Abstract
We review some of our recent experimental studies on low-carrier concentration, mesoscopic two-dimensional electron gases (m2DEGs). The m2DEGs show a range of striking characteristics including a complete avoidance of the strongly localised regime even when the electrical resistivity $\rho >> h/e^2$, giant thermoelectric response, and an apparent decoupling of charge and thermoelectric transport. We analyse the results and demonstrate that these observations can be explained based on the assumption that the charge carriers retain phase coherence over the m2DEG dimensions. Intriguingly, this would imply phase coherence on lengthscales of up to 10 $\mu$m and temperature $T$ up to 10 K which is significantly greater than conventionally expected in GaAs-based 2DEGs. Such unprecedentedly large phase coherence lengths open up several possibilities in quantum information and computation schemes.
Highlights
The two-dimensional electron gas (2DEG) has served as one of the most versatile arenas to realise and study mesoscopic systems for over three decades
We review some of our recent experimental studies on low-carrier concentration, mesoscopic two-dimensional electron gases (m2DEGs)
Mesoscopic systems are systems which are comparable in spatial extent to the electronic ‘phase-coherence’ length φ, i.e. the length over which the phase of the electron is completely randomised through inelastic processes
Summary
The two-dimensional electron gas (2DEG) has served as one of the most versatile arenas to realise and study mesoscopic systems for over three decades now. Mesoscopic systems are systems which are comparable in spatial extent to the electronic ‘phase-coherence’ length φ , i.e. the length over which the phase of the electron is completely randomised through inelastic processes These are ideal venues to study fundamental quantum effects such as localisation, but are becoming increasingly important towards the generation of quantum-based communications and information schemes which rely on the quantum nature of charge carriers. In this context, high-quality GaAs-based 2DEGs in conjunction with state-of-the-art lithographical techniques offer immense scope to create and manipulate mesoscopic structures such as onedimensional quantum wires [1,2] and zero-dimensional quantum dots [3,4]. The remainder of this Review is structured as follows: In Section 2, we describe the experimental system and the thermoelectric measurement technique, Section 3 constitutes the main body of this article where we review the experimental results, and in Section 4 we conclude with a discussion and mention of some of the outstanding issues
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
