Doping of semiconductors by impurity atoms enabled their widespread technological application in microelectronics and optoelectronics. However, doping has proven elusive for strongly confined colloidal semiconductor nanocrystals because the synthetic challenge how to introduce single impurities, as well a lack fundamental understanding this heavily doped limit under strong quantum confinement. We developed method dope with metal enabling control band gap Fermi energy. A combination optical...

We study the infinite temperature dynamics of a prototypical one-dimensional system expected to exhibit many-body localization. Using numerically exact methods, we establish dynamical phase diagram this based on statistics its eigenvalues and behavior. show that nonergodic is reentrant as function interaction strength, illustrating localization can be reinforced by sufficiently strong interactions even at temperature. Surprisingly, within accessible time range, ergodic shows subdiffusive...

Current nonequilibrium Monte Carlo methods suffer from a dynamical sign problem that makes simulating real-time dynamics for long times exponentially hard. We propose new `Inchworm Algorithm', based on iteratively reusing information obtained in previous steps to extend the propagation longer times. The algorithm largely overcomes problem, changing scaling exponential quadratic. use method solve Anderson impurity model Kondo and mixed valence regimes, obtaining results both quenches spin...

Memory effects play a key role in the dynamics of strongly correlated systems driven out equilibrium. In present study, we explore nature memory nonequilibrium Anderson impurity model. The Nakajima--Zwanzig--Mori formalism is used to derive an exact generalized quantum master equation for reduced density matrix interacting dot, which includes non-Markovian kernel. A real-time path integral formulation developed, all diagrams are stochastically sampled order numerically evaluate We...

We investigate the dynamical and steady-state spin response of nonequilibrium Anderson model to magnetic fields, bias voltage, temperature using a numerically exact method combining bold-line quantum Monte Carlo technique with memory function formalism. obtain converged results in range previously inaccessible regimes, particular calculating dynamics for temperatures down crossover Kondo domain. provide predictions phenomena, including nonmonotonic dependence observables at high voltage...

Electrostatic force microscopy is used to study light-induced charging in single hybrid Au-CdSe nanodumbbells. Upon illumination, nanodumbbells show negative charging, which contrast with CdSe rods and Au particles that positive charging. This different behavior attributed charge separation the nanodumbbells, where after excitation electron transferred gold tips hole subsequently filled through tunneling interactions substrate. The process of at metal-semiconductor interface key for...

The interplay between interference effects and electron-electron interactions in electron transport through an interacting double quantum dot system is investigated using a hierarchical master equation approach which becomes exact if carried to infinite order converges well the temperature not too low. Decoherence due found give rise pronounced negative differential resistance, enhanced broadening of structures current-voltage characteristics, inversion electronic population. Dependence on...

The nonequilibrium spectral properties of the Anderson impurity model with a chemical potential bias are investigated within numerically exact real-time quantum Monte Carlo formalism. two-time correlation function is computed in form suitable for dynamical mean field calculations. Additionally, evolution model's simulated an alternative representation, defined by hypothetical but experimentally realizable weakly coupled auxiliary lead. voltage splitting Kondo peak confirmed and dynamics its...

We present a numerically exact steady-state inchworm Monte Carlo method for nonequilibrium quantum impurity models. Rather than propagating an initial state to long times, the is directly formulated in steady state. This eliminates any need traverse transient dynamics and grants access much larger range of parameter regimes at vastly reduced computational costs. benchmark on equilibrium Green's functions dots noninteracting limit unitary Kondo regime. then consider correlated materials...

We investigate the real-time dynamics of sub-Ohmic spin-boson model across a broad range coupling strengths, using numerically exact inchworm quantum Monte Carlo algorithm. From short- and intermediate-time starting from an initially decoupled state, we extract signatures zero-temperature phase transition between localized delocalized states. show that dynamical diagram thus obtained differs equilibrium in both values critical couplings associated exponent. also identify quantitatively...

The existence of more than one steady state in a many-body quantum system driven out equilibrium has been matter debate, both the context simple impurity models and case inelastic tunneling channels. In this paper, we combine reduced density matrix formalism with multilayer multiconfiguration time-dependent Hartree method to address problem. This allows us obtain converged numerical solution nonequilibrium dynamics. Considering generic model for transport through dot electron-phonon...

We give a detailed comparison of the hierarchical quantum master equation (HQME) method to continuous-time Monte Carlo (CT-QMC) approach, assessing usability these numerically exact schemes as impurity solvers in practical nonequilibrium calculations. review main characteristics methods and discuss scaling associated numerical effort. substantiate our discussion with explicit results for transport properties single-site Anderson impurity. The effort HQME scheme scales linearly simulation...

