A5081730191- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Quantum Mechanics and Applications
- Topological Materials and Phenomena
- Neural Networks and Reservoir Computing
- Surface and Thin Film Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Thermodynamics and Statistical Mechanics
- Quantum, superfluid, helium dynamics
- Superconducting Materials and Applications
- Advanced Electrical Measurement Techniques
- Microwave and Dielectric Measurement Techniques
- Sensor Technology and Measurement Systems
- Electronic and Structural Properties of Oxides
- Analytical Chemistry and Sensors
- Advanced Theoretical and Applied Studies in Material Sciences and Geometry
- Extraction and Separation Processes
- Advanced Condensed Matter Physics
- Atomic and Subatomic Physics Research
- Quantum optics and atomic interactions
- Structural mechanics and materials
- Strong Light-Matter Interactions
- Chemical and Physical Properties in Aqueous Solutions
Microsoft Research (United Kingdom)
2021
University of Copenhagen
2019-2021
Microsoft (Denmark)
2019-2021
Universität Innsbruck
2013-2020
Institute for Quantum Optics and Quantum Information Innsbruck
2013
Austrian Academy of Sciences
2013
University of Buenos Aires
2010
University of Concepción
2000-2001
Quantum computers are able to outperform classical algorithms. This was long recognized by the visionary Richard Feynman who pointed out in 1980s that quantum mechanical problems were better solved with machines. It only 1994 Peter Shor came up an algorithm is calculate prime factors of a large number vastly more efficiently than known possible computer. paradigmatic stimulated flourishing research information processing and quest for actual implementation Over last fifteen years, using...
Fault-tolerant quantum computing Quantum states can be delicate. Attempts to process and manipulate destroy the encoded information. Nigg et al. state of a single qubit (in this case, trapped ion) over global properties series ions. These so-called stabilizers protected information against noise sources that degrade qubit. The protocol provides route fault-tolerant computing. Science , issue p. 302
Quantum computers promise to solve certain problems more efficiently than their digital counterparts. A major challenge towards practically useful quantum computing is characterizing and reducing the various errors that accumulate during an algorithm running on large-scale processors. Current characterization techniques are unable adequately account for exponentially large set of potential errors, including cross-talk other correlated noise sources. Here we develop cycle benchmarking, a...
Quantum computers hold the promise to solve certain problems exponentially faster than their classical counterparts. Trapped atomic ions are among physical systems in which building such a computing device seems viable. In this work we present small-scale quantum information processor based on string of 40Ca+ confined macroscopic linear Paul trap. We review our set operations includes non-coherent allowing us realize arbitrary Markovian processes. order build larger it is mandatory reduce...
Lattice gauge theories describe fundamental phenomena in nature, but calculating their real-time dynamics on classical computers is notoriously difficult. In a recent publication [Nature 534, 516 (2016)], we proposed and experimentally demonstrated digital quantum simulation of the paradigmatic Schwinger model, U(1)-Wilson lattice theory describing interplay between fermionic matter bosons. Here, provide detailed theoretical analysis performance potential this protocol. Our strategy based...
Measurement-based quantum computation represents a powerful and flexible framework for information processing, based on the notion of entangled states as computational resources. The most prominent application is one-way computer, with cluster state its universal resource. Here we demonstrate principles measurement-based using deterministically generated states, in system trapped calcium ions. First implement set operations computing. Second family error correction codes show their improved...
We present conductance-matrix measurements of a three-terminal superconductor-semiconductor hybrid device consisting two normal leads and one superconducting lead. Using symmetry decomposition the conductance, we find that antisymmetric components pairs local nonlocal conductances qualitatively match at energies below gap, compare this finding with relations based on noninteracting scattering matrix approach. Further, charge character Andreev bound states is extracted from...
We analyze the evolution of quantum state networks oscillators coupled with arbitrary external environments. show that reduced density matrix network always obeys a local master equation simple analytical solution. use this to study emergence thermodynamical laws in long time regime demonstrating two main results: First, we it is impossible build absorption refrigerator using linear (thus, nonlinearity an essential resource for such refrigerators recently studied by Levy and Kosloff [Phys....
