Chiral Majorana edge state in a quantum anomalous Hall insulator-superconductor structure (1606.05712v1)

Abstract: After the recognition of the possibility to implement Majorana fermions using the building blocks of solid-state matters, the detection of this peculiar particle has been an intense focus of research. Here we experimentally demonstrate a collection of Majorana fermions living in a one-dimensional transport channel at the boundary of a superconducting quantum anomalous Hall insulator thin film. A series of topological phase changes are controlled by the reversal of the magnetization, where a half-integer quantized conductance plateau (0.5e2/h) is observed as a clear signature of the Majorana phase. This transport signature can be well repeated during many magnetic reversal sweeps, and can be tracked at different temperatures, providing a promising evidence of the chiral Majorana edge modes in the system.

• The paper establishes chiral Majorana edge states by detecting a half-integer (0.5e²/h) conductance plateau during magnetization reversal.
• The study employs QAHI-superconductor heterostructures to create one-dimensional transport channels consistent with theoretical predictions.
• The findings advance topological quantum computing by providing robust experimental insights into chiral topological superconductivity.

Analysis of Chiral Majorana Edge State in a Quantum Anomalous Hall Insulator-Superconductor Structure

This paper presents a thorough experimental paper on the detection of chiral Majorana edge modes (CMEMs) in a quantum anomalous Hall insulator (QAHI)-superconductor structure. The research demonstrates the existence of one-dimensional transport channels that host Majorana fermions at the boundaries of such topological states. This paper significantly contributes to the search for higher-dimensional Majorana states, which promises more robust representations of Ettore Majorana's original theoretical propositions.

Key Experimental Findings

The observed half-integer conductance plateau of 0.5e²/h during magnetization reversal serves as an experimental signature for identifying a single CMEM. This signature was consistently recorded during various magnetic field sweeps and within specified temperature ranges, which marks a clear departure from the "zero-bias conductance anomalies" typically indicative of zero-dimensional Majorana bound states. The interplay between superconductors and topological insulators, devoid of strong external magnetic fields, creates an environment conducive to the observation of chiral topological superconductivity. The device structure and experimental setup successfully demonstrate quantization phenomena consistent with the theoretical prediction of chiral Majorana transport channels.

Theoretical Implications

This work advances the understanding of topological phase transitions involving chiral topological superconductors (TSCs) described by odd-integer Chern numbers. This contributes fundamental insights into the non-Abelian statistics of Majoranas, which are crucial for their potential application in fault-tolerant quantum computing. The paper adeptly addresses the challenge of realizing Majorana states that more accurately reflect their theoretical characteristics, thus distinguishing these phenomena from trivial zero-dimensional states influenced by effects such as Kondo correlations and Andreev bound states.

Practical Implications and Future Directions

By constructing and experimentally validating a QAHI-superconductor system to exhibit chiral TSC behavior, this research provides a prototype for further exploration in quantum information science. Given the quantized nature of the CMEMs presented here, significant practical inroads are made toward manipulating Majorana fermions in solid-state devices for robust quantum computation applications.

Future research can capitalize on these findings by exploring more complex configurations and material systems that manipulate the phase and dynamics of Majorana states. Further sophistication in device design and material hybridization could enhance control over Majorana modes, fostering advances in quantum circuit design and integration.

In conclusion, this paper intricately bridges experimental observations with theoretical constructs to confirm the presence of chiral Majorana edge states. With strong experimental evidence and a deep theoretical foundation, this work paves the way for further inquiries into leveraging topological quantum states for computational advancements.