core / Hybrid Cloud Setup.

Once your environment is set up:

export QCOS_API_URL="https://api.softquantus.com"
export QCOS_API_KEY="sqt_live_your_key"

Run a quantum circuit with the QCOS REST API

curl -X POST "$QCOS_API_URL/api/v1/jobs/" \
  -H "Authorization: Bearer $QCOS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "circuit": {
      "qasm": "OPENQASM 2.0;\ninclude \"qelib1.inc\";\nqreg q[2];\ncreg c[2];\nh q[0];\ncx q[0],q[1];\nmeasure q[0] -> c[0];\nmeasure q[1] -> c[1];",
      "format": "qasm2"
    },
    "backend": "simulator_aer",
    "shots": 1024
  }'

Poll status:

curl "$QCOS_API_URL/api/v1/jobs/job_abc123" \
  -H "Authorization: Bearer $QCOS_API_KEY"

Retrieve results:

curl "$QCOS_API_URL/api/v1/jobs/job_abc123/results" \
  -H "Authorization: Bearer $QCOS_API_KEY"

Run a quantum circuit with the QCOS Python SDK

pip install softqcos-sdk

import os
from softqcos_sdk import QCOSClient

client = QCOSClient(
    api_key=os.environ["QCOS_API_KEY"],
    base_url=os.getenv("QCOS_API_URL", "https://api.softquantus.com"),
)

bell_qasm = """OPENQASM 2.0;
include "qelib1.inc";
qreg q[2];
creg c[2];
h q[0];
cx q[0],q[1];
measure q[0] -> c[0];
measure q[1] -> c[1];"""

job = client.jobs.submit(
    circuit={"qasm": bell_qasm, "format": "qasm2"},
    backend="simulator_aer",
    shots=1024
)
print(job)

Run a quantum circuit with the QCOS CLI

pip install softqcos
softqcos login --api-key "$QCOS_API_KEY" --api-url "$QCOS_API_URL"
softqcos run bell.qasm --backend simulator_aer --shots 1024

Start

QCOS quick start: how to run a quantum circuit

Before you run your first quantum circuit

Run a quantum circuit with the QCOS REST API

Run a quantum circuit with the QCOS Python SDK

Run a quantum circuit with the QCOS CLI

Next steps

Authentication

Backends

​Before you run your first quantum circuit

​Run a quantum circuit with the QCOS REST API

​Run a quantum circuit with the QCOS Python SDK

​Run a quantum circuit with the QCOS CLI

​Next steps

Authentication

Backends

Before you run your first quantum circuit

Run a quantum circuit with the QCOS REST API

Run a quantum circuit with the QCOS Python SDK

Run a quantum circuit with the QCOS CLI

Next steps