| 07 X | (Jagiellonian University) Emergence of distinguishability in quantum statistics of strongly correlated fermions Location: MS Teams [ZOA-test], 12:15Department Seminar Online: [link] |
Principal Investigator: Jakub Zakrzewski
Funding institution: Quant-ERA21
Realization: 2022-2025
As of today, Quantum Simulators (QS) are the systems that can address, deepen our understanding of, and ultimately solve some of the most challenging problems of contemporary science: from quantum many body dynamics, through static and transient high Tc superconductivity, to the design of new materials. In DYNAMITE, we will design, realize in the labs, and characterize a new generation of QS with ultracold atoms and beyond. With ascending degree of experimental complexity this involves: (WP1) systems with statistical gauge fields, i.e. “single-component” lattice or continuum systems with density-dependent gauge fields changing the effective quantum statistics of the particles and realizing topological gauge theories; (WP2) systems in dynamical lattices, with “matter” living on the sites, and additional dynamical fields/particles living on the bonds; (WP3) lattice gauge theory models (LGT), from systems with Abelian (Z2, U(1)) to non-Abelian local gauge symmetry. Such systems address questions from condensed matter physics, nuclear physics, high energy physics, and material science: In particular, WP1 allows one to engineer topological gauge theories in the continuum, and to design and control novel types of topological and chiral order, with possible applications to quantum computing and quantum memories. The theoretical and experimental goal here is to tailor the proper matter dependence for the gauge fields, which corresponds to correctly imposing the local symmetry constraint of the gauge theory. WP2 allows one to design and study the interplay between topological order and symmetry breaking. Simpler systems without gauge invariance that are already simulated in the labs, permit us indeed to study the fundamental question of how gauge theory phenomena translate into systems of coupled degrees of freedom without explicit gauge symmetry and how gauge symmetry can emerge. WP3 allows us to study statics of the confinement-deconfinement transition, and more importantly its dynamics, relation to absence/presence of thermalization, the dynamical role of many body localization and quantum scars. While experimental work will focus on Abelian LGTs, theory will design as well scalable implementations of nonAbelian symmetries. In DYNAMITE, experiment and theory will be inseparably entangled. Its results will provide unprecedented control over salient phenomena at the frontier of quantum many-body physics.
Principal Investigator: Jakub Zakrzewski
Funding institution: NCN, OPUS-LAP
Realization: 2022-2025
Interaction of particles leads to exchange of energy among them and typically, for open systems to their thermalization. The same phenomenon occurs for closed systems, where a local small part typically thermalizes due to contact with the rest .Last fifteen years brought intensive studies of cases, when this picture does not work. It was shown, almost proved, that in strongly disordered systems we observe many-body localization, the nonergodic behaviour that leads to a strong memory of the initial state and weak exchange of the information between the time-evolved state and the rest of the system. In last five years it became more and more apparent that nonergodic dynamics may occur also in the absence of the disorder, even more surprisingly violating ETH. Several systems were shown to exhibit such a behavior. It was shown, for example, that the global tilt of one-dimensional system, analogous to the potential of a charged particle in electric field, leads to such a nonergodic dynamics. This has been associated with the so called shattering of the Hilbert space and the existence of emerging almost conserved constants of motions (such as a global dipole moment). Similarly low dimensional lattice gauge theory models show nonergodic motion that may be traced back to the existence of a generalized Gauss law. It has been suggested that strong, long range interactions or the so called frustration lead also to the nonergodic behaviour. This project aims at understanding of the occurrence of the non-ergodic dynamics in strongly interacting many-body systems. What are the necessary ingredients for the system to behave in a nonergodic way? Are approximate constant of motions necessary? What is the relation to the structure of the Hilbert space? What is the behaviour of the observables, in particular of the associated, the so called, spectral functions that reflect the frequency response of the observables? The aim is to understand the limits of generality, the necessary ingredients, identifying characteristic features of models leading to such a nonergodic behavior. The project is planned in a close collaboration between Slovenian and Polish teams. Both of them study various aspects of interacting many-body systems for a number of years, working recently both on MBL as well as on disorderless systems such as fermions (spins) in tilted lattices, examples of constrained dynamics in lattice gauge theories, systems with global conservation laws etc.
Principal Investigator: Krzysztof Sacha
Funding institution: NCN, Maestro 13
Realization: 2022-2027
Time crystals are quantum many-body systems that due to interactions between particles are able to spontaneously self-organize and start performing periodic motion. Spontaneous formation of periodic behavior in time is a temporal analogue of self-organization of atoms in space and formation of ordinary space crystals. Research on quantum time crystals was initiated by a Nobel Laureate Frank Wilczek in 2012. Since then, research on time crystals has developed a lot. Periodically driven systems have become perfect platforms for investigation of time crystals. Spontaneous formation of periodic motion in such systems was proposed and experimentally realized. Various condensed matter phenomena have been predicted in periodically driven systems. For example, Anderson localization, many-body localization, insulating phases and topological phases have been theoretically demonstrated in the time domain.
