Fig. 1
From: Experimental quantum verification in the presence of temporally correlated noise
QCVV sequence construction and mapping to accumulated error. a Overview of unitary sequence construction for RB and GST, using Clifford gates, C l or fiducial operations, Fα,β and repeated germs (G)n respectively. b Schematic representation of slowly and rapidly varying noise with relevant time scales defined by the sequence where δ represents the instantaneous noise values drawn from a normal distribution with σ2 variance. Grey lines are other possible noise realisations. For RB, the noise is sampled from this distribution and varies shot-to-shot between noise realisations, while in GST a single value is selected for the entire set of experiments. c Sequence-dependent “random walk” calculated for an arbitrary QCVV sequence (here according to the RB prescription) with J = 100 in Pauli space. Green dot indicates origin and black triangle indicates sequence terminus. Blue line represents the 3D walk, which can be used to calculate the trace infidelity while the grey line represents the 2D projection, measurable in a standard projective measurement. The green arrow indicates the net walk vector, \({\vec{\boldsymbol V}}_{2D}\), given unit step size
