Einselection in Action: Decoherence and Pointer States in Open Quantum Dots

Ferry, D. K.; Akis, R.; Bird, J. P.

doi:10.1103/physrevlett.93.026803

Cited by 75 publications

(45 citation statements)

References 24 publications

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“…The readout of information from a quantum mechanical system with a classical apparatus presumes the knowledge of the transition between the classical and quantum mechanical world [3]. Open quantum dots (QD), exhibit interesting laboratories in which to study this transition [4][5][6][7]. Open QDs, in contrast to closed quantum dots, for example, [8] are strongly coupled to the nearby electron reservoirs or environment.…”

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confidence: 99%

“…Pointer states eventually correspond to classical states that are persistent to environmental monitoring during the measurement process [3]. They have been investigated in nanostructures so far by direct transport measurements [4][5][6][7] and indirect imaging by using the Fourier transformed scanning probe technique [10]. In the latter, additional environmental perturbation is induced to the open quantum dot by scanning a biased atomic force microscope (AFM) tip over the area of interest.…”

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confidence: 99%

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Direct Imaging of Electron States in Open Quantum Dots

et al. 2012

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We use scanning gate microscopy to probe the ballistic motion of electrons within an open GaAs=AlGaAs quantum dot. Conductance maps are recorded by scanning a biased tip over the open quantum dot while a magnetic field is applied. We show that, for specific magnetic fields, the measured conductance images resemble the classical transmitted and backscattered trajectories and their quantum mechanical analogue. In addition, we prove experimentally, with this direct measurement technique, the existence of pointer states. The demonstrated direct imaging technique is essential for the fundamental understanding of wave function scarring and quantum decoherence theory.

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Direct Imaging of Electron States in Open Quantum Dots

et al. 2012

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“…In particular, the concept of einselection of pointer states has been very successful in explaining the general behavior of quantum particles subjected to decoherence effects both from a fundamental point of view [7,8] and in solid-state nanostructures such as open quantum dots [9]. The Wigner function is recognized as a convenient formalism to study these processes theoretically [8,10], or experimentally [11].…”

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Physical scales in the Wigner–Boltzmann equation

et al. 2013

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The Wigner–Boltzmann equation provides the Wigner single particle theory with interactions with bosonic degrees of freedom associated with harmonic oscillators, such as phonons in solids. Quantum evolution is an interplay of two transport modes, corresponding to the common coherent particle-potential processes, or to the decoherence causing scattering due to the oscillators. Which evolution mode will dominate depends on the scales of the involved physical quantities. A dimensionless formulation of the Wigner–Boltzmann equation is obtained, where these scales appear as dimensionless strength parameters. A notion called scaling theorem is derived, linking the strength parameters to the coupling with the oscillators. It is shown that an increase of this coupling is equivalent to a reduction of both the strength of the electric potential, and the coherence length. Secondly, the existence of classes of physically different, but mathematically equivalent setups of the Wigner–Boltzmann evolution is demonstrated.

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“…La,73.63.Nm Planar nanodevices containing single [1,2,3,4,5,6], double [7,8,9,10], and multiple [11,12] laterally coupled quantum dots with confinement potential tuned by electrodes deposited on top of the semiconductor heterostructure are at present extensively studied in both theory and experiment in context of application for quantum gates using electron spins as quantum bits. Recent advances include demonstration that the electron spin can be set and read-out [2,4,5,6,7,8,9,13] as well as rotated [6,13].…”

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“…1) is of a square shape with side length b. We solve equations (1)(2)(3)(4)(5)(6)(7)(8) and evaluate the average diameter of the electron wave packet…”

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Induced Quantum Dots and Wires: Electron Storage and Delivery

et al. 2008

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We show that quantum dots and quantum wires are formed underneath metal electrodes deposited on a planar semiconductor heterostructure containing a quantum well. The confinement is due to the self-focusing mechanism of an electron wave packet interacting with the charge induced on the metal surface. Induced quantum wires guide the transfer of electrons along metal paths and induced quantum dots store the electrons in specific locations of the nanostructure. Induced dots and wires can be useful for devices operating on the electron spin.PACS numbers: 73.21. La,73.63.Nm Planar nanodevices containing single [1,2,3,4,5,6], double [7,8,9,10], and multiple [11,12] laterally coupled quantum dots with confinement potential tuned by electrodes deposited on top of the semiconductor heterostructure are at present extensively studied in both theory and experiment in context of application for quantum gates using electron spins as quantum bits. Recent advances include demonstration that the electron spin can be set and read-out [2,4,5,6,7,8,9,13] as well as rotated [6,13]. In a quantum gate working on the electron spins [14] the single qubit operations are to be performed with an electron transfer to a high g factor region or to a ferromagnetic quantum dot where the electron spin is rotated by microwave radiation. In this letter we present an idea for the control of the electron localization and its transfer between specific locations within the nanodevice. The idea is based on the self-focusing mechanism of an electron wave packet near a conductor surface [15,16,17] which as we show below allows to exclude scattering during the electron transfer and warrants the electron delivery to a specific location in the device with a 100% probability.In the conventional planar nanodevices [1, 2] a negative potential is applied to the gate electrodes to deplete the two-dimensional electron gas underneath. In the variant of the structure proposed below the role of the electrodes is different: a single quantum-well-confined electron becomes self-trapped below the conductor by the potential of the charge that it induces on the metal surface. The response potential of the electron gas of the conductor contains a component of lateral confinement which localizes the quantum-well-confined electron in form of a wave packet that moves parallel to the metal preserving its shape as an electron soliton [15,16]. The packed was called [17] an inducton since the focusing potential stems from the charge induced in the electron gas. The inducton possesses mixed quantum and classical properties. It is described by a wave function of both spatial and spin coordinates whose time evolution is described by the Schroedinger equation. On the other hand the inducton moves as a stable wave packet of a finite size and its transition probability in transport through potential barriers is binary (0 or 1) [16]. In Ref.[16] we discussed a structure of planar infinite layers of metal, insulator (or semiconducting blocking barrier) and a quantum well in which the i...

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Einselection in Action: Decoherence and Pointer States in Open Quantum Dots

Cited by 75 publications

References 24 publications

Direct Imaging of Electron States in Open Quantum Dots

Direct Imaging of Electron States in Open Quantum Dots

Physical scales in the Wigner–Boltzmann equation

Induced Quantum Dots and Wires: Electron Storage and Delivery

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