Probing helicity and the topological origins of helicity via non-local Hanbury-Brown and Twiss correlations

Abstract

Quantum Hall edge modes are chiral while quantum spin Hall edge modes are helical. However, unlike chiral edge modes which always occur in topological systems, quasi-helical edge modes may arise in a trivial insulator too. These trivial quasi-helical edge modes are not topologically protected and therefore need to be distinguished from helical edge modes arising due to topological reasons. Earlier conductance measurements were used to identify these helical states, in this work we report on the advantage of using the non local shot noise as a probe for the helical nature of these states as also their topological or otherwise origin and compare them with chiral quantum Hall states. We see that in similar set-ups affected by same degree of disorder and inelastic scattering, non local shot noise "HBT" correlations can be positive for helical edge modes but are always negative for the chiral quantum Hall edge modes. Further, while trivial quasi-helical edge modes exhibit negative non-local "HBT" charge correlations, topological helical edge modes can show positive non-local "HBT" charge correlation. We also study the non-local spin correlations and Fano factor for clues as regards both the distinction between chirality/helicity as well as the topological/trivial dichotomy for helical edge modes.

22 pages, 10 figures, accepted for publication in Scientific Reports (2017)

References in corpus (16)

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• Shot noise in the edge states of 2D topological insulators
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Cited by in corpus (16)

• Quantum Transport in Topological Semimetals under Magnetic Fields
• Quantum Transport in Topological Semimetals under Magnetic Fields (II)
• Thermoelectric performance of topological boundary modes
• Nonlocal thermoelectric engines in hybrid topological Josephson junctions
• Unrestricted electron bunching at the helical edge
• Noise insights into electronic transport
• Forbidden Backscattering and Resistance Dip in the Quantum Limit as a Signature for Topological Insulators
• Finite frequency backscattering current noise at a helical edge
• Finite temperature quantum noise correlations as a probe for topological helical edge modes
• Reaching Van den Broeck limit in linear response and Whitney limit in nonlinear response in edge mode quantum thermoelectrics and refrigeration
• Unidirectional magneto-transport of linearly dispersing topological edge states
• Are thermal fluctuations the sole reason for finite longitudinal resistance in quantum anomalous Hall experiments?
• On the accuracy of conductance quantization in spin-Hall insulators
• Colored ${\Delta }_T$ noise probes the topological character of edge modes
• Disordered contacts can localize chiral edge electrons
• Disordered contacts can localize helical edge electrons