Just-in-time Quantum Circuit Transpilation Reduces Noise
Running quantum programs is fraught with challenges on on today's noisy
intermediate scale quantum (NISQ) devices. Many of these challenges originate
from the error characteristics that stem from rapid decoherence and noise
during measurement, qubit connections, crosstalk, the qubits themselves, and
transformations of qubit state via gates. Not only are qubits not "created
equal", but their noise level also changes over time. IBM is said to calibrate
their quantum systems once per day and reports noise levels (errors) at the
time of such calibration. This information is subsequently used to map circuits
to higher quality qubits and connections up to the next calibration point.
  This work provides evidence that there is room for improvement over this
daily calibration cycle. It contributes a technique to measure noise levels
(errors) related to qubits immediately before executing one or more sensitive
circuits and shows that just-in-time noise measurements benefit late physical
qubit mappings. With this just-in-time recalibrated transpilation, the fidelity
of results is improved over IBM's default mappings, which only uses their daily
calibrations. The framework assess two major sources of noise, namely readout
errors (measurement errors) and two-qubit gate/connection errors. Experiments
indicate that the accuracy of circuit results improves by 3-304% on average and
up to 400% with on-the-fly circuit mappings based on error measurements just
prior to application execution.
Ellis Wilson Sudhakar Singh Frank Mueller