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Frequently Asked Questions

General​

What is QCOS Core?​

QCOS Core is a quantum circuit optimization system that reduces the number of evaluations needed for variational quantum algorithms by 5-10x compared to standard approaches.

What backends are supported?​

ProviderBackends
IonQionq_simulator, ionq_qpu
Quantinuumquantinuum_h1, quantinuum_h2
IBMibm_brisbane, ibm_kyoto, ibm_osaka
Rigettirigetti_qvm, rigetti_aspen
AWS Braketbraket_sv1, braket_dm1, braket_tn1
Azure Quantumazure_ionq, azure_quantinuum
Localaer_simulator, qiskit_aer

What is the pricing model?​

See Pricing for details. We offer:

  • Free Tier: 1,000 evaluations/month
  • Pro: $99/month, 50,000 evaluations
  • Enterprise: Custom pricing

Technical​

How does QCOS achieve the speedup?​

QCOS uses several techniques:

  1. Surrogate Modeling: ML models predict circuit outcomes
  2. Adaptive Sampling: Focus evaluations on promising regions
  3. Noise-Aware Optimization: Account for hardware noise
  4. Autopilot Selection: Match algorithm to problem scale

What is the Glass-Box feature?​

Glass-Box provides full transparency into optimization decisions:

result = client.optimize(circuit, enable_glass_box=True)
print(result.glass_box.decisions)  # All optimization decisions
print(result.glass_box.reasoning)  # Why each decision was made

How does the Evidence system work?​

Every computation produces cryptographic evidence:

  • SHA-256 hash of inputs and outputs
  • Ed25519 or Dilithium signature
  • Timestamp and backend metadata
  • Stored for audit and verification

Can I run QCOS on-premise?​

Yes, Enterprise customers can deploy QCOS on-premise or in private cloud. Contact sales@softquantus.com.

Troubleshooting​

My optimization is slow​

  1. Check your backend choice - simulators are faster
  2. Reduce circuit complexity
  3. Use appropriate autopilot for your scale
  4. Enable surrogate modeling

I'm getting authentication errors​

# Verify API key
export QCOS_API_KEY="your-key"
softqcos auth verify

# Check key permissions
softqcos auth permissions

Backend not available​

Some backends have limited availability:

Evidence verification failed​

  1. Ensure the evidence bundle is complete
  2. Check that public keys are correct
  3. Verify the hash matches the computation
from softqcos import verify_evidence
result = verify_evidence(evidence_bundle)
print(result.valid)  # True/False
print(result.details)  # Verification details

Integration​

How do I integrate with my existing quantum code?​

QCOS accepts standard QASM and Qiskit circuits:

# From Qiskit
from qiskit import QuantumCircuit
qc = QuantumCircuit(4)
qc.h(0)
qc.cx(0, 1)

result = client.optimize(circuit=qc)

Does QCOS work with PennyLane?​

Yes, via the PennyLane-QCOS plugin:

import pennylane as qml

dev = qml.device("qcos.ionq", wires=4)

@qml.qnode(dev)
def circuit():
    qml.Hadamard(0)
    qml.CNOT([0, 1])
    return qml.expval(qml.PauliZ(0))

Can I use QCOS in a CI/CD pipeline?​

Yes, QCOS CLI supports automation:

# GitHub Actions example
- name: Run quantum optimization
  run: |
    softqcos optimize --circuit circuit.qasm --output results.json
    softqcos verify --evidence results.json

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