A5046587562- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Quantum Computing Algorithms and Architecture
- Quantum optics and atomic interactions
- Advanced Thermodynamics and Statistical Mechanics
- Cold Atom Physics and Bose-Einstein Condensates
- Mechanical and Optical Resonators
- Quantum Mechanics and Applications
- Scientific Computing and Data Management
- Gyrotron and Vacuum Electronics Research
- Laser-Matter Interactions and Applications
- Parallel Computing and Optimization Techniques
- Particle accelerators and beam dynamics
- Neural Networks and Reservoir Computing
- Semiconductor Quantum Structures and Devices
- Microwave Engineering and Waveguides
- Superconducting and THz Device Technology
- Strong Light-Matter Interactions
- Photonic and Optical Devices
- Magnetic confinement fusion research
- Advanced Frequency and Time Standards
- Advanced Memory and Neural Computing
- Robotic Process Automation Applications
- Radio Frequency Integrated Circuit Design
Bavarian Academy of Sciences and Humanities
2013-2021
Technical University of Munich
2015-2021
Aalto University
2018-2021
IQM (Finland)
2020-2021
University of Oulu
2019
VTT Technical Research Centre of Finland
2019
Siemens (Germany)
1984
We report on ultrastrong coupling between a superconducting flux qubit and resonant mode of system comprised two coplanar stripline resonators coupled galvanically to the qubit. With strength as high 17% frequency, exceeding that previous circuit quantum electrodynamics experiments, we observe pronounced Bloch-Siegert shift. The spectroscopic response our multimode reveals clear breakdown Jaynes-Cummings model. In contrast earlier is achieved without making use an additional inductance...
Displacement of propagating quantum states light is a fundamental operation for communication. It enables studies on macroscopic coherence and plays an important role in teleportation protocols with continuous variables. In our experiments, we have successfully implemented this squeezed microwave states. We demonstrate that, even strong displacement amplitudes, there no degradation the squeezing level reconstructed Furthermore, confirm that path entanglement generated by using displaced...
We realize a device allowing for tunable and switchable coupling between two superconducting resonators mediated by an artificial atom. For the latter, we utilize persistent current flux qubit. characterize in frequency time domain find that relevant modes can be varied controlled way. Specifically, tuned adjusting through qubit loop or saturating Our measurements allow us to parameter regimes optimal switch performance with respect drive power dynamic range of resonator input power.
We realize tunable coupling between two superconducting transmission line resonators. The is mediated by a non-hysteretic rf SQUID acting as flux-tunable mutual inductance the present spectroscopic characterization of device. In particular, we observe couplings $g/2\pi$ ranging −320 MHz and 37 MHz. case $g \simeq 0$ , microwave power cross resonators reduced almost four orders magnitude compared to where switched on.
Superconducting quantum circuits are potential candidates to realize a large-scale computer. The envisioned large density of integrated components, however, requires proper thermal management and control dissipation. To this end, it is advantageous utilize tunable dissipation channels exploit the optimized heat flow at exceptional points (EPs). Here, we experimentally an EP in superconducting microwave circuit consisting two resonators. singularity point Hamiltonian, corresponds most...
We present a systematic analysis of the internal losses superconducting coplanar waveguide microwave resonators based on niobium thin films silicon substrates. In particular, we investigate introduced by Nb/Al interfaces in center conductor, which is important for experiments where Al Josephson junctions are integrated into Nb circuits. find that these can be strong source two-level state (TLS) losses, when not positioned at current nodes resonator. addition to TLS including Al,...
In experiments with superconducting quantum circuits, characterizing the photon statistics of propagating microwave fields is a fundamental task. We quantify n^{2}+n number variance thermal photons emitted from blackbody radiator for mean numbers, 0.05≲n≲1.5. probe using either correlation measurements or transmon qubit coupled to resonator. Our provide precise quantitative characterization weak states and information on noise by Josephson parametric amplifier.
For gradiometric three-Josephson-junction flux qubits, we perform a systematic study on the tuning of minimal transition frequency, so-called qubit gap. By replacing one qubit's Josephson junctions by dc superconducting quantum interference device (SQUID), critical current this SQUID and, in turn, gap can be tuned situ control threading loop. We present spectroscopic measurements demonstrating well-defined controllability between zero and more than 10 GHz. This is important for into out...
Josephson parametric amplifiers (JPA) have become key devices in quantum science and technology with superconducting circuits. In particular, they can be utilized as quantum-limited or a source of squeezed microwave fields. Here, we report on the detailed measurements five flux-driven JPAs, three them exhibiting hysteretic dependence resonant frequency versus applied magnetic flux. We model measured characteristics by numerical simulations based two-dimensional potential landscape dc...
