Browsing by Author "Zhang, Chuanwei"
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Item Adiabatically Tuning Quantized Supercurrents in an Annular Bose-Einstein Condensate(2018-08-20) Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, Chuanwei; Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, ChuanweiThe ability to generate and tune quantized persistent supercurrents is crucial for building superconducting or atomtronic devices with novel functionalities. In ultracold atoms, previous methods for generating quantized supercurrents are generally based on dynamical processes to prepare atoms in metastable excited states. Here, we show that arbitrary quantized circulation states can be adiabatically prepared and tuned as the ground state of a ring-shaped Bose-Einstein condensate by utilizing spin-orbital-angular-momentum (SOAM) coupling and an external potential. There exists superfluid hysteresis for tuning supercurrents between different quantization values with nonlinear atomic interactions, which is explained by developing a nonlinear Landau-Zener theory. Our work will provide a powerful platform for studying SOAM-coupled ultracold atomic gases and building atomtronic circuits.Item Analysis of Heme Functions in Therapy Resistance and Tumorigenesis in Non-small Cell Lung Cancer(2021-08-01T05:00:00.000Z) Dey, Sanchareeka; Zhang, Li; Zhang, Chuanwei; Reitzer, Lawrence J.; Burr, John G.; Misra, JyotiLung cancer remains the leading cause of cancer-related death in the United States, 84% of them being non-small cell lung cancer (NSCLC). Early-stage treatment includes surgery and radiotherapy followed by periodic radiographic imaging for routine surveillance. These curative treatments have shown promise in some lung cancer patients while being ineffective for majority (30–60%) of the patients who are predicted to have advanced disease, particularly local or distant metastasis. This limit overall survival rates in these patients to less than 60%. Moreover, despite the advent of personalized therapy which includes various targeted therapies and immunotherapies, there has not been a significant improvement in the 5-year survival rate. Therefore, there is a pressing need to further optimize current strategies while continuing to explore novel strategies to improve therapeutic outcomes for patients with lung cancer, based on individual patient needs. Numerous studies are now focusing on the importance of mitochondrial respiration or oxidative phosphorylation (OXPHOS) in cancer progression. However, very little is known about its role and potential as a therapeutic target in non-small cell lung cancer (NSCLC). Several studies in our lab show that NSCLC cells display elevated levels of intracellular heme. This increased level of heme is either through de novo heme synthesis or heme uptake. Our lab has also demonstrated elevated mitochondrial respiration/oxidative phosphorylation (OXPHOS) in NSCLCs. Studies in our lab show that elevated expression of enzymes involved in heme biosynthesis, uptake, and degradation, as well as oxygen-utilizing hemoproteins in resistant cells post treatment with vascular disrupting agents. Limiting oxidative functions using Cyclopamine tartrate (CycT), inhibition of heme uptake with heme sequestering peptides (HSP2) and heme synthesis using succinyl acetone, have all shown promise in delaying growth and progression of NSCLC cells and tumor xenografts. Another feature of NSCLC tumor is its heterogeneity. NSCLCs exhibit widespread inter- and intra-tumoral heterogeneity as well as incidences of subtype transdifferentiation. This kind of plasticity enable them to develop drug resistance and pose great challenges for their treatment. In this study I aimed to understand the comparative dependence of the two major NSCLC subtypes, adenocarcinoma (ADC) and squamous cell carcinoma (SCC), on heme and OXPHOS, for their growth and progression. I observed that both ADC and SCC have similar demands for heme uptake and synthesis in cell culture. My results also suggest that OXPHOS activities are elevated in both ADC and SCC to support tumorigenic functions in culture. I used the Genetically Engineered Mouse Model (GEMM), KLLuc to study NSCLC tumor heterogeneity since tumors developed in these mice consists of both ADC and SCC phenotypes. My findings in vitro were corroborated in this model, using immunohistochemistry (IHC) and histology. Bioluminescence imaging and histology studies demonstrate that heme sequestering peptides successfully reduce tumor development and progression in KLLuc mice.Item Anisotropic Weyl Fermions from the Quasiparticle Excitation Spectrum of a 3D Fulde-Ferrell Superfluid(American Physical Society, 2014-04-04) Xu, Yong; Chu, Rui-Lin; Zhang, Chuanwei; Zhang, ChuanweiWeyl fermions, first proposed for describing massless chiral Dirac fermions in particle physics, have not been observed yet in experiments. Recently, much effort has been devoted to explore Weyl fermions around band touching points of single-particle energy dispersions