Job limits
When you send a job to an IBM® QPU, it is first sent to the job validation service. This service tries to ensure that the job will be able to run on the QPU so you don't have to wait for it to go through the queue and then have the job fail. These checks include enforcing the described limits.
Certain primitive options increase the circuit size. The described limits are checked after the expected increase in circuit size. In particular, these options increase circuit size:
- Dynamical decoupling and gate-folding ZNE introduce additional gates that are included in the instructions for the Maximum number of low-level instructions per qubit limit.
- Gate-folding ZNE introduces additional two-qubit gates relevant to the Maximum number of two-qubit gates per job limit. The number of two-qubit gates is multiplied by the sum of noise factors requested in gate-folding ZNE.
Maximum executions
At most, 10 million executions are allowed. The number of executions is the number of circuits times the number of shots, where the circuits are those generated after PUB elements are broadcasted.
For example, if you have a PUB with one circuit, observables with shape (1, 6), and parameters with shape (4, 1), this would render circuits (or fewer, if some observables commute). If you requested 2,000 shots, then the total number of executions is .
Maximum number of low-level instructions per qubit
The service permits up to 26.8 million control-system instructions per qubit. This ensures that the user circuits fit within the control system's instruction memory. The following table describes how the system translates instruction set architecture (ISA) circuit instructions to control system instructions when calculating this limit.
| Instruction | Count |
|---|---|
rz | 1 |
delay | 1 |
sx | 2 |
x | 2 |
cx | 5 |
cz | 5 |
ecr | 5 |
measure | 10 |
reset | 17 |
init | 50 |
This table captures the heuristic used in validation and does not reflect the exact number of instructions used to implement an operation.
Maximum number of single- and two-qubit gates per circuit
The maximum number of single-qubit gates are as follows:
- 30 million RZ gates
- 20 million SX gates
The maximum number of two-qubit gates per circuit is 5 million for static circuits and 100,000 for dynamic circuits. This ensures that the job can be manipulated within the memory limits of the low-level software stack.
Considerations and limitations for dynamic circuits
For considerations and limitations related to running dynamic circuits on quantum hardware, see the Hardware considerations and limitations for classical feedforward and control flow guide.