Nonlocal bias spectroscopy of the self-consistent bound state in quantum point contacts near pinch off

Yoon, Young-Soo; Kang, Min-Sung; Ivanushkin, Pavel; Mourokh, Lev G.; Reno, John L.; Bird, J. P.

doi:10.1063/1.3142418

Cited by 13 publications

(37 citation statements)

References 24 publications

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“…Confirming that this feature is associated uniquely with physics that arises near pinch-off, no other resonances are observed as higher subbands of the swept QPC are subsequently populated. The resonance is reproduced, however, in devices with different gate configurations [22,24], in various QPCs fabricated on the same chip [24][25][26], and in multiple cooling cycles performed over a period of several years. From these collective observations, we are able to infer that the resonance does indeed result from the intrinsic properties of the QPC and is not a random-impurity effect.…”

Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 98%

“…1. Schematic illustration of the Fano resonance exhibited by a detector QPC that is coupled through a region of two-dimensional electron gas to a bound state in another QPC [22][23][24][25][26]. An electrochemical-potential difference between source and drain is used to drive electrons (thick red line) through the detector.…”

Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 99%

“…The microscopic structure of this BS remains the subject of debate [35,36], however, so that further experiments are called for to confirm its existence. Utilizing the FR as a key signature of the presence of a discrete state, we have implemented a mesoscopic version of the FR experiment, in which the mutual interaction between a pair of coupled QPCs reveals the signature of the BS [22][23][24][25][26]. In these experiments, one QPC (the detector) is configured with fixed gate bias, while the gate voltage applied to the second (swept) QPC is varied continuously, driving it to pinch-off where BS formation is expected.…”

Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 99%

“…Since our experimental demonstration of the continuummediated coupling is based on exploiting the specific properties of quantum point contacts (QPCs) near pinch-off, in Sec. II we first briefly review our recent work [22][23][24][25][26] in which we have shown how these structures may be used as an on-demand source of a localized quantum state. In Sec.…”

Section: Introductionmentioning

confidence: 99%

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Coupling Quantum States through a Continuum: A Mesoscopic Multistate Fano Resonance

et al. 2012

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We demonstrate a fully tunable realization of a multistate Fano resonance, in which a pair of remote quantum states experience an effective coupling due to their mutual overlap with a continuum. Our mesoscopic implementation of this system exploits the ability of the semiconductor nanostructures known as quantum point contacts (QPCs) to serve, in the low-density limit close to pinch-off, as an on-demand localized state. By coupling the states formed on two separate QPCs, through a two-dimensional electron gas that serves as a continuum, we observe a robust effective interaction between the QPCs. To explain this result, we develop a theoretical formulation, based on the ideas of the Schrieffer-Wolff transformation, which is able to reproduce our key experimental findings. According to this model, the robust character of the interaction between the two remote states arises from the fact that the interaction is essentially mediated by a large number of degenerate continuum states. While the continuum is often viewed as a source of decoherence, our experiment therefore instead suggests the possibility of using this medium to support the interaction of quantum states, a result that may allow new approaches to coherently couple nanostructures in extended geometries.

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Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 98%

Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 99%

Section: Bound-state Formation In Quantum Point Contactsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coupling Quantum States through a Continuum: A Mesoscopic Multistate Fano Resonance

et al. 2012

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“…However, if they exist, QBSs can radically affect the properties of a system. For example, they might trap electrons and produce local magnetic moments [5][6][7][8][9][10][11][12], which can cause spin-dependent transpsort through a QPC.…”

Section: Introductionmentioning

confidence: 99%

Formation mechanism of bound states in graphene point contacts

2014

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Electronic localization in narrow graphene constrictions are theoretically studied, and it is found that long-lived (∼ 1 ns) quasi-bound states (QBSs) can exist in a class of ultra-short graphene quantum point contacts (QPCs). These QBSs are shown to originate from the dispersionless edge states that are characteristic of the electronic structure of generically terminated graphene in which pseudo time-reversal symmetry is broken. The QBSs can be regarded as interface states confined between two graphene samples and their properties can be modified by changing the sizes of the QPC and the interface geometry. In the presence of bearded sites, these QBS can be converted into bound states. Experimental consequences and potential applications are discussed.

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Talking through the continuum: New manifestations of Fano‐resonance phenomenology realized with mesoscopic nanostructures

Xiao

Xiang

Yoon

et al. 2012

Fortschritte der Physik

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The focus of this review is recent work in which we have demonstrated a highly‐flexible approach to the study of Fano‐resonance phenomena, by making use of the mesoscopic devices known as quantum point contacts (QPCs). Utilizing the ability of these structures to function as an “on‐demand quantum state”, we demonstrate a highly‐flexible system for the investigation of Fano resonances. Our approach involves making measurements of non‐locally coupled pairs of QPCs, one of which is used to form the discrete state needed for the Fano resonance, while the other serves as a detector whose conductance is sensitive to the energy of this state. As a demonstration of the flexibility of this approach, we show how it can be used to implement a “multi‐state” Fano resonance, in which two discrete states undergo a robust interaction that is achieved by coupling them to each other through a common continuum.

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Nonlocal bias spectroscopy of the self-consistent bound state in quantum point contacts near pinch off

Cited by 13 publications

References 24 publications

Coupling Quantum States through a Continuum: A Mesoscopic Multistate Fano Resonance

Coupling Quantum States through a Continuum: A Mesoscopic Multistate Fano Resonance

Formation mechanism of bound states in graphene point contacts

Talking through the continuum: New manifestations of Fano‐resonance phenomenology realized with mesoscopic nanostructures

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