01926nas a2200181 4500008004100000245010800041210006900149260001300218520132500231100001901556700001901575700002001594700001901614700002901633700002001662700002501682856003701707 2023 eng d00aHigh-Energy Collision of Quarks and Hadrons in the Schwinger Model: From Tensor Networks to Circuit QED0 aHighEnergy Collision of Quarks and Hadrons in the Schwinger Mode c7/5/20233 a
With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in 1+1 dimensions. Working in the bosonized formulation of the model, we propose an analog circuit-QED implementation that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. Furthermore, working in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multi-particle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. This study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.
1 aBelyansky, Ron1 aWhitsitt, Seth1 aMueller, Niklas1 aFahimniya, Ali1 aBennewitz, Elizabeth, R.1 aDavoudi, Zohreh1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2307.0252201900nas a2200157 4500008004100000245008000041210006900121260001400190520140900204100001601613700001801629700001801647700001901665700002101684856003701705 2021 eng d00aDecoding conformal field theories: from supervised to unsupervised learning0 aDecoding conformal field theories from supervised to unsupervise c7/10/20213 aWe use machine learning to classify rational two-dimensional conformal field theories. We first use the energy spectra of these minimal models to train a supervised learning algorithm. We find that the machine is able to correctly predict the nature and the value of critical points of several strongly correlated spin models using only their energy spectra. This is in contrast to previous works that use machine learning to classify different phases of matter, but do not reveal the nature of the critical point between phases. Given that the ground-state entanglement Hamiltonian of certain topological phases of matter is also described by conformal field theories, we use supervised learning on Réyni entropies and find that the machine is able to identify which conformal field theory describes the entanglement Hamiltonian with only the lowest few Réyni entropies to a high degree of accuracy. Finally, using autoencoders, an unsupervised learning algorithm, we find a hidden variable that has a direct correlation with the central charge and discuss prospects for using machine learning to investigate other conformal field theories, including higher-dimensional ones. Our results highlight that machine learning can be used to find and characterize critical points and also hint at the intriguing possibility to use machine learning to learn about more complex conformal field theories.
1 aKuo, En-Jui1 aSeif, Alireza1 aLundgren, Rex1 aWhitsitt, Seth1 aHafezi, Mohammad uhttps://arxiv.org/abs/2106.1348501706nas a2200193 4500008004100000245008500041210006900126260001400195490000600209520111700215100001901332700001901351700001801370700001601388700002401404700002201428700002501450856003701475 2021 eng d00aFrustration-induced anomalous transport and strong photon decay in waveguide QED0 aFrustrationinduced anomalous transport and strong photon decay i c9/16/20210 v33 aWe study the propagation of photons in a one-dimensional environment consisting of two non-interacting species of photons frustratingly coupled to a single spin-1/2. The ultrastrong frustrated coupling leads to an extreme mixing of the light and matter degrees of freedom, resulting in the disintegration of the spin and a breakdown of the "dressed-spin", or polaron, description. Using a combination of numerical and analytical methods, we show that the elastic response becomes increasingly weak at the effective spin frequency, showing instead an increasingly strong and broadband response at higher energies. We also show that the photons can decay into multiple photons of smaller energies. The total probability of these inelastic processes can be as large as the total elastic scattering rate, or half of the total scattering rate, which is as large as it can be. The frustrated spin induces strong anisotropic photon-photon interactions that are dominated by inter-species interactions. Our results are relevant to state-of-the-art circuit and cavity quantum electrodynamics experiments.
