Validity of the single-particle description and charge noise resilience for multielectron quantum dots

Non-equilibrium dynamics in coupled quantum dots

The aim of this work is to study the non-equilibrium dynamics of electrons in a coupled quantum well pair. To achieve this aim, we consider a non-symmetric distribution of electrons in a double quantum well. We derive the nonlinear dynamical evolution of the carrier wave functions considering electron-phonon interactions and a time-dependent Hartree potential in multielectron quantum dots. We show the possibility of having an electrostatic trap for part of the electrons which are injected into one of the quantum wells.

Transport-induced suppression of nuclear field fluctuations in multi-quantum-dot systems

Magnetic noise from randomly fluctuating nuclear spin ensembles is the dominating source of decoherence for many multi-quantum-dot multielectron spin qubits. Here we investigate in detail the effect of a DC electric current on the coupled electron-nuclear spin dynamics in double and triple quantum dots tuned to the regime of Pauli spin blockade. We consider both systems with and without significant spin-orbit coupling and find that in all cases the flow of electrons can induce a process of dynamical nuclear spin polarization that effectively suppresses the nuclear polarization gradients over n…

Fast spin exchange between two distant quantum dots

The Heisenberg exchange interaction between neighboring quantum dots allows precise voltage control over spin dynamics, due to the ability to precisely control the overlap of orbital wavefunctions by gate electrodes. This allows the study of fundamental electronic phenomena and finds applications in quantum information processing. Although spin-based quantum circuits based on short-range exchange interactions are possible, the development of scalable, longer-range coupling schemes constitutes a critical challenge within the spin-qubit community. Approaches based on capacitative coupling and ca…

Heralded spectroscopy reveals exciton-exciton correlations in single colloidal quantum dots

Multiply-excited states in semiconductor quantum dots feature intriguing physics and play a crucial role in nanocrystal-based technologies. While photoluminescence provides a natural probe to investigate these states, room temperature single-particle spectroscopy of their emission has so far proved elusive due to the temporal and spectral overlap with emission from the singly-excited and charged states. Here we introduce biexciton heralded spectroscopy, enabled by a single-photon avalanche diode array based spectrometer. This allows us to directly observe biexciton-exciton emission cascades an…

开放二维量子点中的变分疤痕

Variational Scarring in Open Two-Dimensional Quantum Dots

本文研究开放二维量子点中的变分疤痕，证明疤痕态在开放系统中仍保持稳健，并可通过受控扰动调制电子传输，为调谐量子输运和量子器件实验实现提供新途径。

Bell-state tomography in a silicon many-electron artificial molecule

An error-corrected quantum processor will require millions of qubits, accentuating the advantage of nanoscale devices with small footprints, such as silicon quantum dots. However, as for every device with nanoscale dimensions, disorder at the atomic level is detrimental to qubit uniformity. Here we investigate two spin qubits confined in a silicon double-quantum-dot artificial molecule. Each quantum dot has a robust shell structure and, when operated at an occupancy of 5 or 13 electrons, has single spin-$\frac{1}{2}$ valence electron in its $p$- or $d$-orbital, respectively. These higher elect…

Non-Hermitian many-body topological excitations in interacting quantum dots

Quantum dots are one of the paradigmatic solid-state systems for quantum engineering, providing an outstanding tunability to explore fundamental quantum phenomena. Here we show that non-Hermitian many-body topological modes can be realized in a quantum dot chain by utilizing a gate-tunable modulation of dissipation, and they emerge purely because of the non-Hermiticity. By exactly solving the non-Hermitian interacting description both with exact diagonalization and tensor-networks, we demonstrate that these topological modes are robust even in the presence strong interactions, leading to a str…

隧穿耦合量子点非平衡电子输运中量子失谐的鲁棒性

Robustness of Quantum Discord in Nonequilibrium Electronic Transport through Tunnel-Coupled Quantum Dots

研究双量子点系统在非平衡电子输运中量子失谐的瞬态和稳态行为，发现量子失谐在宽参数范围内保持有限，且比经典关联更鲁棒。

Charge-noise tolerant exchange gates of singlet-triplet qubits in asymmetric double quantum dots

In the semi-conductor double quantum dot singlet-triplet qubit architecture, the decoherence caused by the qubit's charge environment poses a serious obstacle in the way towards large scale quantum computing. The effects of the charge decoherence can be mitigated by operating the qubit in the so called sweet spot regions where it is insensitive to electrical noise. In this paper, we propose singlet-triplet qubits based on two quantum dots of different sizes. Such asymmetric double dot systems allow the implementation of exchange gates with controllable exchange splitting $J$ operated in the do…

耦合量子点中晶体对称性保护的马约拉纳模式

Crystalline-Symmetry-Protected Majorana Modes in Coupled Quantum Dots

本文提出在耦合量子点阵列中利用π相位畴壁、闭合π结回路及满足二面体对称群Dn的Kitaev n-顶点，实现多种晶体对称性保护的马约拉纳模式，为实验探索人工拓扑晶体相提供了极简架构。