Electronics, spintronics and atomtronics are fields where condensed matter phenomena are explored to research and realize useful devices. The described state-of-the-art indicates that we can already start developing condensed matter devices where time crystalline structures are the key element. This will pave the way for the new field of {\it time-tronics} which can be investigated in many different experimentally attainable systems. Our goal is to propose time-tronic devices and to find optimal experimental platforms for their realization and to convince scientists that time-tronics is attainable in present-day laboratories.
Principal Investigator: Jakub Zakrzewski
Funding institution: NCN, Opus 18
Realization: 2020-2024
This project is a direct continuation of the Opus 10 project under the same title - for results click here: http://chaos.if.uj.edu.pl/~kuba/Opus10/). The scientific aim of present project is the analysis of many-body localization in nontrivial models based on cold atomic systems placed in optical lattice potential. Such a potential results from a non-resonant interaction of laser light with atoms. Using counter-propagating laser beams one creates a standing wave resulting in a periodic potential in which atoms move. This resembles the situation of electrons in crystals, except that atoms are electrically neutral. Electron transport in metals is very effective - metals are good conductors. Still in the pioneering work in the late fifties Anderson postulated that randomly placed defects, modelled by addition of the disorder to the system, may profoundly influence the transport properties (he has shown it for noninteracting particles - the phenomenon now called Anderson localization). For interacting particles the situation is more dicult and we do not know the full answer yet as a full numerical analysis is prohibitive. Only in the last 15 years a significant progress has been made resulting in several theoretical papers as well as numerical simulations showing that in the presence of strong interactions and strong disorder the so called many-body localization (MBL) may appear. Why this is interesting? The behaviour od interacting particles in an isolated system is of fundamental importance. We expect that due to interactions all local information will spread over the whole system. MBL limits the transfer of information, so it may be locally contained and then stored to our profitt. MBL may lead to the fact that a small subsystem remembers, at least partially, its initial conditions despite interaction with the remaining parts of the system. thus no thermalization occurs. The information is not only encoded in the global observables of the full system but also it is stored in local averages or correlations for a subsystem. There is just a single step more (may be not a small step) to quantum storage of information in a similar way as it is presently classically stored on hard discs. Models going beyond a single dimension, possibly with nontrivial topological properties will be studied.
Principal Investigator: Mateusz Łącki
Funding institution: NCN, Opus 18
Realization: 2020-2024
The project is about studying systems where the spatial resolution for potential created for ultracold atoms using only lasers is signigicatnly beyond the diffractive limit.
Laser standing wave are now routinely used to create lattice potentials that simulate condensed matter problems. One of the limitation is inability to create lattices with features smaller than half of the lase wavelength. Recently we have proposed a method to create potential that allow to increase the resolution by an order of magnitude. It is based on populating a system of strongly coupled atomic levels by a gas that macroscopically populates the levels invonved, in coherent way. The original proposal [PRL, 117, 233001 (2016)] and its experimental verification [PRL, 120,083601 (2018)] for fermionic isotope of Ytterbium.
The scientific aim of this project is to study broadening the scope of applicability of the construction to bosonic species, go beyond confines of one dimensional system.
Principal Investigator: Krzysztof Sacha
Funding institution: Australian Research Council, Grant ID: DP190100815
Realization: 2019-2023
This project aims to create a new exotic form of quantum matter in which a many-body system of ultracold atoms bouncing on a vibrating mirror spontaneously self-organises its motion with a period tens of times longer than the driving period of the mirror. Such ‘time crystals’ are predicted to be robust against external perturbations and to persist for very long times. The project expects to generate new knowledge on exotic non-equilibrium crystalline phenomena in the time domain, such as many-body localisation with temporal disorder, which has counter-intuitive characteristics such as absence of thermalisation and vanishing direct current transport. Time crystals could provide significant benefits for the storage and transfer of quantum information, and this, and other outcomes may ultimately lead to commercialproducts.
Principal Investigator: Jakub Zakrzewski
Funding institution: NCN Unisono (Quantera)
Realization: 2018-2021
The project will develop classical simulation methods based on tensor networks, and develop and run quantum software on experimental quantum simulation platforms. From the technological point of view, this research will allow the study and design of novel materials with topological error correcting capabilities, which will play a central role in the quest for building a scalable quantum computer.
Principal Investigator: Karol Życzkowski
Funding institution: Team-Net , Foundation for Polish Science (FNP)
Realization: 2019-2023
Near Term quantum computers: Challenges, optimal implementations and applications. The project aims at characterizing the computational power and investigating possible practical applications of quantum computing devices consisting of a limited number of imperfect qubits. To realize the goals we have formed a network of closely collaborating research groups working on cutting-edge aspects of quantum computing. The consortium has been established by three Polish institutions working in the field of quantum information science: Center for Theoretical Physics of the Polish Academy of Sciences, Faculty of Physics, Astronomy and Applied Computer Science of Jagiellonian University and Institute of Theoretical and Applied Informatics of the Polish Academy of Sciences. It runs four research groups:
Principal Investigator: Krzysztof Sacha
Funding institution: NCN, Opus 16
Realization: 2019-2022
In the group of Prof. Peter Hannaford in Swinburne University of Technology in Melbourne there will be performed experiments on time crystals in ultra-cold atoms bouncing on an oscillating atom mirror. We will constitute the theoretical force of the experiments. The Project is also devoted to theoretical research of crystalline structures in time.