in certain solid state materials (named Weyl semimetals), similar as graphene for Dirac fermions. Here we show that such Weyl semimetals also exist in the quasiparticle excitation spectrum of a three-dimensional spin-orbit-coupled Fulde-Ferrell superfluid. By varying Zeeman fields, the properties of Weyl fermions, such as their creation and annihilation, number and position, as well as anisotropic linear dispersions around band touching points, can be tuned. We study the manifestation of anisotropic Weyl fermions in sound speeds of Fulde-Ferrell fermionic superfluids, which are detectable in experiments.Item Berezinskii-Kosterlitz-Thouless Phase Transition in 2D Spin-Orbit-Coupled Fulde-Herrell Superfluids(American Physical Society, 2015-03-17) Xu, Yong; Zhang, Chuanwei; Zhang, ChuanweiThe experimental observation of traditional Zeeman-field induced Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids has been hindered by various challenges, in particular, the requirement of low dimensional systems. In 2D, finite temperature phase fluctuations lead to an extremely small Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for FFLO superfluids, raising serious concerns regarding their experimental observability. Recently, it was shown that FFLO superfluids can be realized using a Rashba spin-orbit coupled Fermi gas subject to Zeeman fields, which may also support topological excitations such as Majorana fermions in 2D. Here we address the finite temperature BKT transition issue in this system, which may exhibit gapped, gapless, topological, and gapless topological FF phases. We find a large BKT transition temperature due to large effective superfluid densities, making it possible to observe 2D FF superfluids at finite temperature. In addition, we show that gapless FF superfluids can be stable due to their positive superfluid densities. These findings pave the way for the experimental observation of 2D gapped and gapless FF superfluids and their associated topological excitations at finite temperature.Item Bright Solitons in a Two-Dimensional Spin-Orbit-Coupled Dipolar Bose-Einstein Condensate(American Physical Society, 2015-07-27) Xu, Y.; Zhang, Y.; Zhang, Chuanwei; Zhang, ChuanweiWe study a two-dimensional spin-orbit-coupled dipolar Bose-Einstein condensate with repulsive contact interactions by both the variational method and the imaginary-time evolution of the Gross-Pitaevskii equation. The dipoles are completely polarized along one direction in the two-dimensional plane to provide an effective attractive dipole-dipole interaction. We find two types of solitons as the ground states arising from such attractive dipole-dipole interactions: a plane-wave soliton with a spatially varying phase and a stripe soliton with a spatially oscillating density for each component. Both types of solitons possess smaller size and higher anisotropy than the soliton without spin-orbit coupling. Finally, we discuss the properties of moving solitons, which are nontrivial because of the violation of Galilean invariance.Item Dark Solitons with Majorana Fermions in Spin-Orbit-Coupled Fermi Gases(American Physical Society, 2014-09-26) Xu, Yong; Mao, Li; Wu, Biao; Zhang, Chuanwei; Zhang, ChuanweiWe show that a single dark soliton can exist in a spin-orbit-coupled Fermi gas with a high spin imbalance, where spin-orbit coupling favors uniform superfluids over nonuniform Fulde-Ferrell-Larkin-Ovchinnikov states, leading to dark soliton excitations in highly imbalanced gases. Above a critical spin imbalance, two topological Majorana fermions without interactions can coexist inside a dark soliton, paving a way for manipulating Majorana fermions through controlling solitons. At the topological transition point, the atom density contrast across the soliton suddenly vanishes, suggesting a signature for identifying topological solitons.Item Dynamical Spin-Density Waves in a Spin-Orbit-Coupled Bose-Einstein Condensate(Amer Physical Soc, 2015-07-31) Li, Yan; Qu, Chunlei; Zhang, Yongsheng; Zhang, Chuanwei; Li, Yan; Qu, Chunlei; Zhang, Yongsheng; Zhang, ChuanweiSynthetic spin-orbit (SO) coupling, an important ingredient for quantum simulation of many exotic condensed matter physics, has recently attracted considerable attention. The static and dynamic properties of a SO-coupled Bose-Einstein condensate (BEC) have been extensively studied in both theory and experiment. Here we numerically investigate the generation and propagation of a dynamical spin-density wave (SDW) in a SO-coupled BEC using a fast moving Gaussian-shaped barrier. We find that the SDW wavelength is sensitive to the barrier's velocity while varies slightly with the barrier's peak potential or width. We qualitatively explain the generation of SDW by considering a rectangular barrier in a one-dimensional system. Our results may motivate future experimental and theoretical investigations of rich dynamics in the SO-coupled BEC induced by a moving barrier.Item Dzyaloshinskii-Moriya Interaction and Spiral Order in Spin-Orbit Coupled Optical