A5019018184- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Mechanical and Optical Resonators
- Quantum Computing Algorithms and Architecture
- Quantum optics and atomic interactions
- Photonic and Optical Devices
- Quantum Mechanics and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Physics of Superconductivity and Magnetism
- Advanced Fiber Laser Technologies
- Atomic and Subatomic Physics Research
- Laser-Matter Interactions and Applications
- Neural Networks and Reservoir Computing
- Magneto-Optical Properties and Applications
- Strong Light-Matter Interactions
- Advanced MEMS and NEMS Technologies
- Atomic and Molecular Physics
- Advanced Frequency and Time Standards
- Advanced Thermodynamics and Statistical Mechanics
- Force Microscopy Techniques and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Optical Sensing Technologies
- Optical Network Technologies
- Advanced Chemical Physics Studies
- Quantum-Dot Cellular Automata
Universität Innsbruck
2013-2025
Austrian Academy of Sciences
2014-2025
Institute for Quantum Optics and Quantum Information Innsbruck
2008-2021
Vorarlberg University of Applied Sciences
2017
Yale University
2011-2015
University of New Haven
2014
Superconducting quantum circuits based on Josephson junctions have made rapid progress in demonstrating behavior and scalability. However, the future prospects ultimately depend upon intrinsic coherence of junctions, whether superconducting qubits can be adequately isolated from their environment. We introduce a new architecture for employing three-dimensional resonator that suppresses qubit decoherence while maintaining sufficient coupling to control signal. With architecture, we...
A series of trapped calcium ions was used to simulate the complex dynamics an interacting spin system.
In contrast to a single quantum bit, an oscillator can store multiple excitations and coherences provided one has the ability generate manipulate complex multiphoton states. We demonstrate control by using superconducting transmon qubit coupled waveguide cavity resonator with highly ideal off-resonant coupling. This dispersive interaction is much greater than decoherence rates higher-order nonlinearities allow simultaneous manipulation of hundreds photons. With tool set conditional...
We experimentally demonstrate a quantum walk on line in phase space using one and two trapped ion. A with up to 23 steps is realized by subjecting an ion state-dependent displacement operations interleaved coin tossing operations. To analyze the ion's motional state after each step we apply technique that directly maps probability density distribution onto internal state. The measured distributions position's second moment clearly show non-classical character of walk. further highlight...
We present a semiclassical method for determining the effective low-energy quantum Hamiltonian of weakly anharmonic superconducting circuits containing mesoscopic Josephson junctions coupled to electromagnetic environments made an arbitrary combination distributed and lumped elements. A convenient basis, capturing multimode physics, is given by quantized eigenmodes linearized circuit fully determined classical linear response function. The used calculate numerically spectrum 3D transmon...
We propose to encode a quantum bit of information in superposition coherent states an oscillator, with four different phases. Our encoding single cavity mode, together protection protocol, significantly reduces the error rate due photon loss. This is ensured by efficient correction scheme employing nonlinearity provided physical qubit coupled cavity. describe detail how implement these operations circuit electrodynamics system. proposal directly addresses task building hardware-efficient...
We report on quantum simulations of relativistic scattering dynamics using trapped ions. The simulated state a particle is encoded in both the electronic and vibrational an ion, representing discrete continuous components wave functions. Multiple laser fields auxiliary ion simulate generated by Dirac equation presence potential. Measurement reconstruction packet enables frame-by-frame visualization processes. By precisely engineering range external potentials we are able to text book...
We report on the first absolute transition frequency measurement at ${10}^{\ensuremath{-}15}$ level with a single, laser-cooled $^{40}\mathrm{Ca}^{+}$ ion in linear Paul trap. For this measurement, comb is referenced to transportable Cs atomic fountain clock of LNE-SYRTE and used measure $4s\text{ }^{2}S_{1/2}\ensuremath{-}3d\text{ }^{2}D_{5/2}$ electric-quadrupole frequency. After correction systematic shifts, ${\ensuremath{\nu}}_{{\mathrm{Ca}}^{+}}=411\text{ }042\text{ }129\text{...