Principal Investigator: Krzysztof Sacha
Funding institution: NCN Unisono (Quantera)
Realization: 2018-2021
In the past decades, quantum technologies have been fast developing from proof-of-principle experiments to ready-to-the-market solutions; with applications in many different fields ranging from quantum sensing, metrology, and communication to quantum simulations. Recently, the study of gauge theories has been recognized as an unexpected field of application of quantum technologies. Gauge theories describe some of the most fundamental and intriguing processes occurring in Nature, ranging from the interaction of elementary high energy particles – described by the Standard Model – to condensed matter systems displaying frustration or topological order. Despite being at the heart of our understanding of many fundamental processes, these systems elude most of our investigative approaches in the non-perturbative regime, whenever real-time dynamics, finite fermionic densities and other problems with complex action are involved and the infamous sign problem hinders the effectiveness of Monte Carlo methods. Thus, developing novel approaches without such limitations will pave the way to unprecedented research possibilities and exciting developments. This is the project’s goal: to develop a new quantum-based sign-problem-free technology to simulate strongly correlated many-body quantum systems with Abelian and non-Abelian dynamical gauge degrees of freedom and to apply them to the study of lower dimensional gauge theories, ultimately and in the very long run aiming at Quantum Chromodynamics. This interdisciplinary project can be developed only within a collaborative effort of different groups as it will exploit knowledge from experimental and theoretical branches of quantum optics; atomic, molecular and optical physics; quantum information science; high energy physics and condensed matter. The results of this project will serve as benchmarks for the first generation of quantum simulators and will have far reaching consequences in different fundamental and applied fields of science ranging from materials science and quantum chemistry to astrophysics. From the technological point of view, this research will allow the study and design of novel materials with topological error correcting codes.
Principal Investigator: Jakub Zakrzewski
Funding institution: NCN, Symfonia 4
Realization: 2016-2021
In 1999 Ahmet Zeweil won the Nobel Prize in Chemistry for his work on femtochemistry, that is on developing techniques to use laser pulses to “photograph” chemical reactions on the scale of femtoseconds. The dream of the XXI century is the observation of complex quantum dynamics on sub-femtosecond and sub-nanometer scales in physical, chemical and biological systems. Atto-science is a key technology to realize this with table top/low cost physics. In atto-science ultrashort laser pulses are impinged on matted to produce yet shorter atto-second (thousand times shorter than femto) pulses of ultraviolet (UV) or even X-ray radiation, and electrons of surprisingly high kinetic energy. The attosecond XUV pulses can be used to test dynamics of atoms, molecules, solids, 2D solids like graphene, biomolecules, biocomplexes etc. The present proposal focuses on developing theory and experiments to understand the essence of the relevant physics, especially in the contexts of many body effects, neglected so far in standard descriptions. Our main and in fact THE goal is the realization of the dream: observation of complex quantum dynamics on sub-femtosecond and sub-nanometer scales. This will allow to understand numerous processes of primary importance for chemistry, bio-photonics and biology.
Principal Investigator: Karol Życzkowski
Funding institution: NCN, Maestro 7
Realization: 2016-2021
Proposed project aims to establish closer links between uncertainty relations and quantum entanglement. Entropic uncertainty relations, generalized for the cases of several arbitrary quantum measurements, will provide new methods to detect quantum entanglement and to characterize this effect. A complementary aim of the project consists in deriving generalized uncertainty relations for the cases of composed systems, in which effects of quantum entanglement play an important role.
Principal Investigator: Jakub Zakrzewski
Funding institution: NCN, Opus 11
Realization: 2017-2020
The aim of this project is to construct and test propositions for many body models with unusual and interesting properties - the exotic quantum matter - obtained using periodic modulations of the parameters of a given setup (lattice depth, strength of the interactions). Sounds complicated? It is not. Ultra cold atoms form an intriguing state of matter in which atoms must be treated as waves. Waves that may be steered using laser radiation which imposed effective forces on atoms. In the standing wave laser field atoms feel the periodic potential like electrons in a solid. We want to control the atoms even better to be able to create new exciting systems with unusual properties. The additional knob to tune we can use is a periodic in time change of system’s parameters. The period of parameters’ change (be it laser frequency or phase to shake the lattice position, laser intensity to vary its depth, magnetic field to vary interactions) may be adjusted creating resonance effects. Like the swing which has its characteristic swing frequency (depending on its length, moment of inertia). If the frequency of our force will not be adapted to the parameters of the swing - the effect will be negligible. for the frequency close to the swing characteristic frequency the oscillations of the swing will become large. it will swing with the external frequency given by us. Resonant driving is efficient.
