H-Series Workflow¶
User Authentication¶
Once a user’s email address has been set up with an account on Quantinuum Systems, an invitation email will be sent with a unique signup link to the Nexus User Portal. Once registration is completed, users will need to log into the user portal to view and accept our terms and conditions before they can fully access Quantinuum systems. Usage of qnexus requires the end user to authenticate with user credentials.
Note
See below for legacy access to the Quantinuum user portal.
Once a user’s email address has been set up with an account on Quantinuum Systems, an invitation email will be sent with a unique signup link to the Quantinuum User Portal. To complete registration, users will need to choose how they would like to sign in: either by creating a Quantinuum account or by using third party credentials. Currently Microsoft accounts are the only third party accounts supported. Usage of QuantinuumBackend requires the end user to enter their username and password for each python session.
Queue¶
When jobs are submitted, they are placed initially into the Nexus First-in-First-out queue, and then, subsequently into Quantinuum’s fair queue. Jobs will wait in the queue until they run on the target device. The fair queue is used to ensure each organization’s queue is represented, as per the terms of their contract, for machine access. The jobs submitted by users in the same organization are executed first by user group priority, then by the user priority, and then by submission order. If user and group priorities are all equal, the oldest job in the queue is always selected first. If users submit a job to a specific machine that is not available, the jobs will hold their position in the organization’s queue until that machine is available. Machines do not need to be online when submitting jobs.
Users are encouraged to submit jobs at their convenience. The H-Series quantum computers are periodically taken down for upgrades. If a job is submitted while the machine is in an upgrade cycle, it will remain in the queue and run when the machine is back online.
Compilation¶
Circuits can be submitted to Nexus for remote compilation to a circuit that satisfies the gateset predicate required by H-Series hardware, emulators and syntax checkers. This enables circuits to be automatically optimized for H-Series systems and run more efficiently. The default compilation setting is optimization level 2. If users desire to use a different optimization level, to turn all optimizations off, or to explore what optimization passes in TKET will do before submitting, examples of how to do this can be found in the Getting Started section.
Note
See below for legacy tools.
pytket-quantinuum documentation also provides information on compilation passes. pytket-quantinuum only enables local compilation. New users should transition to using nexus.
Job Batching¶
Quantinuum systems support the ability to run job batches. The batch feature gives users the ability to create “ad-hoc” reservations. Circuits submitted together in a batch will run at one time. The benefit to users is that once a batch hits the front of the queue, jobs in a batch will run uninterrupted until they are completed.
Once a batch is submitted, jobs can continue to be added to the batch, ending either when the user signifies the end of a batch or after 1 minute of inactivity.
Batches cannot exceed the maximum limit of 2,000 HQCs total. If the total HQCs for jobs in a batch hit this limit or a smaller limit set by the user, those jobs will not be cancelled. Instead, they will continue to run as regular jobs in the queue instead of as a batch.
Currently only the quantum computer and emulator targets support the batching feature. Batching is not supported on the syntax checkers.
Availability¶
The syntax checkers and emulators are nominally available 24 hours/day to subscribers via queued access. The syntax checkers are free to use while the emulators and quantum computers require HQCs.
Quantum computers are available periodically throughout a calendar month. The calendar of system availability is maintained on the user portal. If needed, users can check a device’s status by first consulting the calendar on the user portal. This provides day-by-day scheduling of machine availability. Calendars are frequently updated to reflect best available information. In addition, calendars can be checked directly with the pytket-quantinuum interface. The quantum computer might be available at different times on scheduled days, depending on device startup, calibration and maintenance tasks.
To ensure the highest performance of our systems, we periodically schedule and perform upgrades on the machines and their components. The machines are taken offline to perform the upgrades and conduct verification and validation tests to ensure consistent performance. The performance upgrades are then made available to our users. Typical improvements include upgrades to compute speed, number of available qubits, noise reduction, and overall system reliability.
Tracking Usage¶
Running a job on H-Series hardware requires H-System Quantum Credits (HQCs). When a circuit is submitted to a syntax checker, emulator, or quantum computer, the cost in HQCs is returned with the results. Submitting to a syntax checker does not cost HQCs, but the cost of submitting the job on a quantum computer will be returned with the result for planning purposes. The same equation is used for hardware and emulators, but the HQCs are allocated and tracked separately. You can check your credit balance in the user portal. An H-System Quantum Credit (HQC) is defined as,
\(HQC = 5 + \frac{N_{1q} + 10 N_{2q} + 5 N_m}{5000} * C\),
where \(N_{1q}\) is the number of 1-qubit gates, \(N_{2q}\) is the number of native 2-qubit gates, \(N_m\) is the number of state preparation and measurement operations in a circuit, including the initial implicit state preparation and any intermediate and final measurements and state resets, and \(C\) is the shot count.
Note
Nexus-hosted H-Series emulators (suffix Emulator or LE) do not require HQCs, but instead have a quota based on CPU usage in seconds. (link).
Job Status¶
qnexus documentation details how users can check compile and execute job status for all H-Series targets (link). The status is also available on the nexus user portal.
Note
The pytket-quantinuum documentation details how users can check job status using QuantinuumBackend. Users may set notification preferences via the user portal to allow email or text notifications related to job status.
Data Retention¶
Data from jobs are retained in the nexus user portal indefinitely. The data retention window is the same across all targets: quantum computers, emulators, and syntax checkers. To prevent unintentional loss of data, the recommended best practice is to retrieve and save job data as soon as jobs are completed.
Note
Data from jobs submitted are kept on the legacy quantinuum user portal for 40 days.
Upgrades¶
Quantinuum will issue Product Change Notifications (PCNs) to customers coincidental to when new upgrades will be made commercially available or prior to any significant system changes. PCNs will initially be emailed to active administrators and will be stored on the user portal for easy reference. All PCNs are available here to view.