• Open Access

Synthetic Topological Qubits in Conventional Bilayer Quantum Hall Systems

Maissam Barkeshli and Xiao-Liang Qi
Phys. Rev. X 4, 041035 – Published 20 November 2014

Abstract

The idea of topological quantum computation is to build powerful and robust quantum computers with certain macroscopic quantum states of matter called topologically ordered states. These systems have degenerate ground states that can be used as robust “topological qubits” to store and process quantum information. In this paper, we propose a new experimental setup that can realize topological qubits in a simple bilayer fractional quantum Hall system with proper electric gate configurations. Our proposal is accessible with current experimental techniques, involves well-established topological states, and, moreover, can realize a large class of topological qubits, generalizing the Majorana zero modes studied in recent literature to more computationally powerful possibilities. We propose three tunneling and interferometry experiments to detect the existence and nonlocal topological properties of the topological qubits.

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  • Received 6 August 2013

DOI:https://doi.org/10.1103/PhysRevX.4.041035

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Authors & Affiliations

Maissam Barkeshli1 and Xiao-Liang Qi2

  • 1Station Q, Microsoft Research, Santa Barbara, California 93106-6105, USA
  • 2Department of Physics, Stanford University, Stanford, California 94305, USA

Popular Summary

The goal of quantum computation is to harness the laws of quantum mechanics in order to store and process information in fundamentally more powerful ways than current, classical computers can. However, an intrinsic difficulty to building a quantum computer is that quantum states are so fragile that the smallest amounts of environmental noise can unravel their intricate patterns of entanglement. Topological quantum computation overcomes this problem by utilizing certain macroscopic quantum states of matter called topologically ordered states. These systems have degenerate ground states that are intrinsically robust to environmental perturbations, providing an ideal platform for quantum computation. We propose a new experimental setup that can realize topological qubits, which can be used to process and store quantum information.

Our setup consists of two layers of a two-dimensional electron system, each forming the most stable and well-studied fractional quantum Hall state that has already been realized since the early 1980s. By using proper electric gate configurations—top and bottom gates, which prompt interlayer tunneling based on electron backscattering—we show that one can effectively change the topology of the space to which the electrons are confined, ultimately giving rise to a topological qubit. We propose three experimental tests of the topological qubit: an interlayer fractional quantized Hall conductance, measurement of certain localized topological zero modes via a technique analogous to scanning tunneling microscopy, and an interferometry measurement to detect the nonlocal nature of the topological qubit.

These tests are accessible with current experimental techniques, involve well-established topological states, and moreover, can realize a large class of topological qubits, generalizing the current proposals to more computationally powerful possibilities.

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Vol. 4, Iss. 4 — October - December 2014

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It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 3.0 License. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

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