Coherent nonlinear transport in quantum rings

Leturcq, R.; Bianchetti, R.; Götz, G.; Ihn, Thomas; Ensslin, Klaus; Driscoll, D. C.; Gossard, A. C.

doi:10.1016/j.physe.2006.08.023

Cited by 10 publications

(5 citation statements)

References 33 publications

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“…3d to gradually evolve at small bias-voltage, a more complex curved pattern is present at larger bias-voltages. 28,29 However, in the WT limit, the lobe structure does not seem to be accompanied by a phase jump of π as reported by Neder et al 12,15 In contrast, clear phase jumps appear in the WB limit as seen in Fig. 3d (filled arrow).…”

Section: Measurements and Discussionsupporting

confidence: 63%

Finite-bias visibility dependence in an electronic Mach-Zehnder interferometer

et al. 2009

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We use an electronic Mach-Zehnder interferometer to explore the non-equilibrium coherence of the electron waves within the edge-states that form in the integral quantum Hall effect. The visibility of the interference as a function of bias-voltage and transmission probabilities of the mirrors, which are realized by quantum point-contacts, reveal an unexpected asymmetry at finite bias when the transmission probability T of the mirror at the input of the interferometer is varied between 0 and 100%, while the transmission probability of the other mirror at the output is kept fixed. This can lead to the surprising result of an increasing magnitude of interference with increasing bias-voltage for certain values of T . A detailed analysis for various transmission probabilities and different directions of the magnetic field demonstrates that this effect is not related to the transmission characteristics of a single quantum point contact, but is an inherent property of the Mach-Zehnder interferometer with edge-states.

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Section: Measurements and Discussionsupporting

confidence: 63%

Finite-bias visibility dependence in an electronic Mach-Zehnder interferometer

et al. 2009

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“…1a). The period of the AB oscillation is 25 mT, being consistent with the lithographic ring geometry with a radius of 230 nm [15]. Figure 1b presents the image plot of the conductance as a function of B and V sd .…”

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confidence: 70%

“…By analyzing the present data as well as those obtained in previous works, the characteristic energy scales of the two effects are found to dominantly depend on the interferometer size. Figure 1a shows the atomic force microscope (AFM) image of the ABR fabricated by local oxidation using an AFM [14] on a GaAs/AlGaAs heterostructure twodimensional electron gas (2DEG) (the electron density 3.7 × 10 11 cm −2 and the mobility 2.7 × 10 5 cm 2 /Vs) [15]. Measurements were performed around zero magnetic field and in the IQH regime.…”

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confidence: 99%

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Universality of bias- and temperature-induced dephasing in ballistic electronic interferometers

et al. 2009

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We performed a transport measurement in a ballistic Aharonov-Bohm ring and a Fabry-Pérot-type interferometer. In both cases we found that the interference signal is reversed at a certain bias voltage and that the visibility decays exponentially as a function of temperature, being in a strong analogy with recent reports on the electronic Mach-Zehnder interferometers. By analyzing the data including those in the previous works, the energy scales that characterize the dephasing are found to be dominantly dependent on the interferometer size, implying the presence of a universal behavior in ballistic interferometers in both linear and non-linear transport regimes.PACS numbers: 73.23. Ad, 71.10.Pm, 85.35.Ds, 03.65.Yz Electron interference has been the central issue in mesoscopic physics since 1980's, which has been promoting our understanding on the phase and coherence of electrons in solids [1]. Recently, an electronic MachZehnder interferometer (MZI) [2] is invoking considerable interest for its possibility to create electron entanglement by two-particle interference [3,4]. This MZI relies on the edge channel transport as it requires chirality of the electron beam, which is also an advantage as the coherence length of the edge electrons is expected to be long. Several experimental works on MZI [2,5,6,7], however, reported that the interference visibility, a measure of coherence, decreases exponentially as the temperature increases. Furthermore, the experimentalists found [5,7,8,9] the so-called "lobe structure", an unexpected phase reversal in the visibility at a certain bias voltage.Several theoretical attempts [10,11,12,13] have tried to explain the observed small energy scales that characterize the lobe structure as well as its drastic temperature dependence. The Coulomb interaction was proposed to be responsible for the observed energy scale proportional to the inverse of the size of MZI [11,12,13]. It is, however, still unclear whether or not the above observations are specific to MZI. Indeed, some theories [12,13] suggest that similar effects may occur in other ballistic interferometers. To investigate this possibility constitutes the central motivation of the present experimental work.Here we report the conductance measurements for an Aharonov-Bohm ring (ABR) around zero magnetic fields and for a Fabry-Pérot-type interferometer (FPI) in the integer quantum Hall (IQH) regime. In both cases, we observed the lobe-like structure and the exponential decay of the visibility with temperature, akin to those in MZI. By analyzing the present data as well as those obtained in previous works, the characteristic energy scales of the two effects are found to dominantly depend on the interferometer size. Figure 1a shows the atomic force microscope (AFM) image of the ABR fabricated by local oxidation using an AFM [14] on a GaAs/AlGaAs heterostructure twodimensional electron gas (2DEG) (the electron density 3.7 × 10 11 cm −2 and the mobility 2.7 × 10 5 cm 2 /Vs) [15]. Measurements were performed around zero magnetic field...

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“…1a) [7,8] . Measurements were performed by using standard lockin technique with 5 !V excitation signal at 37 Hz around zero magnetic field (up to 50 mT) and in the integer quantum hall (IQH) regime (with the Landau level filling ~10).…”

Section: Measurement Setup and Samplementioning

confidence: 99%