A5038844670- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum and electron transport phenomena
- Mechanical and Optical Resonators
- Quantum optics and atomic interactions
- Diamond and Carbon-based Materials Research
- Advanced Fiber Laser Technologies
- Quantum Mechanics and Applications
- Strong Light-Matter Interactions
- Topological Materials and Phenomena
- CCD and CMOS Imaging Sensors
- Biofield Effects and Biophysics
- Quantum many-body systems
- Neural Networks and Reservoir Computing
- Advancements in Photolithography Techniques
- Quantum Electrodynamics and Casimir Effect
- Medical Imaging Techniques and Applications
- Computational Physics and Python Applications
- Spectroscopy and Quantum Chemical Studies
- Quantum-Dot Cellular Automata
- Extraction and Separation Processes
- Cold Atom Physics and Bose-Einstein Condensates
- Parallel Computing and Optimization Techniques
- Force Microscopy Techniques and Applications
- Recycling and Waste Management Techniques
IQM (Germany)
2023
IQM (Finland)
2022
University of Konstanz
2012-2016
Tunable coupling of superconducting qubits has been widely studied due to its importance for isolated gate operations in scalable quantum processor architectures. Here, we demonstrate a tunable qubit-qubit coupler based on floating transmon device, which allows us place at least 2 mm apart from each other while maintaining over 50-MHz between the and qubits. In introduced tunable-coupler design, both qubit-coupler couplings are mediated by two waveguides instead relying direct capacitive...
We study theoretically the entanglement of two-photon states in ground state intersubband cavity system, i.e., so-called polariton vacuum. The system consists a sequence doped quantum wells located inside microcavity and photons can interact with excitations wells. Using an explicit solution for operated ultrastrong-coupling regime, postselection is introduced, where only certain are considered analyzed mode entanglement. find that fast quench coupling creates entangled degree depends on...
Abstract Digital-analog quantum computation (DAQC) has recently been proposed as an alternative to the standard paradigm of digital (DQC). DAQC generates entanglement through a continuous or analog evolution whole device, rather than by applying two-qubit gates. This manuscript describes in-depth analysis errors in implementing Ising Hamiltonians used for arbitrary computations, which was missing from previous literature, revealing that, overall, scale less favorably compared those DQC. As...
Quantum computers with a limited qubit connectivity require inserting SWAP gates for routing, which increases gate execution errors and the impact of environmental noise due to an overhead in circuit depth. In this work, we benchmark various routing techniques considering random quantum circuits on one-dimensional square lattice connectivities, employing both analytical numerical methods. We introduce fidelity as comprehensive metric that captures effects depth overheads. Leveraging novel...
Defect centers in diamond are exceptional solid-state quantum systems that can have exceedingly long electron and nuclear spin coherence times. So far, single-qubit gates for the nitrogen spin, a two-qubit gate with nitrogen-vacancy (NV) center entanglement between nearby spins been demonstrated. Here, we develop scheme to implement universal two distant spins. Virtual excitation of an NV is embedded optical cavity scatter laser photon into mode; show this process depends on state atom. If...
Abstract Enhancing the performance of noisy quantum processors requires improving our understanding error mechanisms and ways to overcome them. A judicious selection qubit design parameters plays a pivotal role in processors. In this study, we identify optimal ranges for parameters, grounded comprehensive noise modeling. To end, also analyze effect charge-parity switch caused by quasiparticles on two-qubit gate. Due utilization second excited state transmon, where charge dispersion is...
Large-scale quantum computation requires a fast assessment of the main sources error in implemented gates. To this aim, we provide learning based framework that allows to extract contribution each physical noise source infidelity series gates with small number experimental measurements. illustrate method, consider case superconducting transmon architectures, where focus on diabatic implementation CZ gate tunable couplers. In context, account for all relevant sources, including non-Markovian...
A crucial task to obtain optimal and reliable quantum devices is quantify their overall performance. The average fidelity of gates a particular figure merit that can be estimated efficiently by Randomized Benchmarking (RB). However, the concept gate-fidelity itself relies on assumption noise behaves in predictable, time-local, or so-called Markovian manner, whose breakdown naturally become leading source errors as scale size depth. We analytically show error suppression techniques such...
Digital-Analog Quantum Computation (DAQC) has recently been proposed as an alternative to the standard paradigm of digital quantum computation. DAQC creates entanglement through a continuous or analog evolution whole device, rather than by applying two-qubit gates. This manuscript describes in-depth analysis extending its implementation arbitrary connectivities and performing first systematic study scaling properties. We specify for three examples algorithms, showing that except few specific...
While the power of quantum computers is commonly acknowledged to rise exponentially, it often overlooked that complexity noise mechanisms generally grows much faster. In particular, quantifying whether instructions on a processor are close being unitary has important consequences concerning error rates, e.g., for confidence in their estimation, ability mitigate them efficiently, or relation fault-tolerance thresholds correction. However, estimating coherence, unitarity, scales exponentially...
Accurate noise characterization is essential for reliable quantum computation. Effective Pauli models have emerged as powerful tools, offering detailed description of the error processes with a manageable number parameters, which guarantees scalability procedure. However, fundamental limitation in learnability fidelities impedes full high-accuracy both general and effective noise, thereby restricting e.g., performance noise-aware mitigation techniques. We introduce Multi-Layer Cycle...
Entanglement purification allows the creation of qubit pairs arbitrarily high fidelity with respect to a maximally entangled state, starting from larger number low-fidelity pairs. Purification requires quantum memory, role for which electron spins are well suited. However, using existing recurrence protocols involving symmetric local two-qubit operations spin qubits turns out be rather unpractical. We present an efficient protocol requiring only single pulsed Heisenberg- or XY-type exchange...
Tunable coupling of superconducting qubits has been widely studied due to its importance for isolated gate operations in scalable quantum processor architectures. Here, we demonstrate a tunable qubit-qubit coupler based on floating transmon device which allows us place at least 2 mm apart from each other while maintaining over 50 MHz between the and qubits. In introduced tunable-coupler design, both qubit-coupler couplings are mediated by two waveguides instead relying direct capacitive...
Enhancing the performance of noisy quantum processors requires improving our understanding error mechanisms and ways to overcome them. In this study, we identify optimal ranges for qubit design parameters, grounded in comprehensive noise modeling. To end, also analyze a previously unexplored mechanism that can perturb two-qubit gates due charge-parity switches caused by quasiparticles. Due utilization higher levels transmon, where charge dispersion is significantly larger, switch will affect...