Non-technical abstract: Quantum computing, which leverages quantum mechanical processes for information storage and manipulation, is expected to surpass classical computing schemes. Recently, prototypes of quantum computers have demonstrated computing power on tasks that are difficult or impossible to be carried out by a conventional computer. However, to achieve a full-scale quantum computer which can carry out universal computation tasks, the critical issue of quantum decoherence – a process that causes the loss of quantum information and the generation of errors, needs to be addressed first. One promising way to tackle this challenge is to utilize a kind of exotic quantum particles, known as Majorana fermions, that are indistinguishable from their antiparticles. Such unique property allows one to construct the basic element of quantum computing, i.e. a quantum bit or qubit, using a pair of coupled Majorana fermions, which can give rise to a new type of qubit that is naturally protected from decoherence. This project aims to integrate the needed elements to build prototypes of such qubit using new superconductor materials. The project emphasizes on the education and outreach program for graduate and undergraduate students, and K-12 students and schoolteachers, which are combined with the research endeavors to build a next generation quantum-literate workforce.
The project establishes the material and device foundation for building a topological qubit – the kind of qubit that is protected against decoherence. The research exploits new materials known as topological superconductors, which have superconducting energy gap in their interiors and harbor Majorana zero modes at their boundaries. The candidate materials are two-dimensional (2D) systems and heterostructures, in which superconductivity, magnetism and spin-orbit coupling co-exist, such as the surface state of (111)-oriented gold coupled to a superconductor and a magnetic insulator. Such materials feature a high degree of tunability and allow the control of Majorana zero modes by manipulating the properties of the superconductor materials themselves. At the same time, the focused materials are scalable, which allows them to be easily fabricated into the needed nano structures/devices by following standard fabrication procedures. The research follows the “measurement-based†scheme for quantum information processing, which utilizes the concept of quantum state teleportation through a pair of Majorana zero modes. The project aims to achieve several milestones towards achieving a topological qubit, which includes: 1. prove the quantum non-locality of a pair of coupled Majorana zero modes; 2. control Majorana zero modes using tunable superconductor materials; and 3. demonstrate interferometer devices for topological qubit. The success of the project offers a path towards understanding the novel quantum phases emerging in material heterostructures and will stimulate quantum information sciences. The outcome will advance both basic science and information technology, paving the way for the next generation computation.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
