Majorana particles in topological insulator quantum wires

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Non-technical: This award from the Condensed Matter Physics program of the Division of Materials Research supports Purdue University with a research project which aims to create and manipulate exotic particles known as Majorana particles. Majorana particles are an important class of fundamental particles originally proposed in particle physics (such as in the study of neutrinos) as having the unique property of being their own anti-particle but have not been conclusively found despite decades of research. Recently, it has been realized that it is possible to create analogues of such elusive particles using realistic material systems. Besides their fundamental interests, such "condensed matter" analogues of Majorana particles could potentially be used as quantum "bits" (qubits) to build a robust quantum computer, which would revolutionize our ability to perform computation and solve many complicated problems with dramatically increased speed and reduced energy cost. This project aims to create and manipulate Majorana particles using nanowires of a novel type of insulator, "topological insulators", interfaced with superconductors. Such "topological superconductor nanowires" promise to offer a robust experimental material system to realize the Majorana particles and to manipulate them for possible future applications in quantum computing. The project will also enhance collaborations across multiple disciplines in physics and engineering, with other institutions and international partners. Several graduate and undergraduate students, from both physics and engineering, including those from underrepresented groups, are expected to actively participate and be trained. Outreach activities will also involve high school and undergraduate college students and teachers.Technical: Realizing and manipulating analogues of "Majorana particles" (MPs, originally proposed in a particle physics context) in condensed matter systems has attracted strong attention for both fundamental interests and for potential applications to enable fault-tolerant topological quantum computing (TQC). This project aims to realize and detect MPs in "topological superconducting quantum wires" consisting of topological insulator nanoribbons (TINR) coupled to s-wave superconductors, with supercurrent carried by a unique 1D spin-helical mode. Recent theories have suggested that such a setup has several important advantages and is among the most promising experimental systems to host MPs. The properties of MP will be investigated by tunneling spectroscopy, and dc and ac Josephson effects. The proposed research could establish a new, robust experimental platform to realize MP, to explore their novel physics and topological phase transitions, and pave the way for their applications in TQC. The project will also enhance collaborations across multiple disciplines in physics and engineering, with other institutions and international partners. Several graduate and undergraduate students, from both physics and engineering, including those from underrepresented groups, are expected to actively participate and be trained. Outreach activities will also involve high school and undergraduate college students and teachers.