1 aBelyansky, Ron1 aWhitsitt, Seth1 aLundgren, Rex1 aWang, Yidan1 aVrajitoarea, Andrei1 aHouck, Andrew, A.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2007.0369002435nas a2200193 4500008004100000245011400041210006900155260001400224300001100238490000800249520181700257100002102074700002402095700001902119700002102138700001902159700002602178856003702204 2021 eng d00aTorus Spectroscopy of the Gross-Neveu-Yukawa Quantum Field Theory: Free Dirac versus Chiral Ising Fixed Point0 aTorus Spectroscopy of the GrossNeveuYukawa Quantum Field Theory c3/15/2021 a1251280 v1033 aWe establish the universal torus low-energy spectra at the free Dirac fixed point and at the strongly coupled chiral Ising fixed point and their subtle crossover behaviour in the Gross-Neuveu-Yukawa field theory with nD=4 component Dirac spinors in D=(2+1) dimensions. These fixed points and the field theories are directly relevant for the long-wavelength physics of certain interacting Dirac systems, such as repulsive spinless fermions on the honeycomb lattice or π-flux square lattice. The torus energy spectrum has been shown previously to serve as a characteristic fingerprint of relativistic fixed points and is a powerful tool to discriminate quantum critical behaviour in numerical simulations. Here, we use a combination of exact diagonalization and quantum Monte Carlo simulations of strongly interacting fermionic lattice models, to compute the critical torus energy spectrum on finite-size clusters with periodic boundaries and extrapolate them to the thermodynamic limit. Additionally, we compute the torus energy spectrum analytically using the perturbative expansion in ε=4−D, which is in good agreement with the numerical results, thereby validating the presence of the chiral Ising fixed point in the lattice models at hand. We show that the strong interaction between the spinor field and the scalar order-parameter field strongly influences the critical torus energy spectrum and we observe prominent multiplicity features related to an emergent symmetry predicted from the quantum field theory. Building on these results we are able to address the subtle crossover physics of the low-energy spectrum flowing from the chiral Ising fixed point to the Dirac fixed point, and analyze earlier flawed attempts to extract Fermi velocity renormalizations from the low-energy spectrum.
1 aSchuler, Michael1 aHesselmann, Stephan1 aWhitsitt, Seth1 aLang, Thomas, C.1 aWessel, Stefan1 aLäuchli, Andreas, M. uhttps://arxiv.org/abs/1907.0537301634nas a2200157 4500008004100000245007000041210006900111260001400180520114300194100001601337700001901353700002401372700001801396700002501414856003701439 2020 eng d00aRealizing and Probing Baryonic Excitations in Rydberg Atom Arrays0 aRealizing and Probing Baryonic Excitations in Rydberg Atom Array c7/14/20203 aWe propose a realization of mesonic and baryonic quasiparticle excitations in Rydberg atom arrays with programmable interactions. Recent experiments have shown that such systems possess a Z3-ordered crystalline phase whose low-energy quasiparticles are defects in the crystalline order. By engineering a Z3-translational-symmetry breaking field on top of the Rydberg-blockaded Hamiltonian, we show that different types of defects experience confinement, and as a consequence form mesonic or baryonic quasiparticle excitations. We illustrate the formation of these quasiparticles by studying a quantum chiral clock model related to the Rydberg Hamiltonian. We then propose an experimental protocol involving out-of-equilibrium dynamics to directly probe the spectrum of the confined excitations. We show that the confined quasiparticle spectrum can limit quantum information spreading in this system. This proposal is readily applicable to current Rydberg experiments, and the method can be easily generalized to more complex confined excitations (e.g. `tetraquarks', `pentaquarks') in phases with Zq order for q>3.
1 aLiu, Fangli1 aWhitsitt, Seth1 aBienias, Przemyslaw1 aLundgren, Rex1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2007.0725802064nas a2200181 4500008004100000245007100041210006900112260001300181520150800194100001901702700001901721700001801740700001601758700002401774700002201798700002501820856003701845 2020 eng d00aTransport and dynamics in the frustrated two-bath spin-boson model0 aTransport and dynamics in the frustrated twobath spinboson model c7/7/20203 aWe study the strong coupling dynamics as well as transport properties of photons in the two-bath spin-boson model, in which a spin-1/2 particle is frustratingly coupled to two independent Ohmic bosonic baths. Using a combination of numerical and analytical methods, we show that the frustration in this model gives rise to rich physics in a very wide range of energies. This is in contrast to the one-bath spin-boson model, where the non-trivial physics occurs at an energy scale close to the renormalized spin frequency. The renormalized spin frequency in the two-bath spin-boson model is still important, featuring in different observables, including the non-equiblirum dynamics of both the spin and the baths along with the elastic transport properties of a photon. The latter however reveals a much more complex structure. The elastic scattering displays non-monotonic behavior at high frequencies, and is very different in the two channels: intra- and inter-bath scattering. The photon can also be inelastically scattered, a process in which it is split into several photons of smaller energies. We show that such inelastic processes are highly anisotropic, with the outgoing particles being preferentially emitted into only one of the baths. Moreover, the inelastic scattering rate is parameterically larger than in the one-bath case, and can even exceed the total elastic rate. Our results can be verified with state-of-the-art circuit and cavity quantum electrodynamics experiments.
