A5079762418- Quantum Information and Cryptography
- Photonic and Optical Devices
- Neural Networks and Reservoir Computing
- Plasmonic and Surface Plasmon Research
- Quantum Computing Algorithms and Architecture
- Mechanical and Optical Resonators
- Optical Network Technologies
- Gold and Silver Nanoparticles Synthesis and Applications
- Advanced Fiber Laser Technologies
- Orbital Angular Momentum in Optics
- Laser-Matter Interactions and Applications
- Quantum optics and atomic interactions
- Electrocatalysts for Energy Conversion
- Advancements in Semiconductor Devices and Circuit Design
- Quantum-Dot Cellular Automata
- Advanced battery technologies research
- Quantum Mechanics and Applications
- Nonlinear Optical Materials Studies
- Electron and X-Ray Spectroscopy Techniques
- Advanced Fluorescence Microscopy Techniques
- Strong Light-Matter Interactions
- Quantum and electron transport phenomena
- Magnetic Properties and Synthesis of Ferrites
- Electrochemical Analysis and Applications
- X-ray Spectroscopy and Fluorescence Analysis
University of Vienna
2014-2023
Vienna Center for Quantum Science and Technology
2018-2023
Helmholtz-Zentrum Berlin für Materialien und Energie
2015-2019
In a quantum computer, creating superpositions of bits (qubits) in different states can lead to speed-up over classical computers [1], but mechanics also allows for the superposition circuits [2]. fact, it has recently been theoretically predicted that superimposing circuits, each with gate order, could provide an even further computational advantage [3-5]. Here, we experimentally demonstrate this enhancement by applying two gates both possible orders determine whether commute or...
Abstract Among the various approaches to quantum computing, all-optical architectures are especially promising due robustness and mobility of single photons. However, creation two-photon logic gates required for universal computing remains a challenge. Here we propose two-qubit gate, where qubits encoded in surface plasmons graphene nanostructures, that exploits graphene's strong third-order nonlinearity long plasmon lifetimes enable single-photon-level interactions. In particular, utilize...
We investigate high-harmonic generation in graphene heterostructures consisting of metallic nanoribbons separated from a sheet by either few-nanometer layer aluminum oxide or an atomic monolayer hexagonal boron nitride. The amplify the near-field at relative to externally applied pumping, thus allowing us observe third- and fifth-harmonic carbon modest pump powers mid-infrared. study dependence nonlinear signals on ribbon width spacer thickness, as well power polarization, demonstrate...
Interference between two waves is a well-known concept in physics, and its generalization to more than straightforward. The order of interference defined as the number paths that interfere manner cannot be reduced patterns lower order. In practice, second-order means in, say, triple-slit experiment, pattern when all three slits are open can predicted from possible pairs slits. Quantum mechanics often said only exhibit interference. However, this true under specific assumptions, typically...
Multi-photon state generation is of great interest for near-future quantum simulation and computation experiments.To-date spontaneous parametric down-conversion still the most promising process, even though two major impediments exist: accidental photon noise (caused by probabilistic non-linear process) imperfect single-photon purity (arising from spectral entanglement between pairs).In this work, we overcome both these difficulties (1) exploiting a passive temporal multiplexing scheme (2)...
Abstract In standard communication information is carried by particles or waves. Counterintuitively, in counterfactual and can travel opposite directions. The quantum Zeno effect allows Bob to transmit a message Alice encoding he never interacts with. A first remarkable protocol for relied on thousands of ideal optical operations high success rate performance. Experimental realizations that have thus employed post-selection demonstrate counterfactuality. This post-selection, together with...
Both photonic quantum computation and the establishment of a internet require fiber-based measurement feed-forward in order to be compatible with existing infrastructure. Here we present fiber-compatible scheme for feed-forward, whose performance is benchmarked by carrying out remote preparation single-photon polarization states at telecom-wavelengths. The result projective on one photon deterministically controls path second takes ultrafast optical switches. By placing well-calibrated bulk...
