An analytical approach, based on the unitary transformation method, has been developed to study the effect of quantum lattice fluctuations on the ground state of an XY spin-Peierls chain, which is equivalent to the spinless Su-Schrieffer-Heeger model in h...

The three-spin chain with a Heisenberg XY interaction is simulated in a three-qubit nuclear magnetic resonance quantum computer. The evolution caused by the XY interaction is decomposed into a series of single-spin rotations and the J -coupling evolutions between the neighboring spins. The perfect state ...

A generalization of the one-dimensional frustrated quantum XY model is considered in which the inter and intra-chain coupling constants of the two infinite XY (planar rotor) chains have different strengths. The model can describe the superconductor-insula...

Explicit factorized formulas for the matrix elements (form factors) of the spin operators ?x and ?y between the eigenvectors of the Hamiltonian of the finite quantum periodic XY-chain in a transverse field were derived. The derivation is based on the relations between three models: the model of quantum XY-chain, ...

The three-spin chain with a Heisenberg XY interaction is simulated in a three-qubit nuclear magnetic resonance quantum computer. The evolution caused by the XY interaction is decomposed into a series of single-spin rotations and the J-coupling evolutions between the neighboring spins. The perfect state transfer ...

In the present paper we study forward Quantum Markov Chains (QMC) defined on a Cayley tree. Using the tree structure of graphs, we give a construction of quantum Markov chains on a Cayley tree. By means of such constructions we prove the existence of a phase transition for the XY-model on a ...

We study the disentanglement evolution of two spin qubits which interact with a general XY spin-chain environment. The dynamical process of the disentanglement is numerically and analytically investigated in the vicinity of a quantum phase transition (QPT) of the spin chain in both weak and strong coupling cases. ...

This paper studies the discord of a bipartite two-level system coupling to an XY spin-chain environment in a transverse field and investigates the relationship between the discord property and the environment's quantum phase transition. The results show that the quantum discord is also able to characterize the ...

A method for exactly diagonalizing the XY Hamiltonian of an alternating open chain of spins s = 1/2 has been proposed on the basis of the Jordan-Wigner transformation and analysis of the dynamics of spinless fermions. The multiple-quantum spin dynamics of alternating open chains at high temperatures has been ...

We investigate the propagation of information through the disordered XY model. We find that all correlations, both classical and quantum, are exponentially suppressed outside of an effective light cone whose radius grows at most logarithmically with |t|. PMID:17995284

We study the effect of Dzyaloshinskii-Moriya (DM) interaction on pairwise quantum discord, entanglement, and classical correlation in the anisotropic XY spin-half chain. Analytical expressions for both quantum and classical correlations are obtained from the spin-spin correlation functions. These pairwise ...

The complexity of representation of operators in quantum mechanics can be characterized by the operator space entanglement entropy (OSEE). We show that in the homogeneous Heisenberg XY spin 1/2 chains the OSEE for initial local operators grows at most logarithmically with time. The prefactor in front of the logarithm generally ...

The entanglement of quantum XY spin chains of arbitrary length is investigated via a recently developed global measure suitable for generic quantum many-body systems. This entanglement is determined over the phase diagram and found to exhibit rich structure. In particular, the field derivative of the entanglement ...

We investigate pairwise quantum correlation as measured by the quantum discord as well as its classical counterpart in the thermodynamic limit of anisotropic XY spin-1/2 chains in a transverse magnetic field for both zero and finite temperatures. Analytical expressions for both classical and ...

We explore the finite-temperature phase diagram of the anisotropic XY spin chain using the quantum Chernoff bound metric on thermal states. The analysis of the metric elements allows one to easily identify, in terms of different scaling with temperature, quasiclassical and quantum-critical regions. These results ...

A generalization of the one-dimensional frustrated quantum [ital XY] model is considered in which the interchain and intrachain coupling constants of the two infinite [ital XY] (planar rotor) chains have different strengths. The model can describe the superconductor to insulator transition due to charging effects ...

We find a transformation relating the one-dimensional XY spin chain and the one-dimensional quantum Ising model in a transverse magnetic field. This allows us to derive an infinite set of local conserved charges for the Ising model, which are exhibited explicitly.

Using quantization in the Fock space of operators, we compute the nonequilibrium steady state in an open Heisenberg XY spin 1/2 chain of a finite but large size coupled to Markovian baths at its ends. Numerical and theoretical evidence is given for a far-from-equilibrium quantum phase transition with the spontaneous emergence of ...

