Quantum strain sensor with a topological insulator HgTe quantum dot

Korkusiński, Marek; Hawrylak, Paweł

doi:10.1038/srep04903

Cited by 15 publications

(35 citation statements)

References 31 publications

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“…Following these pioneering works, a few other TI proposals [5][6][7][8][9][10][11] have been put forward with some experimental support [12,13]. More recently, topological QDs with cylindrical confinement have been investigated [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Their spectra feature discrete helical edge states protected against non-magnetic scattering and showing spinangular-momentum locking.…”

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confidence: 99%

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Blurring the Boundaries Between Topological and Nontopological Phenomena in Dots

2018

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We investigate the electronic and transport properties of topological and non-topological InAs0.85Bi0.15 quantum dots (QDs) described by a ∼ 30 meV gapped Bernevig-Hughes-Zhang (BHZ) model with cylindrical confinement, i.e., "BHZ dots". Via modified Bessel functions, we analytically show that non-topological dots quite unexpectedly have discrete helical edge states, i.e., Kramers pairs with spin-angular-momentum locking similar to topological dots. These unusual non-topological edge states are geometrically protected due to confinement in a wide range of parameters thus remarkably contrasting the bulk-edge correspondence in TIs. Moreover, for a conduction window with four edge states, we find that the two-terminal conductance G vs. the QD radius R and the gate Vg controlling its levels shows a double peak at 2e 2 /h for both topological and trivial BHZ QDs. Our results blur the boundaries between topological and non-topological phenomena for conductance measurements in small systems such as QDs. This is in stark contrast to conductance measurements in 2D quantum spin Hall and trivial insulators. All of these results were also found in HgTe QDs. Bi-based BHZ dots should also prove important as hosts to room-temperature edge spin qubits.

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confidence: 99%

“…Their spectra feature discrete helical edge states protected against non-magnetic scattering and showing spinangular-momentum locking. These states are potentially important for spintronics [15,16], quantum computation and other quantum technologies [14,17,18].…”

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confidence: 99%

Blurring the Boundaries Between Topological and Nontopological Phenomena in Dots

2018

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“…The topological insulators are narrowgap semiconductors with topological protected edge (surface) states 1,2 . The peculiar properties of these states make topological insulators and their nanostructures useful for future applications ranging from spintronics to quantum computing [3][4][5][6][7][8] . As doping affects transport and optical properties of traditional semiconductors, the influence of impurities to topological insulators has also drawn extensive attention.…”

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confidence: 99%

“…To obtain the first-order equation array, a four-component spinor (4) and H ↑ ψ = Eψ, the equation array are arrived:…”

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confidence: 99%

Coulomb impurities in two-dimensional topological insulators

Zhu

2017

Phys. Rev. B

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Introducing a powerful method, the exact solutions are obtained for a Coulomb impurity in twodimensional infinite and finite topological insulators. The level order and zero-energy degeneracy of the spectra are found to be quite different between topological trivial and nontrivial phases. For quantum dots of topological insulator, the variation of the edge and Coulomb states with dot size, Coulomb potential and magnetic field are clearly shown. It is found that for small dots the edge states can be strongly coupled with the Coulomb states. And, for large dots the edge states are insensitive to the Coulomb fields but sensitive to the magnetic fields.

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“…Their spectra feature discrete helical edge states protected against non-magnetic scattering and showing spinangular-momentum locking. These states are potentially important for spintronics [14,15], quantum computation and other quantum technologies [13,16,17].…”

mentioning

confidence: 99%

Blurring the boundaries between topological and non-topological physical phenomena in dots

Candido¹,

Flatté²,

Egues³

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We investigate the electronic and transport properties of topological and trivial InAs1−xBix quantum dots (QDs). By considering the rapid band gap change within valence band anticrossing theory for InAs1−xBix, we show that Bi-alloyed quantum wells become ∼ 30 meV gapped 2D topological insulators for well widths d > 6.9nm (x = 0.15) and obtain the k.p parameters of the corresponding Bernevig-Hughes-Zhang (BHZ) model. We analytically solve this model for cylindrical confinement via modified Bessel functions. For non-topological dots we find "geometrically protected" discrete helical edge-like states, i.e., Kramers pairs with spin-angular-momentum locking, in stark contrast with ordinary InAs QDs. For a conduction window with four edge states, we find that the twoterminal conductance G vs. the QD radius R and the gate Vg controlling its levels shows a double peak at 2e 2 /h for both topological and trivial QDs. In contrast, when bulk and edge-state Kramers pairs coexist and are degenerate, a single-peak resonance emerges. Our results blur the boundaries between topological and non-topological phenomena for conductance measurements in small systems such as QDs. Bi-based BHZ QDs should also prove important as hosts to edge spin qubits.

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Quantum strain sensor with a topological insulator HgTe quantum dot

Cited by 15 publications

References 31 publications

Blurring the Boundaries Between Topological and Nontopological Phenomena in Dots

Blurring the Boundaries Between Topological and Nontopological Phenomena in Dots

Coulomb impurities in two-dimensional topological insulators

Blurring the boundaries between topological and non-topological physical phenomena in dots

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