BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Uwe-Jens Wiese (University of Bern) DTSTART:20200528T133000Z DTEND:20200528T143000Z DTSTAMP:20260424T222701Z UID:tTmuQFTseminar/1 DESCRIPTION:Title: Asymptotically free quantum fields from dimensional reductio n of discrete variables\nby Uwe-Jens Wiese (University of Bern) as par t of t-\,T- & mu dependence in QFT\n\n\nAbstract\nQuantum Chromodynamics ( QCD) is the (3+1)-d asymptotically free relativistic SU(3) gauge theory th at is formulated in terms of fundamental quark and gluon fields. CP(N-1) m odels in (1+1)-d have a global SU(N) symmetry and share many features with QCD. They are also asymptotically free\, have a non-perturbatively genera ted mass gap\, and non-trivial theta vacuum states. CP(N-1) models can be regularized unconventionally by using discrete SU(N) quantum spins forming a (2+1)-d spin ladder that consists of n transversely coupled quantum spi n chains. The (1+1)-d asymptotically free CP(N-1) fields then emerge from dimensional reduction when n is increased. Even n leads to the vacuum angl e theta=0\, while odd n leads to theta=pi. In a similar way\, gluon fields emerge naturally from the dimensional reduction of (4+1)-d quantum links\ , which are discrete gauge variables that generalize quantum spins. In thi s formulation\, quarks arise as domain wall fermions. In contrast to the u sual quantum fields\, quantum spins and quantum links realize asymptotical ly free field theories with finite-dimensional local Hilbert spaces. This is advantageous in the context of quantum simulation experiments. Both CP( N-1) models and QCD can be quantum simulated with ultra-cold alkaline-eart h atoms in optical super-lattices. When CP(N-1) models are studied at non- zero chemical potential\, non-trivial condensed matter physics arises in t hese quantum field theories. In particular\, there are Bose-Einstein conde nsates\, with and without ferromagnetism.\n LOCATION:https://stable.researchseminars.org/talk/tTmuQFTseminar/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Yi Yin (Quark Matter Research Center\, Institute of Modern Physics (Chinese Academy of Science)) DTSTART:20200611T133000Z DTEND:20200611T143000Z DTSTAMP:20260424T222701Z UID:tTmuQFTseminar/2 DESCRIPTION:Title: Quark-gluon plasma\, the QCD critical point and Hydro+\n by Yi Yin (Quark Matter Research Center\, Institute of Modern Physics (Chi nese Academy of Science)) as part of t-\,T- & mu dependence in QFT\n\n\nAb stract\nHeavy-ion collisions at RHIC and LHC produce quark-gluon plasma (Q GP) whose bulk evolution is well described by relativistic hydrodynamics. However\, to further explore the properties of QGP and the phase diagram o f QCD\, one typically has to go beyond this hydrodynamic paradigm. In this talk\, I will present the development of a general dynamic framework whic h couples slow non-hydro. modes with hydro. modes\, namely Hydro+. I will demonstrate the application of Hydro+ to describe off-equilibrium dynamics near the conjectured QCD critical point. If time permits\, I will briefly report my recent attempt to explore the dynamic properties of QGP in the non-hydrodynamic yet non-perturbative regime.\n LOCATION:https://stable.researchseminars.org/talk/tTmuQFTseminar/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Uwe-Jens Wiese (University of Bern) DTSTART:20200702T133000Z DTEND:20200702T143000Z DTSTAMP:20260424T222701Z UID:tTmuQFTseminar/3 DESCRIPTION:Title: Asymptotically free quantum fields from dimensional reductio n of discrete variables (Part 2)\nby Uwe-Jens Wiese (University of Ber n) as part of t-\,T- & mu dependence in QFT\n\n\nAbstract\nQuantum Chromod ynamics (QCD) is the (3+1)-d asymptotically free relativistic SU(3) gauge theory that is formulated in terms of fundamental quark and gluon fields. CP(N-1) models in (1+1)-d have a global SU(N) symmetry and share many feat ures with QCD. They are also asymptotically free\, have a non-perturbative ly generated mass gap\, and non-trivial theta vacuum states. CP(N-1) model s can be regularized unconventionally by using discrete SU(N) quantum spin s forming a (2+1)-d spin ladder that consists of n transversely coupled qu antum spin chains. The (1+1)-d asymptotically free CP(N-1) fields then eme rge from dimensional reduction when n is increased. Even n leads to the va cuum angle theta=0\, while odd n leads to theta=pi. In a similar way\, glu on fields emerge naturally from the dimensional reduction of (4+1)-d quant um links\, which are discrete gauge variables that generalize quantum spin s. In this formulation\, quarks arise as domain wall fermions. In contrast to the usual quantum fields\, quantum spins and quantum links realize asy mptotically free field theories with finite-dimensional local Hilbert spac es. This is advantageous in the context of quantum simulation experiments. Both CP(N-1) models and QCD can be quantum simulated with ultra-cold alka line-earth atoms in optical super-lattices. When CP(N-1) models are studie d at non-zero chemical potential\, non-trivial condensed matter physics ar ises in these quantum field theories. In particular\, there are Bose-Einst ein condensates\, with and without ferromagnetism.\n LOCATION:https://stable.researchseminars.org/talk/tTmuQFTseminar/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Markus Heyl (MPI Dresden) DTSTART:20200709T133000Z DTEND:20200709T143000Z DTSTAMP:20260424T222701Z UID:tTmuQFTseminar/4 DESCRIPTION:Title: Quantum many-body dynamics in two dimensions with artificial neural networks\nby Markus Heyl (MPI Dresden) as part of t-\,T- & mu dependence in QFT\n\n\nAbstract\nThe efficient numerical simulation of non equilibrium real-time evolution in isolated quantum matter constitutes a k ey challenge for current computational methods. This holds in particular i n the regime of two spatial dimensions\, whose experimental exploration is currently pursued with strong efforts in quantum simulators. In this work we present a versatile and efficient machine learning inspired approach b ased on a recently introduced artificial neural network encoding of quantu m many-body wave functions. We identify and resolve some key challenges fo r the simulation of time evolution\, which previously imposed significant limitations on the accurate description of large systems and long-time dyn amics. As a concrete example\, we study the dynamics of the paradigmatic t wo-dimensional transverse field Ising model\, as recently also realized ex perimentally in systems of Rydberg atoms. Calculating the nonequilibrium r eal-time evolution across a broad range of parameters\, we\, for instance\ , observe collapse and revival oscillations of ferromagnetic order and dem onstrate that the reached time scales are comparable to or exceed the capa bilities of state-of-the-art tensor network methods. [arXiv:1912.08828]\n LOCATION:https://stable.researchseminars.org/talk/tTmuQFTseminar/4/ END:VEVENT END:VCALENDAR