Most Recent Preprints
Observation of magnon bound states in the long-range, anisotropic Heisenberg model
arXiv:2212.03899
Toggle Abstract
Over the recent years coherent, time-periodic modulation has been established as a versatile tool for realizing novel Hamiltonians. Using this approach, known as Floquet engineering, we experimentally realize a long-ranged, anisotropic Heisenberg model with tunable interactions in a trapped ion quantum simulator. We demonstrate that the spectrum of the model contains not only single magnon excitations but also composite magnon bound states. For the long-range interactions with the experimentally realized power-law exponent, the group velocity of magnons is unbounded. Nonetheless, for sufficiently strong interactions we observe bound states of these unconventional magnons which possess a non-diverging group velocity. By measuring the configurational mutual information between two disjoint intervals, we demonstrate the implications of the bound state formation on the entanglement dynamics of the system. Our observations provide key insights into the peculiar role of composite excitations in the non-equilibrium dynamics of quantum many-body systems.
Levitated Optomechanics with Meta-Atoms
arXiv:2211.08235
Autonomous quantum error correction and fault-tolerant quantum computation with squeezed cat qubits
arXiv:2210.13406
Toggle Abstract
We propose an autonomous quantum error correction scheme using squeezed cat (SC) code against the dominant error source, excitation loss, in continuous-variable systems. Through reservoir engineering, we show that a structured dissipation can stabilize a two-component SC while autonomously correcting the errors. The implementation of such dissipation only requires low-order nonlinear couplings among three bosonic modes or between a bosonic mode and a qutrit. While our proposed scheme is device independent, it is readily implementable with current experimental platforms such as superconducting circuits and trapped-ion systems. Compared to the stabilized cat, the stabilized SC has a much lower dominant error rate and a significantly enhanced noise bias. Furthermore, the bias-preserving operations for the SC have much lower error rates. In combination, the stabilized SC leads to substantially better logical performance when concatenating with an outer discrete-variable code. The surface-SC scheme achieves more than one order of magnitude increase in the threshold ratio between the loss rate κ1 and the engineered dissipation rate κ2. Under a practical noise ratio κ1/κ2=10−3, the repetition-SC scheme can reach a 10−15 logical error rate even with a small mean excitation number of 4, which already suffices for practically useful quantum algorithms.
Enhancing Detection of Topological Order by Local Error Correctio
arXiv:2209.12428
Toggle Abstract
More Preprints
The exploration of topologically-ordered states of matter is a long-standing goal at the interface of several subfields of the physical sciences. Such states feature intriguing physical properties such as long-range entanglement, emergent gauge fields and non-local correlations, and can aid in realization of scalable fault-tolerant quantum computation. However, these same features also make creation, detection, and characterization of topologically-ordered states particularly challenging. Motivated by recent experimental demonstrations, we introduce a new approach for quantifying topological states -- locally error-corrected decoration (LED) -- by combining methods of error correction with ideas of renormalization-group flow. Our approach allows for efficient and robust identification of topological order, and is applicable in the presence of incoherent noise sources, making it particularly suitable for realistic experiments. We demonstrate the power of LED using numerical simulations of the toric code under a variety of perturbations, and we subsequently apply it to an experimental realization of a quantum spin liquid using a Rydberg-atom quantum simulator. Extensions to the characterization of other exotic states of matter are discussed.
All Publications
Research Groups
-
The research group led by Rainer Blatt investigates quantum processes in a system of few ions held in ion traps. The experiments aim at achieving complete control over all quantum degrees of freedom in...
Quantum Optics and Spectroscopy -
The research team led by Francesca Ferlaino focuses on the study of dipolar quantum phenomena, using strongly magnetic atomic species. In 2012, the group has created the first Bose-Einstein...
Dipolar Quantum Gases -
The research group led by R. GRIMM investigates ultracold particle systems consisting of optically trapped quantum gases at temperatures close to absolute zero. Because of their superb experimental...
Ultracold Atoms and Quantum Gases -
Gerhard Kirchmair’s research group works on superconducting circuits and their application for quantum computation and simulation. Superconducting Josephson junctions are used to realize the quantum...
Superconducting quantum circuits -
The research group led by Hannes Pichler studies quantum optical systems, quantum many-body physics and quantum information. The group aims at laying the theoretical foundations for next generation...
Many-Body Quantum Optics -
The research group led by Oriol Romero-Isart studies topics in the fields of theoretical quantum optics and quantum nanophysics in the context of quantum science and technology. One of the main...
Quantum Nanophysics, Optics and Information -
Wittgenstein awardee Peter Zoller’s research group studies topics in the fields of theoretical quantum optics and atomic physics as well as quantum information and condensed matter theory. The...
Quantum Optics