Quantum computers are on the brink of surpassing capabilities even most powerful classical computers. This naturally raises question how one can trust results a quantum computer when they cannot be compared to simulation. Here we present verification technique that exploits principles measurement-based computation link circuits different input size, depth, and structure. Our approach enables consistency checks computations within device, as well between independent devices. We showcase our...
Multifrequency electron paramagnetic resonance (EPR, 9.4 and 263 GHz) X-ray absorption spectroscopy (XAS) were employed to study structural electrochemical changes of selected Mn complexes in contact with dried Nafion films upon electro-oxidation after long-term illumination. It was found that when the Mn-Me3TACN are reduced into Mn(II) an octahedral geometry (Me3TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane). The reduction process involves intermediate product which has been from initial...
Accidental photon noise and imperfect single-photon purity in spontaneous parametric down-conversion (SPDC) at telecom wavelengths are overcome by exploiting a passive temporal multiplexing scheme optimizing the spectral properties of down- converted photons.
Electronic structure modifications due to strain are an effective method for tailoring nano-scale functional materials. Demonstrated on nickel oxide (NiO) thin films, Resonant Inelastic X-ray Scattering (RIXS) at the transition-metal M2,3-edge is shown be a powerful tool measuring electronic modification in near-surface region. Analyses from RIXS comparison with dedicated crystal field multiplet calculations show distortions 40 nm NiO grown magnesium (MgO) substrate (NiO/MgO) similar those...
In counterfactual communication particles and information can travel in opposite directions. With our high-fidelity programmable nanophotonic processor we implement the first trace-free protocol without post-selection with a violation as low 2.4%.
An amendment to this paper has been published and can be accessed via a link at the top of paper.
Today's intermediate-scale quantum devices are on the brink of outperforming their classical counterparts. Yet these remain noisy, and with no trusted computers to check results, we left a dire need verify that they indeed perform as intended. The standard approach this problem is benchmark performance individual building blocks using techniques such process tomography or randomized benchmarking then extrapolate full system. In practice, however, an extrapolation can be unreliable due...
In contrast to standard communication, counterfactual communication (CFC) counterintuitively allows information exchange without particle exchange. this paper we use advances in integrated photonics implement a CFC protocol that does not rely on post-selection.
Graphene-metal heterostructures can confine the optical field down to atomic level. We report record enhancement of high-harmonic generation and demonstrate, for first time, that plasmons indeed affect graphene nonlinear response.
The ability to concentrate light into nanometric volumes enables access an ultrastrong light-matter coupling regime. Graphene-based platforms are extremely appealing for achieving this goal. Indeed, unique 2D material possesses a strong third-order nonlinear response, which, thanks the intense near-fields associated with excitation of surface plasmons, can be made substantial even at single-photon level [1] , [2] .
In sufficiently thin nonlinear materials, the phase-matching condition of four-wave mixing relaxes. We characterize resulting broadband biphoton states by stimulated emission tomography, and present progress towards photon pair generation in ultra-thin carbon nanotube films.
Interference between two waves is a well-known concept in physics, and its generalization to more than straight-forward. The order of interference defined as the number paths that interfere manner cannot be reduced patterns lower order. In practice, second-order means in, say, triple-slit experiment, pattern when all three slits are open can predicted from possible pairs slits. Quantum mechanics often said only exhibit interference. However, this true under specific assumptions, typically...
The scalability of photonic quantum-computation is limited by the low success probability two-qubit logic gates. We propose a root-SWAP gate based on graphene nanoribbons, where strong two-plasmon absorption boosts its above 90%.
Graphene's strong third-order nonlinearity could allow single-photon level interactions. Using third-harmonic generation, we characterize this over a wide wavelength range (1-4um). We study further plasmon enhancement by resonantly pumping graphene nanoribbons.