Experimental Demonstration of a Non-Quantized Square-Root Topological Insulator using Photonic Aharonov-Bohm Cages

Abstract Topological Thouless pumping and Aharonov–Bohm effect are both fundamental effects enabled by the topological properties of the system. Here, we study both effects together: topological pumping of interacting particles through Aharonov–Bohm rings. This system can prepare highly entangled many-particle states, transport them via topological pumping and interfere with them, revealing a fractional flux quantum. The type of the generated state is revealed by non-trivial Aharonov–Bohm interference patterns that could be used for quantum sensing. The reflections induced by the interference result from transitions between topological bands. Specific bands allow transport with a band gap scaling as the square-root of the particle number. Our system paves a new way for a combined system of state preparation and topological protected transport.

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The Aharonov-Bohm oscillation in the BiSbTe3 topological insulator macroflake

Applied Physics Letters ◽

10.1063/1.5023812 ◽

2018 ◽

Vol 112 (20) ◽

pp. 203103 ◽

Cited By ~ 3

Author(s):

Shiu-Ming Huang ◽

Pin-Chun Wang ◽

Chien Lin ◽

Sheng-Yu You ◽

Wei-Cheng Lin ◽

...

Keyword(s):

Topological Insulator ◽

Aharonov Bohm

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Coherent spin transport through helical edge states of topological insulator

npj Computational Materials ◽

10.1038/s41524-020-00442-z ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

R. A. Niyazov ◽

D. N. Aristov ◽

V. Yu. Kachorovskii

Keyword(s):

Magnetic Field ◽

High Temperature ◽

Topological Insulator ◽

Spin Transport ◽

Magnetic Impurity ◽

Quantum Calculations ◽

Edge States ◽

Level Spacing ◽

Aharonov Bohm ◽

Coherent Spin

AbstractWe study coherent spin transport through helical edge states of topological insulator tunnel-coupled to metallic leads. We demonstrate that unpolarized incoming electron beam acquires finite polarization after transmission through such a setup provided that edges contain at least one magnetic impurity. The finite polarization appears even in the fully classical regime and is therefore robust to dephasing. There is also a quantum magnetic field-tunable contribution to the polarization, which shows sharp identical Aharonov-Bohm resonances as a function of magnetic flux—with the period hc/2e—and survives at relatively high temperature. We demonstrate that this tunneling interferometer can be described in terms of ensemble of flux-tunable qubits giving equal contributions to conductance and spin polarization. The number of active qubits participating in the charge and spin transport is given by the ratio of the temperature and the level spacing. The interferometer can effectively operate at high temperature and can be used for quantum calculations. In particular, the ensemble of qubits can be described by a single Hadamard operator. The obtained results open wide avenue for applications in the area of quantum computing.

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Nanomechanical characterization of quantum interference in a topological insulator nanowire

Nature Communications ◽

10.1038/s41467-019-12560-4 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 5

Author(s):

Minjin Kim ◽

Jihwan Kim ◽

Yasen Hou ◽

Dong Yu ◽

Yong-Joo Doh ◽

...

Keyword(s):

Resonant Frequency ◽

Topological Insulator ◽

Quantum Interference ◽

Mechanical Vibration ◽

Surface States ◽

Impurity Scattering ◽

Dirac Fermion ◽

One Dimensional ◽

Aharonov Bohm

Abstract Aharonov–Bohm conductance oscillations emerge as a result of gapless surface states in topological insulator nanowires. This quantum interference accompanies a change in the number of transverse one-dimensional modes in transport, and the density of states of such nanowires is also expected to show Aharonov–Bohm oscillations. Here, we demonstrate a novel characterization of topological phase in Bi2Se3 nanowire via nanomechanical resonance measurements. The nanowire is configured as an electromechanical resonator such that its mechanical vibration is associated with its quantum capacitance. In this way, the number of one-dimensional transverse modes is reflected in the resonant frequency, thereby revealing Aharonov–Bohm oscillations. Simultaneous measurements of DC conductance and mechanical resonant frequency shifts show the expected oscillations, and our model based on the gapless Dirac fermion with impurity scattering explains the observed quantum oscillations successfully. Our results suggest that the nanomechanical technique would be applicable to a variety of Dirac materials.

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