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Showing 1 to 15 of 15 for “"quantum point contact"”.
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The scaling behavior of the entanglement entropy in 2+1 dimensional critical systems
… 2+1 dimensional critical systems, the conformal quantum critical theories, has a universal subleading correction that likewise gives information about the underlying critical system. In addition, I address the issue of whether the dynamical entanglement entropy, the entanglement generated by a …
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Microwave Spectroscopy and Transport Measurements of Andreev Bound States in Superconductor – Semiconductor Josephson Junctions
… is governed by a combination of the macroscopic quantum coherence of superconducting systems and the mesoscopic physics inherent to semiconducting devices and Andreev bound states are the microscopic states which mediate transport through these junctions. In this thesis a series of experiments …
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Tunable spin polarization and conductance anomalies in mesoscopic one-dimensional systems
… – for instance, the “0.7” conductance anomaly in quantum point contacts – have remained unexplained. In this dissertation, we present a comprehensive theoretical model for electronic transport in quasi-1D systems, accounting for many-body effects and neglecting spin–orbit couplings. Then, with …
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Thermoelectric properties of mesoscopic systems in GaAs
… (2DMSs) and antidot lattices defined in them. Quantum oscillations in the thermopower (TP) of a quantum point contact allow accurate determination of the local electron temperature. The low temperature (T < 0.3 K) TP of square (5 ?m x 5 ?m) mesoscopic devices shows a highly enhanced value, …
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Quantum transport in graphene nanotransistors
… the role of lattice geometry, such as a quantum point contact constriction, on their performance. We perform a demonstration of the ability to detect the passage of double and single-stranded DNA, through molecular dynamics simulations. The transistors presented are capable of sensing the …
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Electron tunneling and spin relaxation in a lateral quantum dot
… sensing to probe a single-electron lateral quantum dot. The charge sensor is a quantum point contact (QPC) adjacent to the dot and the sensitivity is comparable to other QPC-based systems. We develop an automated feedback system to position the energies of the states in the dot with respect …
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Spin Properties of Heavy Holes in Low-Dimensional Quantum Electronic Devices
The rich spin physics in quantum confined holes has attracted significant ongoing research interest for over 20 years. The ability to manipulate the spin degrees of freedom in spin-orbit coupled holes via an electric field has opened up the field of spin-based electronics, or spintronics. In this …
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Using multiplexers to study the statistics of quantum phenomenon in one-dimensional wires
The quantum point contact (QPC) is a one-dimensional constriction with the differential conductance quantised in units of $G_Q=2e^2/h$. However, the transport behaviour below the first plateau is still not fully understood, including the 0.7 anomaly and the 0.25 anomaly in the linear and non-linear …
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Edge tunneling and transport in non-abelian fractional quantum Hall systems
… aspects of tunneling at the edge of a fractional quantum Hall (FQH) state are studied. Most examples are given for the non- abelian filling fraction ? = 5 2 Moore-Read Pfaffian state. For tunneling between opposite edges of an abelian fractional quantum Hall state at a quantum point contact, the …
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Electronic and Spin Correlations in Asymmetric Quantum Point Contacts
<p>A quantum point contact (QPC) is a quasi-one dimensional electron system, for which the conductance is quantized in unit of $2e^2/h$. This conductance quantization can be explained in a simple single particle picture, where the electron density of states cancels the electron velocity to a …
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Charge detection in semiconductor nanostructures
… in two solid state systems: Lateral GaAs quantum dots and hydrogenated amorphous silicon (a-Si:H). In both of these experiments we use time-resolved charge sensing to study electron transport in regimes that are not accessible to traditional transport measurements. For the lateral GaAs …
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Engineering superconductivity in ballistic semiconductor nanowires
… are promising materials for studying novel quantum devices. Following proposals to use 1D nanostructure to realize Majorana zero modes, quasiparticles that are relevant for topological quantum computing, many groups have attempted to engineer these modes in hybrid …
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Bandstructure calculations for holes in GaAs and simulations of dc conductance in electron quantum point contacts
… We simulated data for a parabolic QPC saddle-point potential at T=0 K and analyse the data using methods based on the AC conductance and on the DC conductance. We show that the two methods are compatible and accurate to ±4 % for the ideal simulated data set, which is free of experimental …
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Surface-acoustic-wave-defined dynamic quantum dots
… channel creates a series of dynamic quantum dots which can transport electrons at the SAW velocity (∼ 2800 ms−1 ), allowing high-frequency operations to be carried out on the electron without the need for fast pulsed-gate techniques. Such dynamic quantum dot devices can provide …
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Experimental Realisation of Energy Harvesters built from Quantum Dots and Quantum Wells
… harvester built from two resonant-tunnelling quantum dots. A device, proposed by Jordan et al. [1], harvests energy from an area of 90 μ m2 of a two-dimensional electron gas (2DEG), using the energy-selective transport of electrons through a pair of quantum dots. It has proven to be an …