Non-Abelian Anyon Braiding in Corbino Topological Josephson Junctions
Abstract
Approved for Public Release- Suppressing the decoherence of qubits becomes one of the most important technical challenges in quantum computing to achieve more efficient operation. To achieve this goal, it has been theoretically proposed to use robust quantum states that appear in topological superconductors (TSCs). One of these candidates is non-abelian anyons, often called Majorana bound state (MBS), which can occur in the defects, such as vortices, in topological superconductors. In this project, we propose to constructtopological superconductors by hybridizing 3-dimensional (3D) topological insulators (TIs) with conventional s-wave superconductors(sSCs) to construct TSCs in a 3DTI-sSC hybrid device. In particular, we will use a tri-Josephson junction (JJ) as a building block to locate the MBS at the junction of three sSCs. By combining tri-JJs, one can demonstrate the creation, fusion of a pair of MBS, and also transport the MBS to another junction by controlling the relative superconducting phase of the tri-JJ array by external magnetic fields. We plan to use the Corbino-JJ device, a device without an explicit edge, to demonstrate a unique topology to control thedynamics of MBSs for their manipulation and detection using the biasing supercurrent and applied magnetic field through the phase bias loops. In order to achieve the highest device quality, we will use exfoliated Sn-doped Bi1.1Sb0.9Te2S (Sn-BSTS) single crystal capped with a Te deposition layer prepared under UHV conditions to passivate the surface. Nb superconducting electrodes are used to form multi-terminal JJs on the surface of Sn-BSTS. Our preliminary data show that we can achieve unprecedented quality of JJs in thiscombination. To robustly demonstrate the non-Abelian statistics of Majorana fermions in 3D TI Josephson junctions, it is essential to create, braid, and fuse MBSs and minimize topologically trivial supercurrents. In particular, in a Corbino geometry Josephson junction with concentric circular contacts, MBSs bound to Josephson vortex cores appear at zero excitation energy. By adjusting the superconducting phase difference, these vortices can be moved, facilitating the exchange of MBSs. These tri-junctions nucleate a pair of vortices, each containing an MBS, when a phase shift occurs. By connecting the semi-annular outer SCs with a superconducting loop,the junction returns to a two-terminal configuration. As an external bias drives the phase shift, the MBSs move along the junction and some collide, leading to non-Abelian state evolution. Our device can be seen as a single device Corbino geometry adaptation of the Fu and Kane proposal, or as a variation of Majorana train concepts using Corbino geometry superconducting contacts. We also expect that the observation of fractional AC Josephson effects would clearly imply non-Abelian statistics of Majorana fermions. The device provides manipulation capabilities for non-Abelian anyons without the need for extensive dynamic control or additional setups. Advanced computing and communications are critical to future naval capabilities, with quantum technology at the forefront. TSC-based efficient quantum computers can solve problems beyond classical computers, providing applications such as data encryption and optimization for the Navy. Our goal is to bridge this gap and provide the Navy with powerful quantum tools for efficient computing and communications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 24, 2024
- Source ID
- N000142412081
Entities
People
- Philip Kim
Organizations
- Office of Naval Research
- President and Fellows of Harvard College
- United States Navy