A5058772580- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Quantum Information and Cryptography
- Quantum optics and atomic interactions
- Magnetic properties of thin films
- Spectroscopy and Quantum Chemical Studies
- Quantum many-body systems
- Mechanical and Optical Resonators
- Photonic and Optical Devices
- Physics of Superconductivity and Magnetism
- Semiconductor Lasers and Optical Devices
- Quantum Mechanics and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and devices
- Tensor decomposition and applications
- Quantum Dots Synthesis And Properties
- Strong Light-Matter Interactions
- Graphene research and applications
- Random lasers and scattering media
- Quantum, superfluid, helium dynamics
- Nanowire Synthesis and Applications
- Computational Physics and Python Applications
- Laser-Matter Interactions and Applications
- Model Reduction and Neural Networks
- Quantum Computing Algorithms and Architecture
TU Dortmund University
2023-2025
Heriot-Watt University
2020-2024
University of Bayreuth
2013-2022
University of Ottawa
2018-2022
ITMO University
2022
University of Münster
2022
While several numerical techniques are available for predicting the dynamics of non-Markovian open quantum systems, most struggle with simulations very long memory and propagation times, e.g., due to superlinear scaling number time steps <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>n</a:mi></a:math>. Here, we introduce a numerically exact algorithm calculate process tensors—compact representations environmental influences—which provides advantage over previous...
The interaction of a resonant light field with quantum two-level system is key interest both for fundamental optics and technological applications employing excitation. While emission under continuous-wave excitation has been well studied, the more complex spectrum dynamically dressed states—a driven by pulsed excitation—has so far investigated in detail only theoretically. Here, we present first experimental observation complete resonance fluorescence single system, form an excitonic...
The swing up of quantum emitter population (SUPER) scheme, taking a radically different off-resonant approach to coherently excite two-level system, is explained and proposed for single-photon generation from dots.
Photon-mediated interactions between atoms can arise via coupling to a common electromagnetic mode or by quantum interference. Here, we probe the role of coherence in cooperative emission arising from two distant but indistinguishable solid-state emitters because path erasure. The primary signature emission, emergence “bunching” at zero delay an intensity correlation experiment, is used characterize indistinguishability emitters, their dephasing, and degree joint system that be coherently...
We demonstrate theoretically that the single-photon purity of photons emitted from a quantum dot exciton prepared by phonon-assisted off-resonant excitation can be significantly higher in wide range parameters than obtained resonant preparation for otherwise identical conditions. Despite excitation, brightness stays on high level. These surprising findings exploit fact is two-step process where phonons first lead to relaxation between laser-dressed states while occupations are reached only...
We characterize the coherent dynamics of a two-level quantum emitter driven by pair symmetrically-detuned phase-locked pulses. The promise dichromatic excitation is to spectrally isolate laser from emission, enabling background-free photon extraction emitter. Paradoxically, we find that not possible without spectral overlap between exciting pulse and transition for ideal systems due cancellation accumulated area. However, any additional interactions interfere with area may lead finite...
We describe a general-purpose computational toolkit for simulating open quantum systems, which provides numerically exact solutions composites of zero-dimensional systems that may be strongly coupled to multiple, quite general non-Markovian environments. It is based on process tensor matrix product operators (PT-MPOs), efficiently encapsulate environment influences. The code features implementations several PT-MPO algorithms, in particular, Automated Compression Environments (ACE)...
Abstract Semiconductor quantum dots are a versatile source of single photons with tunable properties to be used in quantum‐cryptographic applications. A crucial figure merit the emitted is photon number coherence (PNC), which impacts security many communication protocols. In process single‐photon generation, dot as solid‐state object subject an interaction phonons, can therefore indirectly affect PNC. this study, origin PNC optically excited and its phonons elaborated upon. contrast...
Process tensor matrix product operators (PT-MPOs) enable numerically exact simulations for an unprecedentedly broad range of open quantum systems. By representing environment influences in MPO form, they can be efficiently compressed using established algorithms. The dimensions inner bonds the PT-MPO may viewed as indicator complexity environment. Here, we show that themselves, not only their dimensions, have a concrete physical meaning: They represent subspace full Liouville space which...
The quantum regression theorem (QRT) is the most widely used tool for calculating multitime correlation functions assessment of emitters. It an approximate method based on a Markov assumption environmental coupling. In this Letter we quantify properties photons emitted from single dot coupled to phonons. For single-photon purity and indistinguishability, compare numerically exact path-integral results with those obtained QRT. demonstrated that QRT systematically overestimates influence...
Realizing scalable quantum networks requires a meticulous level of understanding and mitigating the deleterious effects decoherence. Many device platforms feature multiple decoherence mechanisms, often with dominant mechanism seemingly fully masking others. In this paper, we show how access to weaker dephasing mechanisms can nevertheless be obtained for optically active qubits by performing two-photon coincidence measurements. To end theoretically investigate impact different on...
