Long-range spin coherence in a strongly coupled all-electronic dot-cavity system

Ferguson, Michael S.; Oehri, David; Rössler, C.; Ihn, Thomas; Ensslin, Klaus; Blatter, G.; Zilberberg, Oded

doi:10.1103/physrevb.96.235431

Cited by 13 publications

(20 citation statements)

References 62 publications

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“…In addition, oscillations appear on the scale of λ/2 due to interferences of wave-like elements with the reflection from the boundary. These interferences lead to measurable effects when the radius of the mirror cavity is varied [14,26,27].…”

Section: Branches and Scattering Wave Functionsmentioning

confidence: 99%

Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities

et al. 2021

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We demonstrate the emergence of classical features in electronic quantum transport for the scanning gate microscopy response in a cavity defined by a quantum point contact and a micron-sized circular reflector. The branches in electronic flow characteristic of a quantum point contact opening on a two-dimensional electron gas with weak disorder are folded by the reflector, yielding a complex spatial pattern. Considering the deflection of classical trajectories by the scanning gate tip allows to establish simple relationships of the scanning pattern, which are in agreement with recent experimental findings.

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Section: Branches and Scattering Wave Functionsmentioning

confidence: 99%

Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities

et al. 2021

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“…The more complex the internal structure of a quantum impurity is, the broader the variety of many-body phenomena that can arise. An example of such a structured quantum impurity problem involves an electronic dot-cavity system [26]. The model's impurity consists of a quantum dot that is coupled to an electronic cavity, i.e., to a discrete set of electronic noninteracting levels.…”

mentioning

confidence: 99%

“…The model's impurity consists of a quantum dot that is coupled to an electronic cavity, i.e., to a discrete set of electronic noninteracting levels. The dot-cavity impurity is weakly coupled to three electron leads [26]. Note that the dot-cavity resembles a two-dot system [27,28], where one of the two dots is large and noninteracting, i.e., it is equivalent to a so-called Kondo box [29] in the large level-spacing limit.…”

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confidence: 99%

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Entanglement based observables for quantum impurities

Stocker¹,

Sack²,

Ferguson³

et al. 2022

Preprint

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Quantum impurity systems exhibit fascinating many-body phenomena when the small interacting impurity changes the physics of a large noninteracting environment. The characterisation of such strongly-correlated non-perturbative effects is particularly challenging due to the infinite size of the environment, and the inability of local correlators to capture the build-up of long-ranged entanglement in the system. Here, we devise an entanglement-based observable -the purity of the impurity -as a witness for the formation of strong correlations. We showcase the utility of our scheme when exactly solving the open Kondo box model in the small box limit, corresponding to allelectronic dot-cavity devices. Thus, we characterise the experimentally-observed metal-to-insulator phase transition in the system and identify how the (conducting) dot-lead Kondo singlet is quenched by an (insulating) intra-impurity singlet formation. Our work showcases that quantum information observables serve as excellent order parameters for the characterisation of strong correlation, and motivates experimental observation of the purity of mesoscopic devices as entanglement witnesses.

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“…It is therefore of fundamental interest to investigate coupling between discrete quantum devices. Coupling between electronic cavity and other quantum devices, such as quantum point contact [3][4][5][6][7] (QPC) and quantum dot [8][9][10] (QD), has attracted considerable attention. A hybrid device consisting of a QPC and an electronic cavity, as an example, provides a unique platform to investigate electronic equivalent of optical phenomena.…”

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confidence: 99%

Magnetoresistance in an electronic cavity coupled to one-dimensional systems

Yan

Kumar

See

et al. 2018

Applied Physics Letters

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In the present work we performed magnetoresistance measurement in a hybrid system consisting of an arc-shaped quantum point contact (QPC) and a flat, rectangular QPC, both of which together form an electronic cavity between them. The results highlight a transition between collimation-induced resistance dip to a magnetoresistance peak as the strength of coupling between the QPC and the electronic cavity was increased. The initial results show the promise of hybrid quantum system for future quantum technologies.Recent development in quantum technologies has stimulated research activities in integrating different quantum components in order to realize complex functionality 1,2 . It is therefore of fundamental interest to investigate coupling between discrete quantum devices. Coupling between electronic cavity and other quantum devices, such as quantum point contact 3-7 (QPC) and quantum dot 8-10 (QD), has attracted considerable attention. A hybrid device consisting of a QPC and an electronic cavity, as an example, provides a unique platform to investigate electronic equivalent of optical phenomena. This may be understood from the fact that electrons in such a system transport ballistically and accumulate phase along the quasi-classical trajectories, which is a close analogue of an optical cavity. Previous studies based on QPC-cavity hybrid devices reported results based on classical trajectories of electrons 3,4,11,12 as well as quantum effects manifested as conductance fluctuations 3,4 and Ahronov-Bohm phase shift as a function of cavity size 4 .In the present work, we studied magnetoresistance in a hybrid system in a controlled manner with the assistance of two QPCs which form an electronic cavity between them. We show the strength of coupling between the QPC and cavity states can be monitored by oscillation in the magnitude of central peak/dip in magnetoresistance.The devices studied in the work were fabricated from a high mobility two-dimensional electron gas (2DEG) formed at the interface of GaAs/Al 0.33 Ga 0.67 As heterostructure. The measured electron density (mobility) was 1.80×10 11 cm −2 (2.17×10 6 cm 2 V −1 s −1 ) at 1.5 K, which ensured that both the calculated mean free path and phase coherence length 13,14 were over 10 µm which were larger than electron propagation length. The experiments were performed in a cryofree dilution refrigerator with a lattice temperature of 20 mK using the standard lockin technique.The hybrid device consists of a pair of arc-shaped gates with a QPC (referred as arc-QPC) forming in the center of arc-gates and another pair of rectangular QPC (named as flat-QPC) as depicted in Fig. 1. The QPCs are assembled in such a way that the geometrical center of the arc (shaped gates) aligns with the saddle point of the flat-QPC. An electronic cavity is formed when QPCs are activated by depleting the 2D electrons underneath the

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Long-range spin coherence in a strongly coupled all-electronic dot-cavity system

Cited by 13 publications

References 62 publications

Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities

Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities

Entanglement based observables for quantum impurities

Magnetoresistance in an electronic cavity coupled to one-dimensional systems

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