Using quantization in the Fock space of operators, we compute the nonequilibrium steady state in an open Heisenberg XY spin 1/2 chain of a finite but large size coupled to Markovian baths at its ends. Numerical and theoretical evidence is given for a far-from-equilibrium quantum phase transition with the spontaneous emergence of ...

We investigate quantum state transfer in XY spin chains and propose a recursive procedure to construct the nonuniform couplings within these chains of arbitrary length in order to achieve perfect state transfer. We show that this method is capable of finding all possible coupling schemes for perfect state transfer. ...

We study the sine-square deformed quantum XY chain with open boundary conditions in which the interaction strength at the position x in the chain of length L is proportional to the function f_x = \\sin ^2 \\big[\\frac{\\pi }{L}\\big(x-\\frac{1}{2}\\big)\\big]. The model can be mapped onto a free spinless fermion ...

We show how to implement quantum computation on a system with an intrinsic Hamiltonian by controlling a limited subset of spins. Our primary result is an efficient control sequence on a nearest-neighbor XY spin chain through control of a single site and its interaction with its neighbor. Control of an array of sites yields sufficient ...

We show how to implement quantum computation on a system with an intrinsic Hamiltonian by controlling a limited subset of spins. Our primary result is an efficient control sequence on a nearest-neighbor XY spin chain through control of a single site and its interaction with its neighbor. Control of an array of sites yields sufficient ...

By introducing the Dzyaloshinsky-Moriya (DM) interaction, the Loschmidt Echo (LE) of a quantum system consisting of a central spin and its surrounding environment characterized by an XY spin chain was investigated. The analytical expression of the LE was obtained. The effects of magnetic field, DM interaction, spin ...

We develop a trap-size scaling theory for trapped particle systems at quantum transitions. As a theoretical laboratory, we consider a quantum XY chain in an external transverse field acting as a trap for the spinless fermions of its quadratic Hamiltonian representation. We discuss trap-size scaling at the Mott ...

It is well known that the dynamics of a quantum system is always nonadiabatic in passage through a quantum critical point and the defect density in the final state following a quench shows a power-law scaling with the rate of quenching. However, we propose here a possible situation where the dynamics of a quantum system in passage ...

High-fidelity quantum computation and quantum state transfer are possible in short spin chains. We exploit a system based on a dispersive qubit-boson interaction to mimic XY coupling. In this model, the usually assumed nearest-neighbor coupling is no longer valid: all the qubits are mutually coupled. We analyze the ...

We use the density matrix renormalization group method to investigate the role of longitudinal quantized phonons on the Peierls transition in the spin-Peierls model. For both the XY and Heisenberg spin-Peierls model we show that the staggered phonon order parameter scales as sqrt[lambda] (and the dimerized bond order scales as lambda) as lambda-->0 (where lambda is the ...

We study the quality of state and entanglement transmission through quantum channels described by spin chains varying both the system parameters and the initial state of the channel. We consider a vast class of one-dimensional many-body models which contains some of the most relevant experimental realizations of quantum data buses. In ...

A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic ...

We present results of a quantum Monte Carlo study of a quasi one-dimensional XY spin model coupled to quantum phonons. We compare different updating techniques for the Stochastic Series Expansion method and present autocorrelation time data. We are able to reduce autocorrelation times by using loop update techniques for both spin and ...

We present results of a quantum Monte Carlo study of a quasi one-dimensional XY spin model coupled to quantum phonons. We compare different updating techniques for the Stochastic Series Expansion method and present autocorrelation time data. We are able to reduce autocorrelation times by using loop update techniques for both spin and ...

A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic ...

We explore the robustness of universal dynamical scaling behavior in a quantum system near criticality with respect to initialization in a large class of states with finite energy. By focusing on a homogeneous XY quantum spin chain in a transverse field, we characterize the nonequilibrium response under adiabatic ...

We compute concurrence and negativity as measures of two-spin entanglement generated by a power-law quench (characterized by a rate ?-1 and an exponent ? ) which takes an anisotropic XY chain in a transverse field through a quantum critical point (QCP). We show that only spins separated by an even number of lattice spacings get ...

We study decoherence induced on a two-level system coupled to a one-dimensional quantum spin chain. We consider the cases where the dynamics of the chain is determined by the Ising, XY, or Heisenberg exchange Hamiltonian. This model of quantum baths can be of fundamental importance for the ...

Exactly solvable models provide an opportunity to study different aspects of reduced quantum dynamics in detail. We consider the reduced dynamics of a single spin in finite XX and XY spin 1/2 chains. First we introduce a general expression describing the evolution of the reduced density matrix. This expression proves to be tractable ...

