Phase Breaking as a Probe of the Intrinsic Level Spectrum of Open Quantum Dots

Bird, J. P.; Linke, Heiner; Cooper, J. R.; Micolich, A. P.; Ferry, D. K.; Akis, R.; Ochiai, Y.; Taylor, R. P.; Newburry, R.; Omling, P.; Aoyagi, Yoshinobu; Sugano, Takuo

doi:10.1002/1521-3951(199711)204:1<314::aid-pssb314>3.0.co;2-a

Cited by 13 publications

(7 citation statements)

References 9 publications

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“…Shorter trajectories may well survive, and we see two separate categories of these. The first are skipping orbits as highlighted by Christensson et al [127], and used for studying phase-breaking in dots by Bird et al [86][87][88]. These are likely protected from disorder scattering by the short distance between bounces combined with a field-induced curvature mechanism similar to that involved in the quantum Hall effect [128].…”

Section: Discussionmentioning

confidence: 99%

“…where m * is the electron effective mass and τ q is the lifetime of the quantum states, obtained using a skipping orbit analysis [86][87][88]. 5 Remarkably, D F is found to take its maximum value ∼ 1.52 at Q = 1, with D F falling in either direction, reaching the non-fractal value D F = 1 in the limits Q = 0 and Q ∼ 10.…”

Section: Early Pictures Of Quantum Chaos In Semiconductor Billiardsmentioning

confidence: 98%

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Is it the boundaries or disorder that dominates electron transport in semiconductor `billiards'?

Micolich¹,

See²,

Scannell³

et al. 2012

Fortschritte der Physik

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Key words quantum chaos, semiconductor billiards, quantum dots, ballistic transport Semiconductor billiards are often considered as ideal systems for studying dynamical chaos in the quantum mechanical limit. In the traditional picture, once the electron's mean free path, as determined by the mobility, becomes larger than the device, disorder is negligible and electron trajectories are shaped by specular reflection from the billiard walls alone. Experimental insight into the electron dynamics is normally obtained by magnetoconductance measurements. A number of recent experimental studies have shown these measurements to be largely independent of the billiards exact shape, and highly dependent on sample-tosample variations in disorder. In this paper, we discuss these more recent findings within the full historical context of work on semiconductor billiards, and offer strong evidence that small-angle scattering at the sub-100 nm length-scale dominates transport in these devices, with important implications for the role these devices can play for experimental tests of ideas in quantum chaos.

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Section: Discussionmentioning

confidence: 99%

Section: Early Pictures Of Quantum Chaos In Semiconductor Billiardsmentioning

confidence: 98%

Is it the boundaries or disorder that dominates electron transport in semiconductor `billiards'?

Micolich¹,

See²,

Scannell³

et al. 2012

Fortschritte der Physik

Self Cite

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“…In temperature dependent studies, these authors have found that their data for τ φ are best fitted by a T −1 variation, consistent with the experiments above. They also find a saturation of τ φ at temperatures lower than the average level spacing in the dot ( , where = 2πh 2 /m * A and A is the effective area of the dot), a conclusion that is supported by the scaling of the saturation temperature with dot size [48]. Bird et al have also used the same technique to determine the variation of the phase-breaking time with lead opening and find a strong enhancement of τ φ as the leads are narrowed to support a few modes [38] (figure 4).…”

Section: Studies Of Electron Dephasing In Quantum Dotsmentioning

confidence: 91%

Recent experimental studies of electron transport in open quantum dots

Bird

1999

J. Phys.: Condens. Matter

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Recent advances in semiconductor microprocessing technology now allow the realization of sub-micron sized quantum dots, which are quasi-zero-dimensional devices in which current flow is confined on length scales approaching the Fermi wavelength of the electrons. The influence of disorder is thought to be strongly suppressed in these devices, so that electrons propagate while mainly undergoing large-angle scattering at the walls of the dot. At sufficiently low temperatures, electron phase coherence is maintained over long distances and coherent interference of electrons becomes an important process in determining the electrical behaviour of the dots. In this review, we focus on a number of issues revealed by recent experimental studies of open dots, such as fractal magneto-conductance fluctuations, wavefunction scarring due to selectively excited periodic orbits, and novel `ratchet' behaviour in non-equilibrium studies.

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“…K decreased q, increases, saturating at 420mK and 125mK for the 0.6 and lpm billiards respectively. This saturation occurs once the thermal smearing is sufficiently reduced for the discrete energy level structure of the billiard to be resolved [15,16]. The temperature TQ where this occurs is:…”

mentioning

confidence: 99%

“…where AB is the billiard area and hE is the energy level spacing of the billiard [15,16]. The saturation temperatures we observe are very close to those calculated using (4) for the billiards investigated.…”

mentioning

confidence: 99%

The temperature dependent fractal dimension of magneto-conductance fluctuations in semiconductor billiards

Micolich

Taylor²,

Newbury³

et al.

1998 Conference on Optoelectronic and Microelectronic Materials and Devices. Proceedings (Cat. No.98EX140)

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We present investigations of the fractal behaviour of magneto-conductance fluctuations in semiconductor billiards as a function of temperature. The introduction of finite phase coherence by nonzero temperatures is found not to suppress fractal behaviour in the experimental data. Instead, we show that the fractal dimension decreases with increasing temperature and we present a remarkable similarity between the phase coherence time and the fractal dimension.c 1999 Academic Press Key words: fractal, semiconductor billiards, quantum chaos.Quantum interference (QI) effects between phase coherent electron waves in mesoscopic billiards generate highly reproducible fluctuations in conductance G with varying magnetic field B [1]. These magnetoconductance fluctuations (MCF) provide an important probe of electron dynamics in the semiclassical limit. The application of a negative bias to metallized gates deposited on the surface of AlGaAs/GaAs heterostructures allow the definition of submicron billiards in the two-dimensional electron gas (2DEG) formed at the AlGaAs/GaAs interface. High quality heterostructure material provides an environment where the electronic mean free path exceeds the billiard dimension. Hence, billiard geometry rather than random impurity distributions determine electron trajectories, and ballistic transport prevails [2,3]. Traditionally, it has been assumed that the billiard confining potential can be approximated by an infinite square potential well [2][3][4]. Recently, however, theoretical studies of realistic 'soft-wall' potentials and their effects on billiard electron dynamics have become popular [5,6]. Investigations suggest that soft-wall potentials generate a mixed classical phase space where the trajectory trapping effect of Cantori on the chaotic/nonchaotic boundary produce a power-law distribution of electron trajectory loop areas [6]. For a semiclassical model, the magnetic field period content †

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Phase Breaking as a Probe of the Intrinsic Level Spectrum of Open Quantum Dots

Cited by 13 publications

References 9 publications

Is it the boundaries or disorder that dominates electron transport in semiconductor `billiards'?

Is it the boundaries or disorder that dominates electron transport in semiconductor `billiards'?

Recent experimental studies of electron transport in open quantum dots

The temperature dependent fractal dimension of magneto-conductance fluctuations in semiconductor billiards

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