Potential applications of quantum dots in the nanotechnology industry make these systems an important field of study in various areas of physics. In particular, thermodynamics has a significant role in technological innovations. With this in mind, we studied some thermodynamic properties in quantum dots, such as entropy and heat capacity, as a function of the magnetic field over a wide range of temperatures. The density of states plays an important role in our analyses. At low temperatures, the variation in the magnetic field induces an oscillatory behavior in all thermodynamic properties. The depopulation of subbands is the trigger for the appearance of the oscillations.
In this work we explore the use of thermodynamic length to improve the performance of experimental protocols. In particular, we implement Landauer erasure on a driven electron level in a semiconductor quantum dot, and compare the standard protocol in which the energy is increased linearly in time with the one coming from geometric optimisation. The latter is obtained by choosing a suitable metric structure, whose geodesics correspond to optimal finite-time thermodynamic protocols in the slow driving regime. We show experimentally that geodesic drivings minimise dissipation for slow protocols, …
School of Materials Science and Engineering, Ocean University of China（中国海洋大学材料科学与工程学院）；University of Shanghai for Science and Technology（上海理工大学）；South China Normal University（华南师范大学）；Sichuan University（四川大学）
Two-terminal electronic transport systems with a rectangular transmission can violate standard thermodynamic uncertainty relations. This is possible beyond the linear response regime and for parameters that are not accessible with rate equations obeying detailed-balance. Looser bounds originating from fluctuation theorem symmetries alone remain respected. We demonstrate that optimal finite-sized quantum dot chains can implement rectangular transmission functions with high accuracy and discuss the resulting violations of standard thermodynamic uncertainty relations as well as heat engine perfor…
Proposals for quantum information applications are frequently based on the coherent manipulation of spins confined to quantum dots. For these applications, p-type III-V material systems promise a reduction of the hyperfine interaction while maintaining large $g$-factors and strong spin-orbit interaction. In this work, we study bottom-gated device architectures to realize single and serial multi-quantum dot systems in Schottky contacted p-type GaSb nanowires. We find that the effect of potentials applied to gate electrodes on the nanowire is highly localized to the immediate vicinity of the gat…
We study (In,Ga)(As,Sb)/GaAs quantum dots embedded in a GaP (100) matrix, which are overgrown by a thin GaSb capping layer with variable thickness. Quantum dot samples are studied by temperature-dependent photoluminescence, and we observe that the quantum dot emission shows anomalous temperature dependence,~i.e., increase of energy with temperature increase from 10~K to $\sim$70~K, followed by energy decrease for larger temperatures. With the help of fitting of luminescence spectra by Gaussian bands with energies extracted from eight band ${\bf k}\cdot{\bf p}$ theory with multiparticle correct…
Most proof-of-principle experiments for spin qubits have been performed using GaAs-based quantum dots because of the excellent control they offer over tunneling barriers and the orbital and spin degrees of freedom. Here, we present the first realization of high-quality single and double quantum dots hosted in an InAs two-dimensional electron gas (2DEG), demonstrating accurate control down to the few-electron regime, where we observe a clear Kondo effect and singlet-triplet spin blockade. We measure an electronic $g$-factor of $16$ and a typical magnitude of the random hyperfine fields on the d…
We demonstrate a new quantum-confined semiconductor material based on GaSb quantum dots (QDs) embedded in single-crystalline AlGaSb matrix by filling droplet-etched nanoholes. The droplet-mediated growth mechanism allows formation of low QD densities required for non-classical single-QD light sources. The photoluminescence (PL) experiments reveal that the GaSb QDs have an indirect-direct bandgap crossover at telecom wavelengths. This is due to the alignment of the Γ and L valleys in the conduction band as a result of quantum confinement controlled by dimensions of the nanostructure. We show th…
Quantum dots are recognized as a suitable platform for studying thermodynamic phenomena involving single electronic charges and spins in nano-scale devices. However, such a thermodynamic system is usually driven by electron reservoirs at different temperatures, not by a lattice temperature gradient. We report on experimental observations of charge-spin cooperative dynamics in transitions of two-electron spin states in a GaAs double quantum dot located in a non-equilibrium phonon environment. Enhancements in the spin-flip processes are observed, originating from phonon excitation combined with …