1 aBelyansky, Ron1 aWhitsitt, Seth1 aLundgren, Rex1 aWang, Yidan1 aVrajitoarea, Andrei1 aHouck, Andrew, A.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2007.0369001837nas a2200157 4500008004100000245006500041210006400106260001500170520136000185100002001545700001601565700001901581700002501600700001701625856003701642 2019 eng d00aReal-time dynamics of string breaking in quantum spin chains0 aRealtime dynamics of string breaking in quantum spin chains c2019/11/263 aString breaking is a central dynamical process in theories featuring confinement, where a string connecting two charges decays at the expense of the creation of new particle-antiparticle pairs. Here, we show that this process can also be observed in quantum Ising chains where domain walls get confined either by a symmetry-breaking field or by long-range interactions. We find that string breaking occurs, in general, as a two-stage process: First, the initial charges remain essentially static and stable. The connecting string, however, can become a dynamical object. We develop an effective description of this motion, which we find is strongly constrained. In the second stage, which can be severely delayed due to these dynamical constraints, the string finally breaks. We observe that the associated time scale can depend crucially on the initial separation between domain walls and can grow by orders of magnitude by changing the distance by just a few lattice sites. We discuss how our results generalize to one-dimensional confining gauge theories and how they can be made accessible in quantum simulator experiments such as Rydberg atoms or trapped ions.
1 aVerdel, Roberto1 aLiu, Fangli1 aWhitsitt, Seth1 aGorshkov, Alexey, V.1 aHeyl, Markus uhttps://arxiv.org/abs/1911.1138201937nas a2200157 4500008004100000245008200041210006900123260001500192300001200207490000700219520145800226100001901684700002001703700001901723856003701742 2018 eng d00aQuantum field theory for the chiral clock transition in one spatial dimension0 aQuantum field theory for the chiral clock transition in one spat c2018/11/09 a205118 0 vB 3 aWe describe the quantum phase transition in the N-state chiral clock model in spatial dimension d=1. With couplings chosen to preserve time-reversal and spatial inversion symmetries, such a model is in the universality class of recent experimental studies of the ordering of pumped Rydberg states in a one-dimensional chain of trapped ultracold alkali atoms. For such couplings and N=3, the clock model is expected to have a direct phase transition from a gapped phase with a broken global ZN symmetry, to a gapped phase with the ZN symmetry restored. The transition has dynamical critical exponent z≠1, and so cannot be described by a relativistic quantum field theory. We use a lattice duality transformation to map the transition onto that of a Bose gas in d=1, involving the onset of a single boson condensate in the background of a higher-dimensional N-boson condensate. We present a renormalization group analysis of the strongly coupled field theory for the Bose gas transition in an expansion in 2−d, with 4−N chosen to be of order 2−d. At two-loop order, we find a regime of parameters with a renormalization group fixed point which can describe a direct phase transition. We also present numerical density-matrix renormalization group studies of lattice chiral clock and Bose gas models for N=3, finding good evidence for a direct phase transition, and obtain estimates for z and the correlation length exponent ν.
1 aWhitsitt, Seth1 aSamajdar, Rhine1 aSachdev, Subir uhttps://arxiv.org/abs/1808.07056