FAQ

Does VTT QX provide pulse-level access?

Currently, we only provide circuit-level access. If you wish to execute pulses on VTT quantum computers please contact support.

Is there a queue?

Submitting jobs to VTT QX devices places jobs in a per device first-in-first-out queue to be scheduled for execution.

What are the device circuit size limitations?

You can view the per device limitations in the device card. This is set to avoid unreasonably long queuing times for a single user.

Is there any optimization applied during gate-to-pulse compilation?

No circuit optimization is performed after the circuit has been submitted in serialized form with the IQM client. The gate-to-pulse compiler replaces each gate by the corresponding pulse and submits the pulses to the backend for execution.

Is heralding enabled on VTT quantum computers?

Heralding is an optional feature that allows for post-selection of shots, to filter out runs where one or more qubits were not in the ground state at the beginning of the circuit execution. This feature is available in VTT quantum computers but it is not officially supported by IQM and your mileage may vary.

What is the expected time-to-execution after a job has been scheduled on VTT Quantum computers?

An overhead of 10 seconds can be expected for VTT Q5. The largest overhead is introduced by compiling the pulses to instructions for the control electronics and the upload to the instruments.

Does the number of shots affect the calibration of VTT quantum computers?

No, a large number of shots will not cause thermal excitations of the qubits.

I am getting error “413 Request Entity Too Large” when submitting circuits

This may indicate that the request size you have submitted is too large to be allowed through VTT QX. This is currently set to 200MB, which is reflective of the current circuit size limitations on VTT QX devices (See below). If you are getting this error below the circuit size limitations please contact support.

Can I use Pennylane on VTT Quantum Computers?

Yes, however there is no official adapter. Instead one can use pennylane-qiskit plugin. Some modifications may be necessary.

Are there any limitations when using the VTT Quantum Computers?

There are a number of limitations that need to be taken into account when writing quantum circuits.

Batch size

On both Q5 and Q50 system, quantum circuits within a batch are processed sequentially. To prevent extensive queue occupation by large batches, we have set a maximum limit of 200 circuits per batch. Jobs submitting batches with more than 200 circuits will be rejected and the IQM client will return the following error

ClientConfigurationError: Client configuration error: {"error":"Request contains x circuits in batch which is larger than maximum number of circuits (200) allowed per batch for device <device-name>."}

Here, ‘X’ denotes the actual number of circuits attempted to be included in the batch.

Number of shots

The execution time for a quantum circuit scales with the number of shots. To avoid disproportionately long job durations, we impose a threshold of 100,000 shots per circuit. Should your experiment require more shots, we recommend dividing it into multiple separate jobs. For cases where this shot limit proves inadequate, please do not hesitate to reach out to our support.