02685nas a2200205 4500008004100000245006300041210006100104260001500165300001100180490000700191520207900198100002102277700001802298700002202316700001602338700001902354700001802373700001902391856006902410 2018 eng d00aHigh-fidelity quantum gates in Si/SiGe double quantum dots0 aHighfidelity quantum gates in SiSiGe double quantum dots c2018/02/15 a0854210 v973 a

Motivated by recent experiments of Zajac et al. [Science 359, 439 (2018)], we theoretically describe high-fidelity two-qubit gates using the exchange interaction between the spins in neighboring quantum dots subject to a magnetic field gradient. We use a combination of analytical calculations and numerical simulations to provide the optimal pulse sequences and parameter settings for the gate operation. We present a synchronization method which avoids detrimental spin flips during the gate operation and provide details about phase mismatches accumulated during the two-qubit gates which occur due to residual exchange interaction, nonadiabatic pulses, and off-resonant driving. By adjusting the gate times, synchronizing the resonant and off-resonant transitions, and compensating these phase mismatches by phase control, the overall gate fidelity can be increased significantly.

1 aRuss, Maximilian1 aZajac, D., M.1 aSigillito, A., J.1 aBorjans, F.1 aTaylor, J., M.1 aPetta, J., R.1 aBurkard, Guido uhttps://journals.aps.org/prb/abstract/10.1103/PhysRevB.97.085421