In this paper, we consider the generation of a three-qubit Greenberger-Horne-Zeilinger-like thermal state by applying the entanglement swapping scheme of Zukowski et al. [Ann. N. Y. Acad. Sci. 755, 91 (1995)] to three pairs of two-qubit Heisenberg XY chains. The quality of the resulting three-qubit entanglement is studied by analyzing the teleportation ...

Motivated by the idea of entanglement loss along renormalization group flows, analytical majorization relations are proven for the ground state of (1+1)-dimensional conformal field theories. For any of these theories, majorization is proven to hold in the spectrum of the reduced density matrices in a bipartite system when changing the size L of one of the subsystems. Continuous majorization along ...

Motivated by the idea of entanglement loss along renormalization group flows, analytical majorization relations are proven for the ground state of (1+1) -dimensional conformal field theories. For any of these theories, majorization is proven to hold in the spectrum of the reduced density matrices in a bipartite system when changing the size L of one of the subsystems. Continuous majorization ...

We explore the relation between entanglement entropy of quantum many-body systems and the distribution of corresponding, properly selected, observables. Such a relation is necessary to actually measure the entanglement entropy. We show that, in general, the Shannon entropy of the probability distribution of certain symmetry observables gives a lower bound to the entropy. In ...

It has recently been shown that one can perform quantum computation in a Heisenberg chain in which the interactions are always on, provided that one can abruptly tune the Zeeman energies of the individual (pseudo)spins. Here we provide a more complete analysis of this scheme, including several generalizations. We generalize the interaction to an ...

Atom counting theory can be used to study the role of thermal noise in quantum phase transitions and to monitor the dynamics of a quantum system. We illustrate this for a strongly correlated fermionic system, which is equivalent to an anisotropic quantum XY chain in a transverse field and can ...

The authors present a detailed analysis of the structure of the conservation laws in quantum integrable chains of the XYZ-type and in the Hubbard model. The essential tool for the former class of models is the boost operator, which provides a recursive way of calculating the integrals of motion. With its help, they establish the general form of the XYZ ...

In the particular case of the asymmetric XY model an explicit form for the operator corresponding to Baxter's quantum number n is obtained. It is shown ihat this operator is closely associated with a transformation of spin operators which converts the asymmetric XY Hamiltonian into a symmetric XY ...

We establish a quantitative relationship between the entanglement content of a single quantum chain at a critical point and the corresponding entropy of entanglement. We find that, surprisingly, the leading critical scaling of the single-copy entanglement with respect to any bipartitioning is exactly one-half of the entropy of entanglement, in a general ...

Spin wave theory is successfully applied to study the ground state of the quantum XY Hamiltonian. It is found that a judicious choice of the quantized spin axis removes difficulties of previous applications. Results for the simplest one-, two-, and three-...

We study the dynamics of a Heisenberg XY spin chain with an unknown state coded into one qubit or a pair of entangled qubits, with the rest of the spins being in a polarized state. The time evolution involves magnon excitations, and through them the entanglement is transported across the channel. For a large number of qubits, explicit formulas for the ...

We investigate the dissipative dynamics of a quantum critical system in contact with a thermal bath, focusing on the response of the system to a sudden change of the bath temperature, in analogy to studies of aging. The specific example of the XY model in a transverse magnetic field whose spins are locally coupled to a set of bosonic baths is considered. ...

The equilibration dynamics of a closed quantum system is encoded in the long-time distribution function of generic observables. In this Letter we consider the Loschmidt echo generalized to finite temperature, and show that we can obtain an exact expression for its long-time distribution for a closed system described by a quantum XY ...

This paper analyzes the decoherence induced on a single qubit by the interaction with a spin chain with nontrivial internal dynamics (XY-type interactions). The aim of the paper is to study the existence and properties of the so-called universal regime, in which the decoherence time scale becomes independent of the strength of the coupling with the ...

The equilibration dynamics of a closed quantum system is encoded in the long-time distribution function of generic observables. In this Letter we consider the Loschmidt echo generalized to finite temperature, and show that we can obtain an exact expression for its long-time distribution for a closed system described by a quantum XY ...

Part I studies the effect of quantum fluctuations of the phase on the low temperature behavior of two models of Josephson junction chains with Coulomb interactions taken into account. The first model, which represents a chain of junctions close to a ground plane, is the Hamiltonian version of the two-dimensional XY ...

