A5064695066- Mechanical and Optical Resonators
- Quantum Information and Cryptography
- Photonic and Optical Devices
- Quantum Computing Algorithms and Architecture
- Advanced MEMS and NEMS Technologies
- Quantum and electron transport phenomena
- Force Microscopy Techniques and Applications
- Quantum many-body systems
- Particle physics theoretical and experimental studies
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Chromodynamics and Particle Interactions
- Quantum optics and atomic interactions
- Advanced Fiber Laser Technologies
- Quantum Mechanics and Applications
- Nuclear physics research studies
- Geophysics and Sensor Technology
- Neural Networks and Reservoir Computing
- Quantum Mechanics and Non-Hermitian Physics
- Spectroscopy and Quantum Chemical Studies
- High-Energy Particle Collisions Research
- Topological Materials and Phenomena
- Laser-Matter Interactions and Applications
- Tensor decomposition and applications
- Photonic Crystals and Applications
- Magneto-Optical Properties and Applications
University of Copenhagen
2024-2025
Max Planck Institute of Quantum Optics
2019-2024
Technical University of Munich
2022-2024
Munich Center for Quantum Science and Technology
2020-2023
Max Planck Society
2021
University of Cambridge
2016-2019
University College London
2017
Friedrich-Alexander-Universität Erlangen-Nürnberg
1988-1993
University of Illinois System
1991
European Organization for Nuclear Research
1991
Directional amplifiers are an important resource in quantum information processing, as they protect sensitive systems from excess noise. Here, we propose implementation of phase-preserving and phase-sensitive directional for microwave signals electromechanical setup comprising two cavities mechanical resonators. We show that both can reach their respective limits on added In the reverse direction, emit thermal noise stemming resonators discuss how this be suppressed, a crucial aspect...
We consider the preparation of matrix product states (MPS) on quantum devices via circuits local gates. first prove that faithfully preparing translation-invariant normal MPS $N$ sites requires a circuit depth $T=\mathrm{\ensuremath{\Omega}}(\mathrm{log}N)$. then introduce an algorithm based renormalization-group transformation to prepare with error $\ensuremath{\epsilon}$ in $T=O[\mathrm{log}(N/\ensuremath{\epsilon})]$, which is optimal. also show measurement and feedback leads exponential...
Abstract Nonreciprocal microwave devices are ubiquitous in radar and radio communication indispensable the readout chains of superconducting quantum circuits. Since they commonly rely on ferrite materials requiring large magnetic fields that make them bulky lossy, there has been significant interest magnetic-field-free on-chip alternatives, such as those recently implemented using Josephson nonlinearity. Here, we realize reconfigurable nonreciprocal transmission between two modes purely...
We introduce plaquette projected entangled-pair states, a class of states in lattice that can be generated by applying sequential unitaries acting on plaquettes overlapping regions. They satisfy area-law entanglement, possess long-range correlations, and naturally generalize other relevant classes tensor network states. identify subclass more efficiently prepared radial fashion contains the family isometric [M. P. Zaletel F. Pollmann, Phys. Rev. Lett. 124, 037201...
The Affleck-Kennedy-Lieb-Tasaki (AKLT) states have significant applications in condensed matter physics and quantum computation. An adiabatic path that enables the deterministic preparation of a broad range many-body states, including AKLT on arbitrary lattice geometries, is proposed. numerical results 1D 2D demonstrate high efficiency this approach.
We determine the computational power of isometric tensor-network states (isoTNSs), a variational ansatz originally developed to numerically find and compute properties gapped ground topological in two dimensions. By mapping two-dimensional isoTNSs (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:mn>1</a:mn><a:mo>+</a:mo><a:mn>1</a:mn></a:math>)D unitary quantum circuits, we that computation local expectation values (including those with...
Topology is quickly becoming a cornerstone in our understanding of electronic systems. Like their counterparts, bosonic systems can exhibit topological band structure, but real materials it difficult to ascertain nature, as ground state simple condensate or the vacuum, and one has rely instead on excited states, for example characteristic thermal Hall response. Here we propose driving magnon insulator with an electromagnetic field show that this causes edge mode instabilities large...
Directional transport is obtained in various multimode systems by driving multiple, nonreciprocally interfering interactions between individual bosonic modes. However, sustaining the required number of modes become physically complex. In our microwave-optomechanical experiment, we show how to configure nonreciprocal frequency components a single superconducting cavity coupled two drumhead oscillators. The are promoted Floquet and generate missing dimension realize an isolator directional...
Quantum mechanics imposes a limit on the precision of continuous position measurement harmonic oscillator, due to backaction arising from quantum fluctuations in field. This standard can be surpassed by monitoring only one two non-commuting quadratures motion, known as backaction-evading measurement. technique has not been implemented using optical interferometers date. Here we demonstrate, cavity optomechanical system operating domain, two-tone localized gigahertz-frequency mechanical mode...
Previous theoretical and experimental research has shown that current NISQ devices constitute powerful platforms for analogue quantum simulation. With the exquisite level of control offered by state-of-the-art computers, we show one can go further implement a wide class Floquet Hamiltonians, or timedependent Hamiltonians in general. We then single-qubit version these models IBM Quantum Experience experimentally realize temporal Bernevig-Hughes-Zhang Chern insulator. From our data infer...