We present two methods for computing two-time correlation functions or Green's from real-time bold-line continuous-time quantum Monte Carlo. One method is a formally exact generalized auxiliary lead formalism by which spectral properties may be obtained single-time observables. The other involves the evaluation of diagrams contributing to observables directly on Keldysh contour. Additionally, we provide detailed description Carlo method. Our are general and numerically exact, able reliably...

The time-dependent full counting statistics of charge transport through an interacting quantum junction is evaluated from its generating function, controllably computed with the inchworm Monte Carlo method. Exact noninteracting results are reproduced; then, we continue to explore effect electron-electron interactions on cumulants, first-passage time distributions, and $n$-electron transfer distributions. We observe a crossover in noise Coulomb blockade Kondo-dominated physics as temperature...

We present a brief pedagogical review of theoretical Green's function methods applicable to open quantum systems out equilibrium, in general, and single molecule junctions, particular. briefly describe experimental advances molecular electronics then discuss different approaches. focus on methods. Two characteristic energy scales governing the physics are many-body interactions within junctions molecule–contact coupling. We, therefore, weak coupling as two limits that can be conveniently...

The simulation of strongly correlated quantum impurity models is a significant challenge in modern condensed matter physics that has multiple important applications. Thus far, the most successful methods for approaching this involve Monte Carlo techniques accurately and reliably sample perturbative expansions to any order. However, cost obtaining high precision through these high. Recently, tensor train decomposition have been developed as an alternative integration. In study, we apply...

A description of long-lived photodoped states in Mott insulators is challenging, as it needs to address exponentially separated timescales. We demonstrate how properties such can be computed using numerically exact steady state techniques, particular, the quantum Monte Carlo algorithm, by a time-local ansatz for distribution function with separate Fermi functions electron and hole quasiparticles. The simulations show that gap remains robust large photodoping, has quasiparticles strongly...

We present an algorithm for reconstructing a sample surface potential from its Kelvin probe force microscopy (KPFM) image. The measured KPFM image is weighted average of the underneath tip apex due to long-range electrostatic forces. model measurement by linear shift-invariant system where impulse response point spread function (PSF). By calculating PSF (tip+cantilever) and using noise statistics, we deconvolve obtain sample.The reconstruction applied measurements CdS-PbS nanorods in...

The reduced dynamics formalism has recently emerged as a powerful tool to study the of non-equilibrium quantum impurity models in strongly correlated regimes. Examples include Anderson model near Kondo crossover temperature and Holstein model, for which provides an accurate description density matrix system wide range timescales. In this work, we generalize allow non-system observables such current between leads. We show that equation motion observable interest can be closed with demonstrate...

In this second paper of a two part series, we present extensive benchmark results for different inchworm Monte Carlo expansions the spin–boson model. Our are compared to previously developed numerically exact approaches problem. A detailed discussion convergence and error propagation is presented. analysis allow an understanding benefits drawbacks other real-time non-adiabatic quantum dynamics.

We generalize the recently developed inchworm quantum Monte Carlo method to full Keldysh contour with forward, backward, and equilibrium branches describe dynamics of strongly correlated impurity problems time-dependent parameters. introduce a compute Green's functions, spectral currents for show how systematic error assessments in real time can be obtained. then illustrate capabilities algorithm study behavior impurities after an instantaneous voltage quench from thermal state.

We analyze the time-dependent formation of spectral function an Anderson impurity model in Kondo regime within a numerically exact real-time quantum Monte Carlo framework. At steady state, splitting peak occurs with nontrivial dependence on voltage and temperature, little effect location or intensity high-energy features. Examining transient development after quench from initially uncorrelated state reveals two-stage process where initial single central is followed by splitting. time detail...

Dynamical mean field theory allows access to the physics of strongly correlated materials with nontrivial orbital structure, but relies on ability solve auxiliary multiorbital impurity problems. The most successful approaches date for solving these problems are various continuous time quantum Monte Carlo algorithms. Here, we consider perhaps simplest realization physics: bilayer Hubbard model an infinite-coordination Bethe lattice. Despite its simplicity, majority this model's phase diagram...

Spin-1/2 electrons are scattered through one or two diamond-like loops, made of quantum dots connected by one-dimensional wires, and subject to both an Aharonov--Bohm flux (Rashba Dresselhaus) spin-orbit interactions. With some symmetry between the branches each diamond, with appropriate tuning electric magnetic fields (or diamond shapes), this device completely blocks polarization allows only opposite be transmitted. The directions these polarizations tunable fields, do not depend on energy...

The dynamical interplay between electron-electron interactions and electron-phonon coupling is investigated within the Anderson-Holstein model, a minimal model for open quantum systems that embody these effects. influence of phonons on spectral transport properties explored in equilibrium, non-equilibrium steady state transient dynamics after quench. Both particle-hole symmetric more generic asymmetric cases are studied. treatment based two complementary non-crossing approximations, first...