We study the photon shot noise dephasing of a superconducting transmon qubit in strong-dispersive limit, due to coupling its readout cavity. As each random arrival or departure is expected completely dephase qubit, we can control rate at which experiences events by varying \textit{in situ} cavity mode population and decay rate. This allows us verify pure mechanism that matches theoretical predictions, fact explains increased seen recent experiments as function cryostat temperature....
Optomechanics is a prime example of light matter interaction, where photons directly couple to phonons, allowing the precise control and measurement state mechanical object. This makes it very appealing platform for testing fundamental physics or sensing applications. Usually, such oscillators are in highly excited thermal states require cooling ground quantum applications, which often accomplished by using optomechanical backaction. However, while massive desirable many tasks, their...
We give a detailed description of the implementation Mølmer–Sørensen gate entangling two 40Ca+ ions using bichromatic laser beam near-resonant with quadrupole transition. By amplitude pulse shaping and compensation ac-Stark shifts we achieve fast operation without compromising error rate. Subjecting different input states to concatenations up 21 individual operations reveals Bell state fidelities above 0.80. In principle, does not require ground cooling as long Lamb–Dicke criterion is...
A basic assumption behind the inequalities used for testing noncontextual hidden variable models is that observables measured on same individual system are perfectly compatible. However, compatibility not perfect in actual experiments using sequential measurements. We discuss resulting "compatibility loophole" and present several methods to rule out certain which obey a kind of extended noncontextuality. Finally, we detailed analysis experimental imperfections recent trapped ion experiment...
We introduce a new gate that transfers an arbitrary state of qubit into superposition two quasi-orthogonal coherent states cavity mode, with opposite phases. This qcMAP is based on conditional and operations exploiting the energy level dispersive shifts, in regime where they are much stronger than linewidths. The generation multi-component superpositions states, non-local entangled resonators multi-qubit GHZ can be efficiently achieved by this gate.
Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying active feedback conditioned on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state combination drives designed entropy evacuation. We propose implement protocol that stabilizes Fock microwave cavity. This is realized with circuit electrodynamics platform where Josephson junction provides direct, nonlinear coupling between two...
Abstract Coherent controlization, i.e., coherent conditioning of arbitrary single- or multi-qubit operations on the state one more control qubits, is an important ingredient for flexible implementation many algorithms in quantum computation. This particular significance when certain subroutines are changing over time they frequently modified, such as decision-making learning agents. We propose a scheme to realize controlization any number superconducting qubits coupled microwave resonator....
Abstract We propose and analyze a passive architecture for realizing on-chip, scalable cascaded quantum devices. In contrast to standard approaches, our scheme does not rely on breaking Lorentz reciprocity. Rather, we engineer the interplay between pairs of superconducting transmon qubits microwave transmission line, in such way that two delocalized orthogonal excitations emit (and absorb) photons propagating opposite directions. show how devices can be exploited passively probe measure...
For quantum-information processing (QIP) with trapped ions, the isotope ${^{43}\text{C}\text{a}}^{+}$ offers combined advantages of a quantum memory long coherence time, high-fidelity readout, and possibility performing two-qubit gates on quadrupole transition narrow-band laser. Compared to other ions used for computing, has relatively complicated level structure. We discuss how meet basic requirements QIP demonstrate ground-state cooling, robust state initialization, efficient readout...
We propose a platform for quantum many body simulations of dipolar spin models using current circuit QED technology. Our basic building blocks are 3D transmon qubits where we use the naturally occurring interactions to realize interacting systems. This opens way toward realization broad class tunable in both two- and one-dimensional geometries. illustrate potential offered by these systems context dimerized Majumdar-Ghosh-type phases, archetypical examples magnetism, showing how such phases...