Breakdown of QPU Access Time¶
As illustrated in Figure 95, the time to execute a single QMI on a QPU, QPU access time, is broken into two parts: a one-time initialization step to program the QPU (blue) and typically multiple sampling times for the actual execution on the QPU (repeated multicolor).
The QPU access time also includes some overhead:
where \(T_P\) is the programming time, \(T_s\) is the sampling time, and \(\Delta\) (reported as qpu_access_overhead_time by SAPI) is an initialization time spent in low-level operations, roughly 1-2 ms for D-Wave 2000Q systems and 10-20 ms for Advantage systems.
The time for a single sample is further broken into anneal (the anneal proper; green), readout (read the sample from the QPU; red), and thermalization (wait for the QPU to regain its initial temperature; pink). Possible rounding errors mean that the sum of these times may not match the total sampling time reported.
where \(R\) is the number of reads, \(T_a\) the single-sample annealing time, \(T_r\) the single-sample readout time, and \(T_d\) the single-sample delay time, which consists of the following optional components:
|||See descriptions of these components under QPU parameters. The reinitialize_state is used only for reverse annealing.|