QMI Timing Overview¶
Fig. 62 shows a simplified diagram of the sequence of steps, the dark red set of arrows, to execute a quantum machine instruction (QMI) on a D-Wave system, starting and ending on a user’s client system. Each QMI consists of a single input together with parameters. A QMI is sent across a network to the SAPI server and joins a queue. Each queued QMI is assigned to one of possibly multiple workers, which may run in parallel. A worker prepares the QMI for the quantum processing unit (QPU) and optionally for postprocessing, sends the QMI to the QPU queue, receives samples (results) and optionally post-processes them (overlapping in time with QPU execution), and bundles the samples with additional QMI-execution information for return to the client system.
|||Postprocessing for D-Wave 2000Q and earlier systems includes optimization and sampling algorithms; on Advantage systems, postprocessing is limited to computing the energies of returned samples. Ocean software provides postprocessing tools, you can use these for Advantage systems.|
The total time for a QMI to pass through the D-Wave system is the service time. The execution time for a QMI as observed by a client includes service time and internet latency. The QPU executes one QMI at a time, during which the QPU is unavailable to any other QMI. This execution time is known as the QMI’s QPU access time.
Users executing on a D-Wave system are charged for QPU access time.
For customers purchasing time from D-Wave, this will be a financial charge. For users on a customer-owned system, this will typically be an administrative charge.