We theoretically propose and experimentally implement a method of measuring qubit by driving it close to the frequency dispersively coupled bosonic mode. The separation states corresponding different begins essentially immediately at maximum rate, leading speedup in measurement protocol. Also mode can be simultaneously driven optimize speed fidelity. test this protocol using superconducting resonator For certain time, we observe that conventional dispersive readout yields 100% higher average...
We report on fast tunability of an electromagnetic environment coupled to a superconducting coplanar waveguide resonator. Namely, we utilize recently developed quantum-circuit refrigerator (QCR) experimentally demonstrate dynamic in the total damping rate resonator up almost two orders magnitude. Based theory, it corresponds change internal by nearly four The control QCR is fully electrical, with shortest implemented operation times range 10 ns. This experiment constitutes active reset...
Abstract Two-mode squeezing is a fascinating example of quantum entanglement manifested in cross-correlations non-commuting observables between two subsystems. At the same time, these subsystems themselves may contain no signatures their self-correlations. These properties make two-mode squeezed (TMS) states an ideal resource for applications communication. Here, we generate propagating microwave TMS by beam splitter distributing single mode emitted from distinct Josephson parametric...
The emerging quantum technological applications call for fast and accurate initialization of the corresponding devices to low-entropy states. To this end, we theoretically study a recently demonstrated quantum-circuit refrigerator in case nonlinear electric circuits such as superconducting qubits. maximum refrigeration rate transmon flux qubits is observed be roughly an order magnitude higher than that usual linear resonators, increasing flexibility design. We find typical experimental...
The Lamb shift, an energy shift arising from the presence of electromagnetic vacuum, has been observed in various quantum systems and established as part independent environmental photon number. However, typical studies are based on simplistic bosonic models which may be challenged practical devices. We demonstrate a hybrid bosonic-fermionic environment for linear resonator mode observe that number can dramatically increase both dissipation effective mode. Our observations quantitatively...
A superconducting qubit coupled to an open transmission line represents implementation of the spin-boson model with a broadband environment. We show that this environment can be engineered by introducing partial reflectors into line, allowing shape spectral function, J({\omega}), model. The function accessed measuring resonance fluorescence qubit, which provides information on both and coupling between line. without is found Ohmic over wide frequency range, whereas peaked density for shaped...
The concept of parity describes the inversion symmetry a system and is fundamental relevance in standard model, quantum information processing, field theory. In electrodynamics, conserved large gradients are required to engineer light-matter interaction operator. this work, we potassiumlike artificial atom represented by specifically designed superconducting flux qubit. We control wave function with an effective orbital momentum provided resonator. By irradiating spatially shaped microwave...
Superconducting 3D microwave cavities offer state-of-the-art coherence times and a well-controlled environment for superconducting qubits. In order to realize at the same time fast readout long-lived quantum information storage, one can couple qubit both low-quality high-quality storage cavity. However, such systems are bulky compared their less coherent 2D counterparts. A more compact scalable approach is achieved by making use of multimode structure our work, we investigate device where...
Thermal microwave states are omnipresent noise sources in superconducting quantum circuits covering all relevant frequency regimes. We use them as a probe to identify three second-order decoherence mechanisms of transmon qubit. First, we quantify the efficiency resonator filter dispersive Jaynes–Cummings regime and find evidence for parasitic loss channels. Second, low-frequency demonstrate expected T3 temperature dependence qubit dephasing rate. Finally, show that parameter fluctuations due...
Various applications of quantum devices call for an accurate calibration cryogenic amplification chains. To this end, we present a convenient scheme and use it to accurately measure the total gain noise temperature chain by employing normal-metal--insulator--superconductor (NIS) junctions. Our method is based on radiation emitted inelastic electron tunneling across voltage-biased NIS We derive analytical equation that relates generated power applied bias voltage which only control parameter...
We have fabricated and studied a system of two tunable coupled nonlinear superconducting resonators. The nonlinearity is introduced by galvanically dc quantum interference devices. simulate the response means circuit model, which includes an additional signal path electromagnetic environment. Furthermore, we present methods allowing us to experimentally determine nonlinearity. First, fit measured frequency flux dependence transmission data simulations based on equivalent model. Second, power...
Abstract Quantum computing holds the potential to deliver great economic prosperity European Union (EU). However, creation of successful business in field is challenging owing required extensive investments into postdoctoral-level workforce and sophisticated infrastructure without an existing market that can financially support these operations. This commentary paper reviews recent efforts taken EU foster quantum-computing ecosystem together with its current status. Importantly, we propose...