Lattices(Nature Publishing Group, 2015-05-27) Gong, Ming; Qian, Yinyin; Yan, Mi; Scarola, V. W.; Zhang, Chuanwei; H-3571-2011 (Zhang, C); Zhang, ChuanweiWe show that the recent experimental realization of spin-orbit coupling in ultracold atomic gases can be used to study different types of spin spiral order and resulting multiferroic effects. Spin-orbit coupling in optical lattices can give rise to the Dzyaloshinskii-Moriya (DM) spin interaction which is essential for spin spiral order. By taking into account spin-orbit coupling and an external Zeeman field, we derive an effective spin model in the Mott insulator regime at half filling and demonstrate that the DM interaction in optical lattices can be made extremely strong with realistic experimental parameters. The rich finite temperature phase diagrams of the effective spin models for fermions and bosons are obtained via classical Monte Carlo simulations.Item Emergent Kinetics and Fractionalized Charge in 1D Spin-Orbit Coupled Flatband Optical Lattices(2014-03-18) Lin, Fei; Zhang, Chuanwei; Scarola, V. W.; Zhang, ChuanweiRecent ultracold atomic gas experiments implementing synthetic spin-orbit coupling allow access to flatbands that emphasize interactions. We model spin-orbit coupled fermions in a one-dimensional flatband optical lattice. We introduce an effective Luttinger-liquid theory to show that interactions generate collective excitations with emergent kinetics and fractionalized charge, analogous to properties found in the two-dimensional fractional quantum Hall regime. Observation of these excitations would provide an important platform for exploring exotic quantum states derived solely from interactions.Item Exciton Polaritons in Transition-Metal Dichalcogenides and Their Direct Excitation via Energy Transfer(2015-08-28) Gartstein, Yuri N.; Li, Xiao; Zhang, Chuanwei; 6603852436 (Gartstein, Yuri)Excitons, composite electron-hole quasiparticles, are known to play an important role in optoelectronic phenomena in many semiconducting materials. Recent experiments and theory indicate that the band-gap optics of the newly discovered monolayer transition-metal dichalcogenides (TMDs) is dominated by tightly bound valley excitons. The strong interaction of excitons with long-range electromagnetic fields in these two-dimensional systems can significantly affect their intrinsic properties. Here, we develop a semiclassical framework for intrinsic exciton polaritons in monolayer TMDs that treats their dispersion and radiative decay on the same footing and can incorporate effects of the dielectric environment. It is demonstrated how both inter- and intravalley long-range interactions influence the dispersion and decay of the polaritonic eigenstates. We also show that exciton polaritons can be efficiently excited via resonance energy transfer from quantum emitters such as quantum dots, which may be useful for various applications.Item Exotic Phases and Quantum Dynamics in Spin-Orbit Coupled Bose-Einstein Condensates(2021-07-21) Hou, Junpeng; Zhang, ChuanweiIn this dissertation, we study a range of exotic quantum phases and dynamics in BoseEinstein condensates (BECs) with spin-orbit (SO) coupling. Firstly, inspired by the recent experimental progresses in engineering supersolid stripe states in a SO-coupled BEC, we conjecture a new quantum state of matter called “superfluid-qausicrystal”, in which quasicrystalline orders form spontaneously in the ground states of the BECs. We propose a realistic setup to prepare and observe this exotic quantum states and confirm its existence through both variational ansatz analysis and direct simulation of mean-field Gross-Pitaevskii equation (GPE). Moreover, we have identified rich phase diagram including superfluid-qausicrystals, supersoilds and plane-wave phases. By utilizing the double-well band structure of a SO-coupled BEC, we propose and investigate a momentum-pace Josephson junction (MSJJ). We show that, under an extra pair of Raman lasers, the two band minimums in momentum space can be weakly coupled. In such a MSJJ, Josephson currents can be induced not only by applying the equivalent of “voltages”, but also by tuning tunneling phases. We characterize the MSJJs through both full mean-field analysis and a concise two-level model and demonstrate the important role of interactions between atoms. Besides, we experimentally demonstrate that this can be a route for realizing a striped BEC, providing an accessible platform to investigate the excitation spectra and other important properties of supersolid-like states. We observe coherent Rabi oscillations in momentum space between two band minima and demonstrate a long lifetime of the ground state, which find good agreements with mean-field simulations. Finally, we theoretically conceive and experimentally demonstrate a non-magnetic one-way spin switch device using a SO-coupled BEC subjected to a moving spin-independent repulsive dipole potential. We show that the physical foundation of this unidirectional device is based on the breakdown of