<figcaption><span class="captiontitle">RB error metrics</span> <span class="captiondetail">This table shows estimates for the error rate that would be obtained using two different Randomized Benchmarking (RB) protocols . The Clifford RB number corresponds to the most standard form of RB, Clifford RB (CRB), where random Clifford gate sequences are performed. This number is dependent on how the Clifford operations are compiled into the primitive gates, and so if you didn't specify a Clifford compilation and pygsti couldn't deduce one, this quantity will be absent. Note that this is the error rate per-Clifford; it has not been rescaled to a per-primitive error rate. The primitive RB number corresponds to performing RB on random sequences of the primitive gates, rather than the Cliffords, which is known as <q>Direct RB</q> (DRB). DRB allows for sampling layers of primitives according to a general probability distribution over the primitive gates; the number reported here corresponds to uniformly sampling the primitive gates. This number does not require any compilation table and is always be computed by pyGSTi. Two caveats regarding these RB numbers: 1) The primitive RB number is not meaningful for arbitrary gate sets; if the gate set generates the Clifford group or it is a universal gate set then it is definitely meaningful, modulo the second caveat. 2) These predicted RB numbers rely on a perturbative technique, and if the estimated gates are far from their ideal counterparts the predicted numbers may be very inaccurate (and the empirical RB error rate itself may even be ill-defined: the RB decay could be non-exponential). For both of these RB protocols there is also more than one definition of the RB number, as a function of the p obtained from fitting RB data to <span class="math">A + Bp^m</span>. Here we use the definition <span class="math">r = (4^n - 1)(1-p)/4^n</span> for an n-qubit gate set, which means that <span class="math">r</span> = entanglement infidelity = 1/2 diamond distance if there are uniform depolarizing errors on all the gates (where these two quantities are w.r.t. the gate set benchmarked, so the Clifford gates for CRB and the primitive gates for DRB). For more general errors, these first two quantities will often be roughly equal, although that is not guaranteed. Note that these numbers should not be directly compared to RB numbers derived using the commonly-used alternative formula <span class="math">r = (2^n - 1)(1-p)/2^n</span> (which is related to average gate infidelity, rather than entanglement infidelity).</span></figcaption>
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