Reflection effect of a localized absorptive potential on nonresonant and resonant tunneling

Rubio, Alberto; Kumar, Nandha

doi:10.1103/physrevb.47.2420

Cited by 27 publications

(30 citation statements)

References 9 publications

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“…Inasmuch as (−i 0 ) does not represent a matched reflectionless amplifier, the resulting gain is not a monotonically increasing function of 0 . This point has received some attention [27], and can lead to some subtle effects [28]. Also, so far we have introduced randomness in the real part of the dielectric constant only.…”

Section: Introductionmentioning

confidence: 99%

Coherently amplifying random medium: Statistics of super-reflection

Kumar

Pradhan

Jayannavar

1998

Superlattices and Microstructures

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Section: Introductionmentioning

confidence: 99%

Coherently amplifying random medium: Statistics of super-reflection

Kumar

Pradhan

Jayannavar

1998

Superlattices and Microstructures

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“…This method is better than the optical potential model as it does not suffer from spurious scattering's [9,11,12]. The corrections introduced in case of Optical potential model to take care of spurious scattering's will become manifestly difficult when we calculate the traversal times for a superlattice involving numerous scatterer's.…”

Section: A Wave Attenuation To Measure Conditional Timesmentioning

confidence: 99%

“…In-spite of the fact that a major problem associated with the optical potential has been cured there still remains the problem that in the strong absorption limit it leads to perfect reflection and absorption without reflection(spurious scattering) is not possible [10,11,12]. To overcome this problem, we instead of making the Hamiltonian non-hermitian, add an exponential factor e −αl to the S-Matrix of the system.…”

Section: B Wave Attenuation As a Model For Dephasingmentioning

confidence: 99%

Wave attenuation model for dephasing and measurement of conditional times

Jayannavar

Benjamin

2002

Pramana - J Phys

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Inelastic scattering induces dephasing in mesoscopic systems. An analysis of previous models to simulate inelastic scattering in such systems is presented and also a relatively new model based on wave attenuation is introduced. The problem of Aharonov-Bohm(AB) oscillations in conductance of a mesoscopic ring is studied. We have shown that conductance is symmetric under flux reversal and visibility of AB oscillations decay to zero as function of the incoherence parameter, signalling dephasing. Further wave attenuation is applied to a fundamental problem in quantum mechanics, i.e., the conditional(reflection/transmission) times spent in a given region of space by a quantum particle before scattering off from that region.

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“…This model suffers from some spurious features. 8,9 In the scattering case, in the vicinity of the absorber, the particle experiences a mismatch in the potential ͑being complex͒ and therefore it tries to avoid this region by enhanced back reflection. Thus the IP model plays a dual role of an absorber as well as a reflector, i.e., absorption without reflection is not possible.…”

mentioning

confidence: 99%

Dephasing via stochastic absorption: A case study in Aharonov-Bohm oscillations

Benjamin

Jayannavar

2002

Phys. Rev. B

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The Aharonov-Bohm ring has been the mainstay of mesoscopic physics research since its inception. In this paper we deal with the problem of dephasing of Aharonov-Bohm ͑AB͒ oscillations using a phenomenological model based on stochastic absorption. To calculate the conductance in the presence of inelastic scattering we have used the method due to Brouwer and Beenakker. We have shown that conductance is symmetric under flux reversal and visibility of AB oscillations decay to zero as a function of the incoherence parameter thus signaling dephasing in the system. Some comments are made on the relative merits of stochastic absorption with respect to optical potential model, which have been used to mimic dephasing.Dephasing is defined as the process by which quantum mechanical interference is gradually destroyed. 1,2 Dephasing of electronic phase coherence may be caused by it's interaction with other quasiparticles in the system. The notion of intrinsic decoherence and dephasing of a particle interacting with it's environment is being investigated intensively. For a comparison between theory and experiment, it is necessary to know how dephasing affects the various quantum phenomena related to transport. In our present work we will be interested in modeling dephasing phenomenologically. The Aharonov-Bohm ͑AB͒ interferometer is one of the best examples for analyzing how quantum interference effects are affected by dephasing. In this interferometer the phase of the electrons passing through the arms is modulated by the magnetic flux. It is not unlike the Young's double slit experiment apart from the presence of the magnetic flux. In the Young's double slit interferometer as we know the intensity is given by Iϭ͉⌿͉ 2 ϭ͉ 1 ͉ 2 ϩ͉ 2 ͉ 2 ϩ2 Re( 1 * 2 e i ), the part 2 Re( 1 * 2 e i ) represents the interference term. Here 1 and 2 are the complex wave amplitudes across the upper and lower arms of the interferometer ͑this discussion is restricted to only two partial amplitudes for simplicity͒ and is phase difference between the two wave amplitudes. If there is no phase relationship between the waves then the intensity will be Iϭ͉ 1 ͉ 2 ϩ͉ 2 ͉ 2 . Dephasing thus suppresses the interference terms. In other words dephasing, leads to the vanishing of the off-diagonal elements of the density matrix.Aharonov-Bohm effect in mesoscopic rings manifests itself as a periodic behavior of conductance as a function of magnetic flux piercing the loop. 1 In an AB interferometer the electrons are treated quantum mechanically along the ring and they retain their phase memory across the entire sample and this gives rise to an operative definition of the phase coherence length L or incoherence length. On increasing the temperature L becomes less than the size of the ring and the phase coherence in the system gradually disappears and as a consequence the AB effect ͑the visibility of the AB oscillations͒ vanishes. Typically L scales with temperature T in a power law form, i.e., L ϭT Ϫp (p lies in the range 1 to 2͒.There are different ways to model dep...

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Reflection effect of a localized absorptive potential on nonresonant and resonant tunneling

Cited by 27 publications

References 9 publications

Coherently amplifying random medium: Statistics of super-reflection

Coherently amplifying random medium: Statistics of super-reflection

Wave attenuation model for dephasing and measurement of conditional times

Dephasing via stochastic absorption: A case study in Aharonov-Bohm oscillations

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