A collaborative research team led by Prof. Junwei Liu, Associate Professor within the Department of Physics on the Hong Kong University of Science and Technology (HKUST), and Prof Jinfeng Jia and Prof Yaoyi Li from Shanghai Jiao Tong University (SJTU), has identified the world’s first multiple Majorana zero modes (MZMs) in a single vortex of the superconducting topological crystalline insulator SnTe and exploited crystal symmetry to manage the coupling between the MZMs. This discovery offers a brand new pathway to realizing fault-tolerant quantum computers, which is published in Nature.
MZM is a zero-energy topologically nontrivial quasiparticle in a superconductor obeys non-Abelian statistics, allowing for inequivalent braiding sequences, although the overall variety of exchanges is similar. This contrasts with atypical particles, equivalent to electrons or photons, where different braiding all the time ends in the identical final state. This unique property protects MZMs from local perturbations, making them a perfect platform for robust fault-tolerant quantum computation. Although significant progress has been made in engineering artificial topological superconductors, the braiding and manipulation of MZMs remain extremely difficult resulting from their separation in real space, which complicates the vital movements for hybridization.
The newly published work collaborated by the theoretical group at HKUST and experimental group at SJTU, took a very different approach by benefiting from the unique feature of crystal-symmetry-protected MZMs to eliminate these bottlenecks. They demonstrated for the primary time the existence and hybridization of magnetic-mirror-symmetry-protected multiple MZMs in a single vortex of the superconducting topological crystalline insulator SnTe, using controlled methods that don’t require real space movement or strong magnetic fields, leveraging their extensive experience in low-temperature scanning tunneling microscopy, high-quality sample growth, and large-scale theoretical simulations.
The experimental group at SJTU observed significant changes within the zero-bias peak, a robust indicator of MZMs, within the SnTe/Pb heterostructure under tilted magnetic fields (Fig 4a-b). The HKUST theoretical team subsequently performed extensive numerical simulations to unambiguously show that the anisotropic responses to tilted magnetic fields indeed originate from crystal-symmetry-protected MZMs. By utilizing the kernel polynomial method, they successfully simulated large vortex systems with lots of of tens of millions of orbitals, enabling further exploration of novel properties in vortex systems beyond just crystal-symmetry-protected MZMs. The research opens a brand new frontier for detection and manipulation of crystal-symmetry-protected multiple MZMs. Their findings pave the best way for the experimental demonstration of non-Abelian statistics, and the development of latest sorts of topological qubits and quantum gates based on crystal-symmetry-protected multiple MZMs.
*Note: Prof. Junwei Liu from HKUST, Prof. Yaoyi Li from SJTU, and Prof. Jinfeng Jia from SJTU are the corresponding authors. Chun Yu Wan from HKUST, Dr. Tengteng Liu from SJTU and Dr. Hao Yang from SJTU are the co-first authors.
