Electronically-controlled one- and two-qubit gates for transmon quasicharge qubits

• URL: http://arxiv.org/abs/2510.20127v1
• Date: Thu, 23 Oct 2025 02:06:39 GMT
• Title: Electronically-controlled one- and two-qubit gates for transmon quasicharge qubits
• Authors: Nicholas M. Christopher, Deniz E. Stiegemann, Abhijeet Alase, Thomas M. Stace,
• Abstract summary: We show that an electronically-controllable tunnel junction can be used to implement single- and two-qubit gates on quasicharge qubits.<n>Our results point to a compelling strategy for implementation of quasicharge qubit gates based on junctions of minimal Kitaev chains of quantum dots.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Superconducting protected qubits aim to achieve sufficiently low error rates so as to allow realization of error-corrected, utility-scale quantum computers. A recent proposal encodes a protected qubit in the quasicharge degree of freedom of the conventional transmon device, here referred to as the `quasicharge qubit'. Operating such a protected qubit requires implementing new strategies. Here we show that an electronically-controllable tunnel junction formed by two topological superconductors can be used to implement single- and two-qubit gates on quasicharge qubits. Schemes for both these gates are based on dynamical $4\pi$-periodic Josephson effect and therefore have gate speeds of the same order. The simulation of the dynamics of a topological Josephson junction in a parameter regime with non-negligible charging energy is the key novelty of this work. We also characterize the robustness of such gate operations against charge noise using Fermi's golden rule. Our results point to a compelling strategy for implementation of quasicharge qubit gates based on junctions of minimal Kitaev chains of quantum dots.

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