Conclusively identifying Majorana modes in nanowires is an long-standing experimental challenge. Within the field, consensus emerging that achieving this goal will require measurements on three-terminal devices. Here, authors report some of first results such devices using nonlocal conductance. They find zero-bias peaks are preceded by closure bulk gap, which indicates these associated with properties nanowire. However, behavior device after gap suggests disorder remains important limitation.
End-to-end correlated bound states are investigated in superconductor-semiconductor hybrid nanowires at zero magnetic field. Peaks subgap conductance independently identified from each wire end, and a cross-correlation function is computed that counts end-to-end coincidences, averaging over thousands of features. Strong correlations short, 300-nm device reduced by factor 4 long, 900-nm device. In addition, distributions investigated, between the left right based on their mutual information.
Quantum algorithms require a universal set of gates that can be implemented in physical system. For these, an optimal decomposition into sequence available operations is desired. Here, we present method to find such sequences for small-scale ion trap quantum information processor. We further adapt the state preparation and with in-sequence measurements.
We develop a protocol to determine the presence and extent of topological phase with Majorana zero modes in hybrid superconductor-semiconductor device. The is based on conductance measurements three-terminal device two normal leads one superconducting lead. A radio-frequency technique acts as proxy for measurement local conductance, allowing rapid, systematic scan large experimental space cause bias peaks at each end wire, so we identify promising regions by filtering this condition. To...
A century on from the development of quantum theory, interpretation a state is still discussed. If physicist claims to have produced system with particular wave function, does this represent directly physical some kind, or function merely summary knowledge, information, about system? recent no-go theorem shows that models in which not physical, but corresponds only an experimenter's information hypothetical real system, must make different predictions theory when certain test carried out....
We study the thermodynamical properties of crystals trapped ions which are laser cooled to two different temperatures in separate regions. show that these strongly depend on structure ion crystal. Such can be changed by varying trap parameters and undergoes a series phase transitions from linear zig-zag or helicoidal configurations. Thus, we systems ideal candidates observe control transition anomalous normal heat transport. All structures behave as 'heat superconductors', with thermal...
We describe, realize, and experimentally investigate a method to perform physical rotations of ion chains, trapped in segmented surface Paul trap, as building block for large-scale quantum computational sequences. Control trapping potentials is achieved by parametrizing electrode voltages terms spherical harmonic potentials. Voltage sequences that enable crystal are numerically obtained optimizing time-dependent positions motional frequencies, taking into account the effect electrical...
Abstract Poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid), poly(methacrylic and five copolymers of poly[(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐ co ‐(methacrylic acid)] were synthesized by radical polymerization obtained in yields >97%. The polymers characterized FT‐IR, [ 1 H]NMR, 13 C]NMR studied means the Liquid‐phase Polymer‐based Retention (LPR) technique. metal ion retention ability for Cu(II), Cd(II), Co(II), Hg(II), Ni(II), Zn(II), Cr(III) Ag(I) was investigated at...
In general, a quantum measurement yields an undetermined answer and alters the system to be consistent with result. This process maps multiple initial states into single state thus cannot reversed. has important implications in information processing, where errors can interpreted as measurements. Therefore, it seems that is impossible correct processor, but protocols exist are capable of eliminating them if they affect only part system. this work we present deterministic reversal fully...
Performing experiments on small-scale quantum computers is certainly a challenging endeavor. Many parameters need to be optimized achieve high-fidelity operations. This can done efficiently for operations acting single qubits as errors fully characterized. For multi-qubit operations, though, this no longer the case in most general analyzing effect of operation system requires full state tomography which resources scale exponentially with size. Furthermore, recent additional electronic levels...
Se han sintetizado tres copolimeros a partir de los monomeros acido 2-acrilamida-2-metil-1-propansulfonico y metacrilico. analizado las interacciones en funcion del pH estos correspondientes homopolimeros con iones metalicos Cu2+, Cd2+, Co2+, Cr3+, Zn2+, Ni2+ Ag+, utilizando la tecnica ultrafiltracion. Los polimeros muestran un comportamiento tipico polielectrolitos.
In this article we study measurement circuit effects in three-terminal electrical transport measurements arising from finite line impedances. We provide exact expressions relating the measured voltages and differential conductances to their values at device under test, which allow for spurious voltage divider be corrected. Finally, test implementation of these corrections with experimental measurements.