Galilean invariance in the presence of SO coupling. The experimental observation, the numerical simulations and the theoretic interpretations are consistent with the others.Item FFLO Superfluids in 2d Spin-Orbit Coupled Fermi Gases(2014-10-07) Zheng, Zhen; Gong, Ming; Zhang, Yichao; Zou, Xubo; Zhang, Chuanwei; Guo, Guangcan; Zhang, ChuanweiWe show that the combination of spin-orbit coupling and in-plane Zeeman field in a two-dimensional degenerate Fermi gas can lead to a larger parameter region for Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phases than that using spin-imbalanced Fermi gases. The resulting FFLO superfluids are also more stable due to the enhanced energy difference between FFLO and conventional Bardeen-Cooper-Schrieffer (BCS) excited states. We clarify the crucial role of the symmetry of Fermi surface on the formation of finite momentum pairing. The phase diagram for FFLO superfluids is obtained in the BCS-BEC crossover region and possible experimental observations of FFLO phases are discussed.Item Floquet Fulde-Ferrell-Larkin-Ovchinnikov Superfluids and Majorana Fermions in a Shaken Fermionic Optical Lattice(Amer Physical Soc, 2015-06-22) Zheng, Zhen; Qu, Chunlei; Zou, Xubo; Zhang, Chuanwei; Zheng, Zhen; Qu, Chunlei; Zhang, ChuanweiFulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids, Cooper pairings with finite momentum, and Majorana fermions (MFs), quasiparticles with non-Abelian exchange statistics, are two topics under intensive investigation in the past several decades, but unambiguous experimental evidence for them has not been found yet. Here we show that the recent experimentally realized shaken optical lattice provides a pathway to realize FFLO superfluids and MFs. By tuning the shaking frequency and amplitude, various couplings between the s and p orbitals of the lattice (called the pseudospins) can be generated. We show that the combination of the s- and p-band dispersion inversion, the engineered pseudospin coupling, and the on-site attractive interaction naturally allows the observation of FFLO superfluids as well as MFs in different parameter regions.Item Fulde-Ferrell Superfluids without Spin Imbalance in Driven Optical Lattices(Amer Physical Soc) Zheng, Zhen; Qu, Chunlei; Zou, Xubo; Zhang, Chuanwei; Zhang, ChuanweiSpin-imbalanced ultracold Fermi gases have been widely studied recently as a platform for exploring the long-sought Fulde-Ferrell-Larkin-Ovchinnikov superfluid phases, but so far conclusive evidence has not been found. Here we propose to realize an Fulde-Ferrell (FF) superfluid without spin imbalance in a three-dimensional fermionic cold atom optical lattice, where s- and p-orbital bands of the lattice are coupled by another weak moving optical lattice. Such coupling leads to a spin-independent asymmetric Fermi surface, which, together with the s-wave scattering interaction between two spins, yields an FF type of superfluid pairing. Unlike traditional schemes, our proposal does not rely on the spin imbalance (or an equivalent Zeeman field) to induce the Fermi surface mismatch and provides a completely new route for realizing FF superfluids.Item Inversion Asymmetry, Flavortronics, and Nonlinear Optics in Two-dimensional Materials(August 2022) Cheung, Patrick; Zhang, Fan; Stern, Robert; Gartstein, Yuri; King, Lindsay J.; Kolodrubetz, Michael; Zhang, ChuanweiInterests in two-dimensional (2D) materials have grown tremendously after the successful isolation of a single layer graphene. The properties of 2D materials are often very different from their 3D counterparts. They offer great flexibilities in tuning their electronic and optical properties through numerous ways. For example, electronic properties not only greatly vary with the number of layers in the materials, they can also depend strongly on the relative twists among different layers. Besides scientific advances and discoveries, these findings have led to enormous efforts being put in band gap engineering and the more recent moir ́e engineering to ensure that they fulfill their unprecedented potential in technological applications. In this dissertation, we study this emerging and exciting platform. Our era of electronics is made possible through advances in semiconductor technology based on the precise manipulation of electronic charge degree of freedom. However, there are additional degrees of freedom, such as spin, layer and valley, that electrons in materials may possess. Methods to fabricate workable devices based on the manipulation of these degrees of freedom to process and store information have been extensively studied in the literature. Here, we take a step further. We consider another degree of freedom, SU(3) flavor, that exists in the so-called Q-valleys of n-type few-layer transition metal dichalcogenides. In the quantum Hall regime, Landau levels form triplets that are each three-fold degenerate. When each Landau level triplet is one-third filled or empty, we predict that a pure flavor nematic phase and a flavorless charge-density-wave phase will