Both non-Hermitian systems and the behaviour of emitters coupled to structured baths have been studied intensely in recent years. Here we study interplay these paradigmatic settings. In a series examples, show that single quantum emitter bath displays number unconventional behaviours, many without Hermitian counterpart. We first consider unidirectional hopping lattice whose complex dispersion forms loop. identify peculiar bound states inside loop as manifestation skin effect. same setting,...
Backaction-evading measurements of mechanical motion can achieve precision below the zero-point uncertainty and quantum squeezing, which makes them a resource for metrology information processing. We provide an exact expression conditional state optomechanical system in two-tone backaction-evading measurement beyond standard adiabatic approximation perform extensive numerical simulations to go usual rotating-wave approximation. predict simultaneous presence intracavity entanglement. further...
A cornerstone assumption that most literature on discrete time crystals has relied is homogeneous Floquet systems generally heat to a featureless infinite temperature state, an expectation motivated researchers in the field mostly focus many-body localized systems. Some works have however shown standard diagnostics for crystallinity apply equally well clean settings without disorder. This fact raises question whether crystal possible which originally expected heating evaded. Studying both...
We establish a general framework for studying the bound states and photon-emission dynamics of quantum emitters coupled to structured nanophotonic lattices with engineered dissipation (loss). In single-excitation sector, system can be described exactly by non-Hermitian formalism. have pointed out in accompanying letter [Gong et al., Phys. Rev. Lett. 129, 223601 (2022)] that single emitter one-dimensional lattice may already exhibit anomalous behaviors without Hermitian counterparts. Here we...
We develop a Floquet approach to solve time-periodic quantum Langevin equations in steady state. show that two-time correlation functions of system operators can be expanded Fourier series and generalized Wiener-Khinchin theorem relates the transform their zeroth component measured spectrum. apply our framework bichromatically driven cavity optomechanical systems, setting which mechanical oscillators have recently been prepared quantum-squeezed states. Our method provides an intuitive way...
The fundamental question of how information spreads in closed quantum many-body systems is often addressed through the lens bipartite entanglement entropy, a quantity that describes correlations comprehensive (nonlocal) way. Among most striking features entropy are its unbounded linear growth thermodynamic limit, asymptotic extensivity finite-size systems, and possibility measurement-induced phase transitions, all which have no obvious classical counterpart. Here, we show these key...
Most experiments with ultracold atoms in optical lattices have contact interactions and therefore operate at high densities of around one atom per site to observe the effect strong interactions. Strong ranged can be generated via Rydberg dressing, which opens up path exploring physics few interacting particles. Rather than unit cells a crystal, sites lattice now interpreted as discretized space. This allows study completely new types problems familiar architecture. We investigate possibility...
We experimentally assess the suitability of transmon qubits with fixed frequencies and interactions for realization analogue quantum simulations spin systems. test a set necessary criteria this goal on commercial processor using full process tomography more efficient Hamiltonian tomography. Significant single qubit errors at low amplitudes are identified as limiting factor preventing currently available devices. additionally find spurious dynamics in absence drive pulses, which we identify...
Understanding thermalization in quantum many-body systems is among the most enduring problems modern physics. A particularly interesting question concerns role played by mechanics this process, i.e., whether fundamentally different from that classical and, if so, which of its features are genuinely quantum. Here, we study minimally structured only constrained to have local interactions, random circuits. In particular, introduce permutation circuits (RPCs), comprising gates locally permute...
We study the superradiant decay of a chain atoms coupled to chiral waveguide, focusing on regime non-negligible photon propagation time. Using an exact master equation description that accounts for delay effects, we obtain evidence suggest competition between collective and retardation leads emergence effective maximum number able contribute dynamics, resulting in plateau peak emission rate. To develop this analysis further, investigate interatomic correlations find features consistent with...
We analyze the entanglement structure of states generated by random constant-depth two-dimensional quantum circuits, followed projective measurements a subset sites. By deriving rigorous lower bound on average entropy such postmeasurement states, we prove that macroscopic long-ranged is above some constant critical depth in several natural classes circuit architectures, which include brickwork circuits and holographic tensor networks. This behavior had been conjectured based previous works,...
We consider an optomechanical cavity that is driven stroboscopically by a train of short pulses. By suitably choosing the inter-pulse spacing we show ground-state cooling and mechanical squeezing can be achieved, even in presence dissipation for moderate radiation-pressure interaction. provide full quantum-mechanical treatment stroboscopic backaction-evading measurements, which give simple analytic insight, discuss preparation verification squeezed states. further driving pair...
Abstract Sources of entangled electromagnetic radiation are a cornerstone in quantum information processing and offer unique opportunities for the study many-body physics controlled experimental setting. Generation multi-mode states with large entanglement length, that is neither probabilistic nor restricted to generate specific types states, remains challenging. Here, we demonstrate fully deterministic generation purely photonic such as cluster, GHZ, W state by sequentially emitting...