Experimental review on Majorana zero-modes in hybrid nanowires

Fu, Ji-Bang; Li, Bin; Zhang, Xinfang; Yu, Guangzheng; Huang, Guang-Yao; Deng, Mingtang

doi:10.1007/s11433-021-1737-4

Cited by 11 publications

(3 citation statements)

References 178 publications

(180 reference statements)

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“…Two years later the first experimental indication using Fe chains constructed atom by atom on Pb(110) appeared in the paper by Nadj-Perge et al [27]. For other platforms next, we refer the readers to recent extensive reviews [38,39].…”

Section: Introductionmentioning

confidence: 99%

Sequencing one-dimensional Majorana materials for topological quantum computing

Minissale,

Bondavalli,

Figueira

et al. 2024

J. Phys. Mater.

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Majorana fermions are a fascinating class of particles with unique and intriguing properties: they are their own antiparticles, as first theorized by the Italian physicist Ettore Majorana in 1937. In recent decades, research in condensed matter physics shows theoretically that in certain exotic states of matter, such as topological superconductors, pairs of Majorana fermions can emerge as bound states at defects or interfaces, known as Majorana Zero Modes (MZMs). They behave like non-local anyons and could be used as decoherence-protected qubits. After the seminal work of Kitaev (2001), one-dimensional artificial setups have been developed in line with the concept of the Kitaev chain to implement MZMs. As no definite proof has yet been widely accepted by the community, improvements in the architectures and setups have been realized, and different platforms have been devised, which could be kinds of ‘DNA’ in this rapidly evolving vivid ecosystem. Here, we sequence these ‘DNAs’ and draw perspectives for topological quantum computation.

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Section: Introductionmentioning

confidence: 99%

Sequencing one-dimensional Majorana materials for topological quantum computing

Minissale,

Bondavalli,

Figueira

et al. 2024

J. Phys. Mater.

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“…Adding in a magnetic field enables this system to behave as an effective spinless p-wave topological superconductor, which allows for MZM states [6]. Recently, there have been new developments in material choices and experimental methods to identify MZMs in semiconductor nanowire-superconductor systems [7], designed to overcome challenges identified during the first wave of experiments [8][9][10]. These include trying new combinations of semiconductors and epitaxial superconductors, e.g.…”

Section: Introductionmentioning

confidence: 99%

First Principles Assessment of CdTe as a Tunnel Barrier at the $\mathbfα$-Sn/InSb Interface

Jardine¹,

Dardzinski²,

Yu³

et al. 2023

Preprint

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Majorana zero modes, with prospective applications in topological quantum computing, are expected to arise in superconductor/semiconductor interfaces, such as β-Sn and InSb. However, proximity to the superconductor may also adversely affect the semiconductor's local properties. A tunnel barrier inserted at the interface could resolve this issue. We assess the wide band gap semiconductor, CdTe, as a candidate material to mediate the coupling at the lattice-matched interface between α-Sn and InSb. To this end, we use density functional theory (DFT) with Hubbard U corrections, whose values are machine-learned via Bayesian optimization (BO) [npj Computational Materials 6, 180 (2020)]. The results of DFT+U(BO) are validated against angle resolved photoemission spectroscopy (ARPES) experiments for α-Sn and CdTe. For CdTe, the z-unfolding method [Advanced Quantum Technologies, 5, 2100033 (2022)] is used to resolve the contributions of different kz values to the ARPES. We then study the band offsets and the penetration depth of metal-induced gap states (MIGS) in bilayer interfaces of InSb/α-Sn, InSb/CdTe, and CdTe/α-Sn, as well as in tri-layer interfaces of InSb/CdTe/α-Sn with increasing thickness of CdTe. We find that 16 atomic layers (3.5 nm) of CdTe can serve as a tunnel barrier, effectively shielding the InSb from MIGS from the α-Sn. This may guide the choice of dimensions of the CdTe barrier to mediate the coupling in semiconductor-superconductor devices in future Majorana zero modes experiments.

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“…While experiments have directly observed the characteristic gapless edge states of topological insulators and topological metals, for example through Hall conductance measurements [8,16] or through photoemission spectroscopy techniques [17,18,21,22,23], experiments seeking the observation of Majorana edge states of topological superfluids have not yet achieved the same smoking-gun status [118,119]. We now survey the experimental prospects for realising topological superfluids on the basis of chiral p-wave pairing.…”

Section: Topological Materials: the Big Picturementioning

confidence: 99%

Microscopic Theory of Topological Superfluidity in 2D Fermi Gases

Thompson¹

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<p>The twodimensional chiral p-wave superfluid is known to be topological, with gapless Majorana states expected to exist at its edge. The possibility to utilise such Majorana excitations as fault-tolerant quantum bits has spurred interest in robust experimental realisation of such systems. One proposed pathway is to use spin-orbit coupled and spin-imbalanced ultracold gases of fermionic atoms subject to conventional s-wave pairing, as inducing a large-enough Zeeman energy splitting between pseudo-spin-1/2 states drives the system into a topological superfluid (TSF) phase with chiral-p-wave characteristics. In this thesis, we apply and extend advanced theoretical methods to study this topological phase transition in detail. Specifically, our work elucidates what happens when the s-wave interaction strength between atoms is increased so that the system undergoes the BCS-to-BEC crossover. While previous studies have largely focused on the weakly interacting BCS regime, studying the full crossover reveals new properties of the TSF phase that may aid its experimental realisation in the future. In particular, we obtain phase diagrams in the parameter space of the s-wave interaction strength and Zeeman energy. As long as the system is in the nontopological superfluid (NSF) phase, it shows the ordinary features expected during the BCS-to-BEC crossover, such as the shrinking and disappearance of the Fermi surfaces as the s-wave interaction strength is increased. The TSF phase, however, exhibits strikingly different behavior: it retains the BCS-limit characteristics of a TSF even as the s-wave interaction strength reaches extremely large values. The phase diagrams we obtain also show that increasing the s-wave interaction strength changes the nature of the topological transition from second-order continuous to first-order. During the first-order topological transition, the system splits into coexisting regions of NSF and TSF phases. We study this phase coexistence theoretically and obtain analytical formulae that capture the behaviour of all relevant thermodynamic quantities during the first-order topological transition. In that, our work extends current fundamental knowledge about spin-imbalanced Fermi gases to situations with finite spin-orbit coupling. We also investigate the gapless edge states emerging at the system’s boundaries, as these are crucial for experiments that aim to observe topological phases and realise novel quantum-information-processing architectures. The principle of bulk-boundary correspondence guarantees that gapless Majorana excitations should be localised to the interface between coexisting NSF and TSF regions. We develop a detailed theoretical description of this novel topological interface state and compare its physical features with those exhibited by the Majorana states expected to exist at the system’s boundary with vacuum.</p>

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Experimental review on Majorana zero-modes in hybrid nanowires

Cited by 11 publications

References 178 publications

Sequencing one-dimensional Majorana materials for topological quantum computing

Sequencing one-dimensional Majorana materials for topological quantum computing

First Principles Assessment of CdTe as a Tunnel Barrier at the $\mathbfα$-Sn/InSb Interface

Microscopic Theory of Topological Superfluidity in 2D Fermi Gases

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