occur respectively below and above a critical magnetic field. Electrons carry flavor-dependent electric dipole moments even at zero magnetic field, giving rise to a nematic ferroelectric state. We further show that the flavor degree of freedom can be manipulated by an electric field, leading to a new concept: flavortronics. The local density of states of electrons in materials will be modified when they are scattered off impurities. This results in quasiparticle interference (QPI) that can be probed by scanning tunneling spectroscopy. We then study QPI of Q-valley electrons scattering off localized non- magnetic and magnetic impurities. More importantly, we propose that QPI provides a way to observe the above predicted nematic ferroelectric state. Finally, we study a moir ́e metamaterial, namely twisted double bilayer graphene (TDBG). The electronic and optical properties in twisted multilayer systems are very different from the single layer counterpart. The highly tunable quantum geometric properties of TDBG give rise to tunable photoresponses that are closely related to the polarization states, power and wavelength of the incident light. This close relationship enables us to generate a set of photovoltage maps that can be used to train a convolutional neural network to decode the properties of an unknown incoming light from its unique photovoltage map. This enables an unprecedented intelligent light sensing in an extremely compact, on-chip manner.Item Majorana Fermions in Quasi-One-Dimensional and Higher-Dimensional Ultracold Optical Lattices(2015-08-14) Qu, Chunlei; Gong, Ming; Xu, Yong; Tewari, Sumanta; Zhang, Chuanwei; Qu, Chunlei; Zhang, ChuanweiWe study Majorana fermions (MFs) in quasi-one dimensional (quasi-1D) and higher-dimensional fermionic optical lattices with a strictly 1D spin-orbit coupling, which has already been realized in cold atom experiments. We show that when the superfluid order parameters are homogeneous and are enforced to be identical along different chains, there are multiple MFs at each end with or without an experimentally tunable in-plane Zeeman field V{y}. For V{y} = 0 the multiple MFs are topologically protected by a chiral symmetry; however, for V{y} ≠ 0 the existence of multiple MFs is related to the peculiar spectrum properties of the system despite the broken chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero-energy flat band. Furthermore, when the superfluid order parameters are solved self-consistently, the multiple MFs are usually destroyed because of the inhomogeneous order parameters of either Bardeen-Cooper-Schrieffer (V{y} = 0) type or Fulde-Ferrell (V{y} ≠ 0). Our results are useful to guide the experimentalists on searching for MFs in ultracold spin-orbit coupled fermionic superfluids.Item Momentum Space Aharonov-Bohm Interferometry in Rashba Spin-Orbit Coupled Bose-Einstein Condensates(Institute of Physics Publishing) Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, Chuanwei; 4042455 (Zhang, C); Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, ChuanweiThe recent experimental realization of synthetic Rashba spin-orbit coupling (SOC) paves a new avenue for exploring topological phases in ultracold atoms. The unequivocal characterization of such topological physics requires a simple scheme for measuring the Berry phase originating from the SOC. Here we propose a scheme to realize momentum space Aharonov-Bohm interferometry in a Rashba spin-orbit-coupled Bose-Einstein condensate through a sudden change of the in-plane Zeeman field. We find that the π Berry phase for the Dirac point of the Rashba SOC is directly revealed by a robust dark interference fringe in the momentum space. An external perpendicular Zeeman field opens a band gap at the Dirac point, which reduces the Berry phase along the Rashba ring, leading to lower brightness of the interference fringe. We develop a variational model with semiclassical equations of motion of essential dynamical quantities for describing the interference process, yielding real and momentum space trajectories and geometric phases agreeing with the real-time simulation of the Gross-Pitaevskii equation. Our study may pave the way for the experimental detection of Berry phases in ultracold atomic systems and further exploration of momentum space interference dynamics.Item Momentum-Space Josephson Effects(Amer Physical Soc) Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Bersano, Thomas; Gokhroo, Vandna; Mossman, Sean; Engels, Peter; Zhang, Chuanwei; 0000 0000 3722 2361 (Zhang, C); 4042455 (Zhang, C); Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, ChuanweiThe Josephson effect is a prominent phenomenon of quantum supercurrents that has been widely studied in superconductors and superfluids. Typical Josephson junctions consist of two real-space superconductors (superfluids) coupled through a weak tunneling barrier. Here we propose a momentum-space Josephson junction in a spin-orbit coupled Bose-Einstein condensate, where states with two different momenta are coupled