Design and Dynamics of High-Fidelity Two-Qubit Gates with Electrons on Helium

Abstract: Systems of individual electrons electrostatically trapped on condensed noble gas surfaces have recently attracted considerable interest as potential platforms for quantum computing. The electrons form the qubits of the system, and the purity of the noble gas surface protects the relevant quantum properties of each electron. Previous work has indicated that manipulation of a confining double-well potential for electrons on superfluid helium can generate entanglement suitable for two-qubit gate operations. In this work, we incorporate a time-dependent tuning of the potential shape to further explore operation of two-qubit gates with the superfluid helium system. Through numerical time evolution, we show that fast, high-fidelity two-qubit gates can be achieved. In particular, we simulate operation of the \sqiswap and CZ gates and obtain fidelities of 0.999 and 0.996 with execution times of 2.9~ns and 9.4~ns, respectively. Furthermore, we examine the stability of these gate fidelities under non-ideal execution conditions, which reveals new properties to consider in the device design. With the insights gained from this work, we believe that an experimental realization of two-qubit gates using electrons on helium is feasible.