Reduction of quantized conductance at low temperatures observed in 2 to 10 μm-long quantum wires

Tarucha, Seigo; Honda, Takashi; Saku, T.

doi:10.1016/0038-1098(95)00102-6

Cited by 414 publications

(394 citation statements)

References 10 publications

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“…From above equation it is possible to deduce that the number of δω s that fulfill the equation, i.e., the number of ECMs, increases with the feedback strength K fb . The ECMs always appear in pairs in saddle-node bifurcations, with one of them being always unstable [TAR95]. For high feedback strengths, a high number of ECMs coexist, which makes multi-stability a commonly encountered phenomenon [LEN91,HEI03a,FLU09,KIM14].…”

Section: Quantum-dot Laser Dynamics Under Optical Feedbackmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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In this thesis the dynamics and performance of optoelectronic devices based on semiconductor quantum-dots are investigated.In the first part, the dynamics of quantum-dot lasers under external perturbations is discussed. Using a microscopically based balance equation model that incorporates detailed charge-carrier scattering dynamics and the possibility to describe nonequilibrium between intra-band electronic states, the relaxation oscillations of the quantum-dot laser are investigated. Three qualitatively different dynamic regimes are identified in dependence of the scattering rates -the "constantreservoir" regime for slow scattering, the "overdamped" regime, and the "synchronized" regime for high scattering -characterized by a varying degree of nonequilibrium between the quantum-dot and reservoir states.Important differences to conventional lasers are found in the modulation response and the dynamics in optical injection and feedback setups. Common theoretical models and approaches used to describe these applications are shown to yield inaccurate predictions, especially in the "constant-reservoir" and "overdamped" dynamic regimes. An important consequence is that the amplitude-phase coupling in quantum-dot lasers, commonly described by the α-factor, differs from conventional descriptions due to the desynchronization of gain and refractive index. While the α-factor describes bifurcations of fixed points accurately, it fails in describing dynamic solutions and overestimates the extent of complex dynamics. The observed low sensitivity to optical perturbations in quantum-dot lasers can therefore be attributed partly to the charge-carrier nonequilibrium. Three quantum-dot laser models on different levels of sophistication are presented that can accurately describe the quantum-dot nonequilibrium dynamics.In the second part of the thesis, the performance of quantum-dot semiconductor optical amplifiers is investigated, and two types of applications unique to quantum-dots as active medium are discussed. The ground and excited states of the quantum-dots allow an ultra-broad-band amplification of optical data streams. Amplified signals on the ground-state frequencies are shown to generally exhibit higher quality than on the excited state, due to a lower sensitivity of the groundstate to carrier-density variations. Nevertheless the quantum-dot amplifier is found to allow effective amplification on both frequency ranges. Furthermore, a parameter range is identified that allows for a simultaneous amplification of data signals on the ground and excited state in a counter-propagating setup.The long microscopically polarization dephasing times in quantum-dots are found to enable quantum-coherent interactions on a macroscopic scale at room-temperature. By comparison with experiments, the occurrence of Rabi-oscillations by amplification of ultra-short pulses is demonstrated. Quantum-dot based devices could therefore be used for future applications based on quantum-coherent effects.

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Section: Quantum-dot Laser Dynamics Under Optical Feedbackmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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“…Values of 0 between 2.5 and 3.5 meV have been determined for the gate voltage close to the threshold of the second subband for long quantum wires using a magnetic depopulation technique. 44 We discuss the case in which the logarithmic Hartree potential has been included, which we call the Hartree model, and the case in which the Hartree potential is not taken into account in the KS equations, which we call the exchange-correlation model.…”

Section: A Phase Diagram Of the Quantum Strip In The Kohn-sham Framementioning

confidence: 99%

Ground state structure and conductivity of quantum wires of infinite length and finite width

et al. 2005

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We have studied the ground state structure of quantum strips within the local spin-density approximation, for a range of electronic densities between ϳ5 ϫ 10 4 and 2 ϫ 10 6 cm −1 and several strengths of the lateral confining potential. The results have been used to address the conductance G of quantum strips. At low density, when only one subband is occupied, the system is fully polarized and G takes a value close to 0.7͑2e 2 / h͒, decreasing with increasing electron density in agreement with experiments. At higher densities the system becomes paramagnetic and G takes a value near ͑2e 2 / h͒, showing a similar decreasing behavior with increasing electron density. In both cases, the physical parameter that determines the value of the conductance is the ratio K / K 0 of the compressibility of the system to the free one.

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“…1,2 In onedimensional electron systems interactions play a crucial role, giving rise to the so-called Luttinger liquid behavior. 3,4 Transport measurements are a possible method to test theoretical predictions.…”

mentioning

confidence: 99%

Transport in an inhomogeneous interacting one-dimensional system

1995

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Transport through a one-dimensional wire of interacting electrons connected to semi-infinite leads is investigated using a bosonization approach. An incident electron is transmitted as a sequence of partial charges. The dc conductance is found to be entirely determined by the properties of the leads. The dynamic nonlocal conductivity is rigorously expressed in terms of the transmission. For abrupt variations of the interaction parameters at the junctions the central wire acts as a Fabry-Perot resonator. When one of the connected wires has a tendency towards superconducting order, partial Andreev reflection of an incident electron occurs. 73.40.Jn, 74.80.Fp Typeset using REVT E X 1

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Reduction of quantized conductance at low temperatures observed in 2 to 10 μm-long quantum wires

Cited by 414 publications

References 10 publications

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Ground state structure and conductivity of quantum wires of infinite length and finite width

Transport in an inhomogeneous interacting one-dimensional system

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