Gate fidelity comparison in semiconducting spin qubit implementations affected by control noises

Abstract

A comparison of gate fidelities between different spin qubit types defined in quantum dots and a donor under different control errors is reported. We studied five qubit types, namely the quantum dot spin qubit, the double quantum dot singlet-triplet qubit, the double quantum dot hybrid qubit, the donor qubit and the quantum dot spin-donor qubit. For each one, we derived analytical time sequences that realize single qubit rotations along the principal axis of the Bloch sphere. We estimated the effects of control errors on the gate fidelity by using a Gaussian noise model. Then we compared the gate fidelities among qubit implementations due to pulse timing errors by using a realistic set of values for the error parameters of control amplitudes. E Ferraro et al H J J J J J J J J . ( ) The sequence that realizes R z (θ) is composed by the product of three steps U t U t U t J J J J J J evolution operators are calculated starting from the Hamiltonians H E J J J z z z z i i 3 2 1 , 2 2 J J max max 1 2 1 4 -HQ J J J 1 2 1 4 1 2 -¢ + + ( ) J J 3 4 1 2 --( ) J J J E 2

On the robustness of the hybrid qubit computational gates through simulated randomized benchmarking protocols

“…In this Section the RB simulations for the hybrid qubit affected by a quasi-static Gaussian (QSG) noise are presented and analyzed. The hybrid qubit is an all-electrical qubit realized through confinement of three electrons in a double quantum dot 21 , 24 , 25 . The input controls to operate the qubit are two exchange couplings and between the pair of electrons belonging to different quantum dots.…”

“…The gate sequences, derived in Ref. 24 , 26 , provide for each gate operation the sequence of exchange interaction pulses to be applied to the qubit and the corresponding duration time. Our sequences have control signals and with abrupt (ideal) switching edges.…”

“…In this paper, the analytical gate sequences, derived in Ref. 24 , for rotations along and axis for the hybrid qubit are exploited to simulate RB protocols. Gates taken from the Clifford group are used and noise is included by assuming that each operation is allowed to have some error.…”

Bandwidth-Limited and Noisy Pulse Sequences for Single Qubit Operations in Semiconductor Spin Qubits

“…We present for each spin qubit the results related to the single qubit gate operation and starting from the initial condition . The rotations are obtained through analytical input sequences that are reported in Appendix A [ 18 ]. We point out that the method is general and valid for arbitrary rotation angles as well as any initial condition.…”

“…Table A1 contains the analytical gate sequences for all the spin qubit under study that realize in one or multiple steps the rotations and on the Bloch sphere [ 18 ].…”