The generation of photons in a microcavity coupled to laser-driven quantum dot interacting with longitudinal acoustic (LA) phonons is studied the regime simultaneously strong driving and dot-cavity coupling. stationary cavity photon number found depend non-trivial way on detuning between laser exciton transition dot. In particular, maximal efficiency feeding obtained for detunings corresponding energies cavity-dressed states excitation numbers larger than one. Phonons significantly enhance...
We report on simulations of the degree polarization entanglement photon pairs simultaneously emitted from a quantum dot-cavity system that demand revisiting role phonons. Since coherence is fundamental precondition for and phonons are known to be major source decoherence, it seems unavoidable can only degrade entanglement. In contrast, we demonstrate cause even surpasses corresponding value phonon-free case. particular, consider situation comparatively small biexciton binding energies either...
We present here an atomistic theory of the electronic and optical properties hexagonal InAsP quantum dots in InP nanowires wurtzite phase. These self-assembled are unique that their heights, shapes, diameters well known. Using a combined valence-force-field, tight-binding, configuration-interaction approach we perform calculations single-particle states excitonic, biexcitonic trion complexes as emission spectra function dot height, diameter As versus P concentration. The tight-binding...
The trion, a quasiparticle comprising one exciton and an additional charge carrier, offers unique opportunities for generating spin-photon interfaces that can be used in developing quantum networks. Trions are also actively sought after integrated optoelectronic devices including photovoltaics, photodetectors, spintronics. However, formation of trions strongly confined low-dimensional materials is often deemed detrimental. This because trion emission such typically prohibited due to the...
Indistinguishable quantum emitters confined to length scales smaller than the wavelength of light become superradiant. Compared uncorrelated and distinguishable emitters, superradiance results in qualitative modifications optical signals such as photon coincidences. However, recent experiments revealed that similar signatures can also be obtained situations where are too far separated superradiant if correlations between induced by wave-function collapse during an emission-angle-selective...
The memory induced by the environment is of utmost importance for many few-level quantum systems in condensed matter. Here, authors show how a real-time path-integral approach can be used to calculate nonequilibrium multitime correlation functions open without any approximation model, dealing consistently with non-Markovian and Markovian reservoirs. This method avoids using regression theorem that not valid when matters. illustrate new scheme calculating emission spectrum dot second-order...
We compare three different notions of concurrence to measure the polarization entanglement two-photon states generated by biexciton cascade in a quantum dot embedded microcavity. focus on often-discussed situation with finite binding energy cavity tuned resonance. Apart from time-dependent concurrence, which can be assigned density matrix at any point time, we study single- and double-time integrated concurrences commonly used literature that are based state reconstruction schemes. argue...
Abstract Semiconductor quantum rings are topological structures that support fascinating phenomena such as the Aharonov–Bohm effect and persistent current, which of high relevance in research information devices. The annular shape distinguishes them from other low-dimensional materials, enables topologically induced properties geometry-dependent spin manipulation emission. While optical transition dipole moments (TDMs) zero to two-dimensional emitters have been well investigated, those...
The on-demand preparation of higher-order Fock states is fundamental importance in quantum information sciences. We propose and compare different protocols to generate solid state quantum-dot–cavity systems. make use a series laser pulses excite the dot exciton off-resonant control detuning between cavity. Our theoretical studies include cavity loss processes as well pure-dephasing type coupling longitudinal acoustic phonons numerically complete fashion. By going beyond two-level...
Semiconductor quantum dots have emerged as an especially promising platform for the generation of polarization-entangled photon pairs. However, it was demonstrated recently that two-photon excitation scheme employed in state-of-the-art experiments limits achievable degree entanglement by introducing which-path information. In this work, combined impact and longitudinal acoustic phonons on pairs emitted strongly-confining is investigated. It found further reduce even limit vanishing...
Cooperative effects of multiple quantum emitters are characterized by transitions via delocalized collective states with altered emission properties due to the existence interemitter coherences. When realized excitonic condensed-matter nanostructures, these significantly affected presence strong emitter-phonon coupling, which leads formation polarons. We show that, while for single-emitter into free space this has no impact on its radiative lifetime, same is not true superradiant emission....
The algorithm “automated compression of environments” (ACE) [M. Cygorek , ] provides a versatile way simulating an extremely broad class open quantum systems. This is achieved by encapsulating the influence environment, which determined interaction Hamiltonian(s) and initial states, into compact process tensor matrix product operator (PT-MPO) representations. generality ACE method comes at high numerical cost. Here, we demonstrate that orders-of-magnitude improvement possible changing order...