A5068956359- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Quantum Computing Algorithms and Architecture
- Physics of Superconductivity and Magnetism
- Quantum optics and atomic interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Mechanics and Applications
- Mechanical and Optical Resonators
- Gyrotron and Vacuum Electronics Research
- Physical Unclonable Functions (PUFs) and Hardware Security
- Advanced Memory and Neural Computing
- Advanced Thermodynamics and Statistical Mechanics
- Neural Networks and Reservoir Computing
- Strong Light-Matter Interactions
- Acoustic Wave Resonator Technologies
- Superconducting and THz Device Technology
- Photonic and Optical Devices
- MXene and MAX Phase Materials
- Advanced Frequency and Time Standards
- Microwave and Dielectric Measurement Techniques
- Graphene research and applications
- Force Microscopy Techniques and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Electrical Measurement Techniques
- Perovskite Materials and Applications
LMU Klinikum
2023
Ludwig-Maximilians-Universität München
2023
Bavarian Academy of Sciences and Humanities
2012-2021
Technical University of Munich
2012-2021
Nanosystems Initiative Munich
2015-2018
Joint Research Center
2002
Path entanglement constitutes an essential resource in quantum information and communication protocols. Here, we demonstrate frequency-degenerate between continuous-variable microwaves propagating along two spatially separated paths. We combine a squeezed vacuum state using microwave beam splitter. Via correlation measurements, detect quantify the path contained splitter output state. Our experiments open avenue to teleportation, communication, or radar with continuous variables at frequencies.
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...
Josephson parametric amplifiers (JPA) are promising devices for applications in circuit quantum electrodynamics and studies on propagating microwaves because of their good noise performance. In this work, we present a systematic characterization flux-driven JPA at millikelvin temperatures. particular, study detail its squeezing properties by two different detection techniques. With the homodyne setup, observe vacuum fluctuations superposing signal idler bands. For quantitative analysis,...
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.
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.
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...
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...
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...
Abstract Controllable and reproducible synthesis of 2D materials is crucial for their future applications. Chemical vapor deposition (CVD) promises scalable high‐quality growth materials. However, to optimize CVD growth, multiple parameters have be carefully selected. Design experiments (DoE) a consistent versatile tool all simultaneously in controlled way. This study exploits DoE statistical approaches show how the transition metal dichalcogenides (TMDs) can optimized, using tungsten...
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...
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...
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...
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...
Quantum microwave photonics aims at generating, routing, and manipulating propagating quantum fields in the spirit of optical photonics. To this end, strong nonlinearities superconducting circuits can be used to either improve or move beyond implementation concepts from domain. In context, design a well-controlled broadband environment for is central task. work, we place transmon qubit one arm an on-chip Mach-Zehnder interferometer composed two beam splitters. By measuring its relaxation...
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 From mode distance observed in spectroscopy experiments, we derive strength ranging -320MHz and 37 MHz. In case where about zero, microwave power cross resonators can be reduced almost four orders of magnitude compared to switched on. addition, observe parametric amplification applying suitable additional drive tone.
Closed quantum systems follow a unitary time evolution that can be simulated on computers. By incorporating non-unitary effects via, e.g., measurements ancilla qubits, these algorithms extended to open-system dynamics, such as Markovian processes described by the Lindblad master equation. In this paper, we analyze convergence criteria and speed of Markovian, purely dissipative random walk an unstructured search space. We analytically derive mixing for continuous- discrete-time different...