through Raman-assisted tunneling. We show that Josephson currents can be induced not only by applying the equivalent of "voltages," but also by tuning tunneling phases. Such tunneling-phase-driven Josephson junctions in momentum space are characterized through both full mean field analysis and a concise two-level model, demonstrating the important role of interactions between atoms. Our scheme provides a platform for experimentally realizing momentum-space Josephson junctions and exploring their applications in quantum-mechanical circuits.Item Observation of Floquet Bands in Driven Spin-Orbit-Coupled Fermi Gases(American Physical Society) Huang, L.; Peng, P.; Li, D.; Meng, Z.; Chen, L.; Qu, Chunlei; Wang, P.; Zhang, Chuanwei; Zhang, J.; 4042455 (Zhang, C); Qu, Chunlei; Zhang, ChuanweiPeriodic driving of a quantum system can significantly alter its energy bands and even change the band topology, opening a completely new avenue for engineering novel quantum matter. Although important progress has been made recently in measuring topological properties of Floquet bands in different systems, direct experimental measurement of full Floquet band dispersions and their topology change is still demanding. Here we directly measure Floquet band dispersions in a periodically driven spin-orbit-coupled ultracold Fermi gas using spin-injection radio-frequency spectroscopy. We observe that the Dirac point originating from two-dimensional spin-orbit coupling can be manipulated to emerge at the lowest or highest two dressed bands by fast modulating Raman laser frequencies, demonstrating topological change of Floquet bands. Our work will provide a powerful tool for understanding fundamental Floquet physics as well as engineering exotic topological quantum matter.Item Paths to Non-ergodic Quantum Dynamics: From Cavity QED to Strong Zero Modes(December 2022) Rahmanian Koshkaki, Saeed; Pereira, Luis Felipe; Kolodrubetz, Michael; Lv, Bing; Vandenberghe, William; Zhang, Fan; Zhang, ChuanweiRecent advances in cold atoms experiments and the development of superconducting circuits have revolutionized the way we can examine, observe and implement new physical phenomena. In such systems, we can realize new classes of quantum systems which exhibit non-equilibrium quantum phenomena. These systems have attracted mcuh attention in the past two decades as they possess new physics absent in equilibrium. Beside interesting rich physics to learn more about quantum systems, understanding non-equilibrium systems are crucial in developing future technologies such as quantum computation and communication. Given that many open questions needed to be answered in the study of non-equilibrium quantum systems, in this dissertation we will present our theoretical and numerical attempts in providing answers to some of these questions. One of the key features of the non-equilibrium system is how the dynamical properties of quantum systems cane be characterized in different conditions. Here we will present our result on two different mechanism a system can avoid ergodicity. Many-body localization (MBL) is an extension of Anderson localization to interacting systems, where adding strong enough disorder (breaking translational symmetry by adding random potential such as impurity in crystals) can impede the conductivity (system becomes insulator) in the quantum system. Most of the known MBL systems are short- range interacting particles, but in this dissertation, we will discuss MBL in the presence of coupling of the matter to cavity/circuit QED mode where the combined system becomes long-range interacting. We will study the two cases of weak coupling and strong coupling regimes and will derive the effective Hamiltonian using the high-frequency expansion for each case of coupling strength. We predict that the cavity QED has new localization behaviors such as an inversion of the mobility edge where the high-energy states are localized and low-energy states are delocalized. Also in the strong coupling limit, we observed that using the idea from coherent destruction of coupling the system can show signs of localization for photon number as low as n ∼ 2. The rest of this dissertation is devoted to understanding how a clean system (no disorder) can possess symmetry-breaking edge modes indefinitely, or for a long enough but finite time. The case with infinite lifetime edge mode is called strong mode (SM) and the case with finite lifetime edge mode is known as almost strong mode (ASM). Our system of interest is a clock Z3 model which is an extension of the Ising Z2 models. In the clock model (Baxter and modified Baxter) we found that the chirality of the interaction is essential in deriving the exact edge mode in the Hermitian model but removing the hermiticity (controlled by a parameter β), the effect of chirality on the stability of the edge mode becomes less important. We attempt to use different numerical and approximation techniques such as Krylov Hamiltonian and dynamical signature to characterize the edge mode in a Z3 model.