Observation of the Aharonov-Bohm effect for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>ω</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>τ&gt;1

Timp, G.; Chang, A. M.; Cunningham, J. E.; Chang, T.Y.; Mankiewich, P. M.; Behringer, R. E.; Howard, Richard

doi:10.1103/physrevlett.58.2814

Cited by 302 publications

(134 citation statements)

References 12 publications

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“…This compares well with the increase in width between two consecutive steps, determined from the experiment. Equation (4) may also be viewed äs a special case of the multichannel Landauer formula, 12 " 14 -Σ η,m ™ 1 t n n (5) for transmission coefficients | t nm \ =ö" m corresponding to ballistic transport with no channel mixing.…”

Section: T Foxon Philips Research Laboratories Redhill Surrey Rh1 mentioning

confidence: 99%

Quantized conductance of point contacts in a two-dimensional electron gas

et al. 1988

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Ballistic pomt contacts, defined in the two-dimensional electron gas of a GaAs-AlGaAs heterostructure, have been studied in zero magnetic field The conductance changes in quantized Steps of e 2 /nh when the width, controlled by a gate on top of the heterojunction, is vaned Up to sixteen Steps are observed when the pomt contact is widened from 0 to 360 nm An explanation is proposed, which assumes quantized transverse momentum in the pomt-contact region As a result of the high mobihty attamable in the twodimensional electron gas (2DEG) in GaAs-AlGaAs heterostructures it is now becoming feasible to study ballistic transport in small devices '" 6 In metals ideal tools for such studies are constnctions havng a width W and length L much smaller than the mean free path l e These are known äs Sharvin pomt contacts 7 Because of the ballistic transport through these constnctions, the resistance is determmed by the pomt-contact geometry only Point contacts have been used extensively for the study of elastic and melastic electron scattermg With use of biased pomt contacts, electrons can be mjected mto metals at energies above the Fermi level This allows the study of the energy dependence of the scattermg mechamsms 8 With the use of a geometry containmg two pomt contacts, with Separation smaller than l e , electrons mjected by a pomt contact can be focused mto the other contact, by the application of a magnetic field This technique (transverse electron focusmg) has been applied to the detailed study of Fermi surfaces 9 In this Letter we report the first expenmental study of the resistance of ballistic pomt contacts m the 2DEG of high-mobihty GaAs-AlGaAs heterostructures The smgle-pomt contacts discussed m this paper are part of a double-pomt-contact device The results of transverse electron focusmg m these devices will be published elsewhere '° The pomt contacts are dehned by electrostatic depletion of the 2DEG underneath a gate This method, which has been used by several authors for the study of l D conduction,' 1 offers the possibility to control the width of the pomt contact by the gate voltage Control of the width is not feasible in metal pomt contacts The classical expression for the conductance of a pomt contact m two dimensions (see below) is G=(e 2 /nh)k Y W/n(1) in which kf is the Fermi wave vector and W is the width of the contact This expression is vahd if l e » W and the Fermi wavelength λρ<ίί W The first condition is satisfied in our devices, which have a maximum width W mm «= 250 nm and l e =8 5 μηι The second condition should also hold when the devices have the maximum width We expect quantum effects to become important when the width becomes comparable to λρ, which is 42 nm m our devices In this way we are able to study the transition from classical to quantum ballistic transport through the pomt contactThe pomt contacts are made on high-mobility molecular-beam-epitaxy-grown GaAs-AlGaAs heterostructures The electron density of the matenal is 3 56xl0 15 /m 2 and the mobihty 85 m 2 /V s (at 0 6 K) These values ...

