Support

Welcome to the Classiq Support Center. This page is designed to help you quickly resolve common issues and get additional support if needed.

Frequently Asked Questions (FAQs)

Getting Started

What is Classiq?

Classiq is quantum-computing software that enables the design, optimization, analysis, and execution of quantum algorithms. Check out how to get started here.

I'm new to the platform—what are my first steps?

Start with Registration and Installation to get access to the platform.
The Onboarding Tutorial will help with your first steps in coding.
When you feel confident, try some of our real-world applications.

Can I execute algorithms on quantum computers using Classiq?

Yes! With Classiq, you can run quantum algorithms on the quantum computers you have access to. Check out our list of quantum providers.

Technical Questions

How can I fix __PROTECTED_0__?

This error arises when your authentication credentials are denied. Try overriding your authentication credentials by executing authenticate(overwrite=True).

My Studio cannot reconnect

If you’re experiencing failed attempts to reconnect to the Studio or long loading times, please try closing and reopening your web browser.

I'm having authentication problems in the Studio

Try authenticating again using:

import classiq

classiq.authenticate()

To prevent such problems in the future, it is a good practice to begin code files in the Studio with authenticate().

Example notebooks in the Studio aren’t working

Some example notebooks (e.g., chemistry) require additional packages in the Studio. First, try:

pip install "classiq[chemistry]"

If it still doesn’t work, reset the virtual environment by running:

reset-user-env

If none of these options work, reach out to us on the Community Slack.

How do I import a QASM file using the Python SDK?

Use quantum_program_from_qasm().

Contributing to the Library

How can I contribute to the Classiq Library?

You can find contribution guidelines on this page.

Designing Quantum Models

How do I define an observable?

In Classiq, you can define any observable as a linear combination of Pauli strings. To measure a set of observables from a quantum program, see Execution Session and the Execution Tutorial.

How can I transform a circuit with many gates into a shallower circuit using more qubits?

You can synthesize the quantum circuit using Constraints. See Quantum Program Constraints.

How do I target a hardware’s native gate set?

You can synthesize the quantum program using hardware-aware synthesis. See Hardware-Aware Synthesis.

How do I create a multi-control, multi-target gate?

Using control, you can define multi-qubit controls and gates. You can also use if_ for classical control of quantum gates. See Classical Control Flow.

How do I use controlled operations on multiple qubits instead of QArrays?

There are two ways to work around this: either bind the qubits you want to a QArray (see bind) or slice the QArrays (see Path Operators).

How do I apply a single-qubit gate to multiple qubits?

Use the apply_to_all function. See Utility functions.

How can I uncompute a qubit?

You can use the free() function. For more information, see Uncomputation.

How do I obtain the width and depth of my quantum program?

Use qprog.data.width and qprog.transpiled_circuit.depth.

Execution

How do I execute a quantum program on hardware?

Use ExecutionPreferences and set the backend appropriately. The Execution Tutorial shows this step by step.

How do I convert a combinatorial optimization problem into a problem Hamiltonian?

In Qmod, it is possible to use Pyomo to formulate the optimization problem. See Problem Formulation.

How can I change the number of shots when executing a quantum program?

Use ExecutionPreferences and set the number of shots. See the Execution Tutorial.

How do I run a VQA on IBM hardware using `ExecutionSession`?

After defining the quantum program, use ExecutionSession.minimize() or ExecutionSession.estimate() for VQAs. See Execution Tutorial 2: Expectation Values and Parameterized Quantum Programs.

Need More Help?

If your question is not answered here, please:

Reach out in the #support-and-questions channel on our community Slack.
For additional assistance, to report a bug, or to request a feature, submit a ticket via our Support Center.

​Support

​Frequently Asked Questions (FAQs)

​Getting Started

​Technical Questions

​Contributing to the Library

​Designing Quantum Models

​Execution

​Need More Help?