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arXiv:1706.09967 · Physical review. B./Physical review. B

Long-range entanglement for spin qubits via quantum Hall edge modes

Samuel J. Elman, Stephen D. Bartlett, Andrew C. Doherty

Published Sep 5, 2017• 26 citations
arXivHTMLPDF

Abstract

We propose and analyze a scheme for performing a long-range entangling gate for qubits encoded in electron spins trapped in semiconductor quantum dots. Our coupling makes use of an electrostatic interaction between the state-dependent charge configurations of a singlet-triplet qubit and the edge modes of a quantum Hall droplet. We show that distant singlet-triplet qubits can be selectively coupled, with gate times that can be much shorter than qubit dephasing times and faster than decoherence due to coupling to the edge modes. Based on parameters from recent experiments, we argue that fidelities above $99%$ could in principle be achieved for a two-qubit entangling gate taking as little as 20 ns.

DOI
10.1103/physrevb.96.115407

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We analyze and give estimates for the long-distance coupling via floating metallic gates between different types of spin qubits in quantum dots made of different commonly used materials. In particular, we consider the hybrid, the singlet-triplet, and the spin-12\frac{1}{2}21​ qubits, and the pairwise coupling between each type of these qubits with another hybrid qubit in GaAs, InAs, Si, and Si0.9Ge0.1{\mathrm{Si}}_{0.9}{\mathrm{Ge}}_{0.1}Si0.9​Ge0.1​. We show that hybrid qubits can be capacitively coupled strongly enough to implement two-qubit gates, as long as the distance of the dots from the metallic gates is small enough. Thus, hybrid qubits are good candidates for scalable implementations of quantum computing in semiconducting nanostructures.