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Section: T Foxon Philips Research Laboratories Redhill Surrey Rh1 mentioning

confidence: 99%

Quantized conductance of point contacts in a two-dimensional electron gas

et al. 1988

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“…Open rings connected to leads allow the observation of the Aharonov-Bohm effect [1], a paradigm of quantum mechanical phase coherence [2,3]. The phase coherence of transport through a quantum dot embedded in one arm of an open ring has been demonstrated [4].…”

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confidence: 99%

Energy spectra of quantum rings

Fuhrer

Lüscher

Ihn

et al. 2001

Nature

473

416

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Ring geometries have fascinated experimental and theoretical physicists over many years. Open rings connected to leads allow the observation of the Aharonov-Bohm effect [1], a paradigm of quantum mechanical phase coherence [2,3]. The phase coherence of transport through a quantum dot embedded in one arm of an open ring has been demonstrated [4]. The energy spectrum of closed rings [5] has only recently been analysed by optical experiments [6,7] and is the basis for the prediction of persistent currents [8] and related experiments [9-11]. Here we report magnetotransport experiments on a ring-shaped semiconductor quantum dot in the Coulomb blockade regime [12]. The measurements allow us to extract the discrete energy levels of a realistic ring, which are found to agree well with theoretical expectations. Such an agreement, so far only found for few-electron quantum dots, is here extended to a many-electron system [13]. In a semiclassical language our results indicate that electron motion is governed by regular rather than chaotic motion, an unexplored regime in many-electron quantum dots.

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“…3, or by narrowing the 1D-channel confinement potential. Alternatively, one could employ the Aharonov-Bohm effect, which has already been observed in GaAs/AlGaAs heterostructure devices [16].…”

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confidence: 99%

Surface-acoustic-wave single-electron interferometry

Rodriquez

Kataoka

et al. 2005

Phys. Rev. B

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We propose an experiment to observe interference of a single electron as it is transported along two parallel quasi-one-dimensional channels trapped in a single minimum of a travelling periodic electric field. The experimental device is a modification of the surface acoustic wave (SAW) based quantum processor. Interference is achieved by creating a superposition of spatial wavefunctions between the two channels and inducing a relative phase shift via either a transverse electric field or a magnetic field. The interference can be used to estimate the decoherence time of an electron in this type of solid-state device.Constructing a solid-state single-electron interferometer poses many challenges, especially single-electron transport through the device. Recent experiments on electron interferometers [1,2] and double quantum dots [3] have demonstrated interference, but do not deal with single electrons. These experiments have to take into account many-particle effects, the behaviour of electrons as quasi-particles, and the validity of the application of theories such as Fermi liquid theory. Besides not showing true single particle interference, these factors obscure the fundamental electron coherence time, which is of crucial importance for many prospective solid state quantum information processing schemes [4,5,6,7,8].Electron quantization using surface acoustic waves (SAW), originally studied in the context of current standards [9,10], has recently lead to a proposal for the implementation of a quantum processor in the solid-state that uses this mechanism [11]. Advantages of the proposed SAW devices include the unique feature of creating a completely polarised initial state and of making ensemble measurements over billions of identical computations. Additionally, these systems are similar to quantum dots, but have the advantage that manipulation of qubits can be done with static potentials on surface gates without the need for expensive high-frequency pulse generation [3]. Furthermore, the mechanism of SAW transport eliminates the problem of backscattering from discontinuities in the electron trajectory which also detracts from the ideal interferometry experiment [22] [23]. This opens up the range of mechanisms for inducing relative phase shifts required to observe interference fringes.The acoustoelectric devices we consider in this paper are fabricated on modulation doped GaAs-AlGaAs heterostructures. Because GaAs is a piezoelectric material, applying a radio-frequency potential difference between a pair of interdigitated transducers produces vibrations that propagate through the structure as longitudinal waves (SAWs), which in turn induce an electrostatic potential. The SAWs then travel across the 2-dimensional electron gas and through a mesa patterned with surface gates that define two parallel quasi-onedimensional channels. By altering the static potential on the surface gates it is possible to trap a single electron in each SAW potential minimum in each of the two channels with an accuracy greater than 1 part...

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Observation of the Aharonov-Bohm effect forωcτ>1

Cited by 302 publications

References 12 publications

Quantized conductance of point contacts in a two-dimensional electron gas

Quantized conductance of point contacts in a two-dimensional electron gas

Energy spectra of quantum rings

Surface-acoustic-wave single-electron interferometry

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