We promote use of the geometric entropy formula derived by Holzhey et al. from conformal field theory, S{sub l}{approx}(c/3)log(sin {pi}l/N), to identify critical regions in zero temperature 1D quantum systems. The method is demonstrated on a class of one-dimensional XY and XYZ spin-(1/2) chains, where the critical regions and their ...

A regularization method is presented to deduce dynamic correlation functions from exact diagonalization calculations. It is applied to dimer-dimer correlation functions in quantum spin chains relevant for the description of spin-Peierls systems. Exact results for the XY model are presented. The analysis draws into doubt that the ...

The concepts of concurrence and mode concurrence are the measures of entanglement for spin-1/2 and spinless fermion systems, respectively. Based on the Jordan-Wigner transformation, any spin-1/2 system is always associated with a fermion system (called the counterpart system). A comparison of concurrence and mode concurrence can be made with the aid of Marshall's sign rule for the ground ...

Nonlocality and quantum entanglement constitute two special features of quantum systems of paramount importance in quantum-information theory (QIT). Essentially regarded as identical or equivalent for many years, they constitute different concepts. Describing nonlocality by means of the maximal violation of two Bell inequalities, we ...

We study heat transport in a one-dimensional inhomogeneous quantum spin-1/2 system. It consists of a finite-size XX spin chain coupled at its ends to semi-infinite XX and XY chains at different temperatures, which play the role of heat and spin reservoirs. After using the Jordan-Wigner transformation we map ...

We consider the general {Z}_2 -symmetric free-fermion model on the finite periodic lattice, which includes as special cases the Ising model on the square and triangular lattices and the {Z}_n -symmetric BBS ?(2)-model with n = 2. Translating Kaufman's fermionic approach to diagonalization of Ising-like transfer matrices into the language of Grassmann integrals, we determine the transfer matrix ...

Motivated by recent development in quantum entanglement, we study relations among concurrence C, SU{sub q}(2) algebra, quantum phase transition and correlation length at the zero temperature for the XXZ chain. We find that at the SU(2) point, the ground state possesses the maximum concurrence. When the anisotropic parameter {delta} is ...

In this work we investigate the equilibration dynamics after a sudden Hamiltonian quench of a quantum spin system initially prepared in a thermal state. To characterize the equilibration we evaluate the Loschmidt echo, a global measure for the degree of distinguishability between the initial and time-evolved quenched states. We present general results valid for small quenches ...

We study adiabatic quantum quenches across a quantum multicritical point (MCP) using a quenching scheme that enables the system to hit the MCP along different paths. We show that the power-law scaling of the defect density with the rate of driving depends non-trivially on the path, i.e., the exponent varies continuously with the parameter ? that defines ...

The spin-1/2 chain with XY anisotropic coupling in the plane and the XX isotropic dimerized chain are shown to be equivalent in the bulk. For finite systems, we prove that the equivalence is exact in given parity sectors, after taking care of the precise boundary conditions. The proof is given constructively by finding unitary ...

This paper demonstrates that multipartite Bell-inequality violations can be fully destroyed in a finite time in three-qubit states coupled to a general XY spin-chain with a three-site interaction environment. The Mermin�Ardehali�Belinksii�Klyshko inequality is used to detect the degree of nonlocality, as measured by the extent of their violations. ...

We investigate the entanglement dynamics of two interacting qubits in a spin environment, which is described by an XY model with Dzyaloshinsky-Moriya (DM) interaction. The competing effects of environmental noise and interqubit coupling on entanglement generation for various system parameters are studied. We find that the entanglement generation is suppressed remarkably in ...

By use of mainly numerical methods, we investigate the ground-state phase diagram of an S = 2 quantum spin chain with the XXZ and on-site anisotropies described by Script H = ?j(SjxSj+1x + SyjSyj+1 + ?SzjSzj+1 + D ?j(Szj)2, where ? denotes the XXZ anisotropy parameter of the nearest-neighbor interactions and D the on-site anisotropy parameter. In the phase ...

We consider an infinite one-dimensional anisotropic XY spin chain with a nearest-neighbor time-dependent Heisenberg coupling J(t) between the spins in presence of a time-dependent magnetic field h(t). We discuss a general solution for the system and present an exact solution for particular choice of J and h of practical interest. We investigate the ...

In land plants, xyloglucans (XyGs) tether cellulose microfibrils into a strong but extensible cell wall. The MUR2 and MUR3 genes of Arabidopsis encode XyG-specific fucosyl and galactosyl transferases, respectively. Mutations of these genes give precisely altered XyG structures missing one or both of these subtending sugar residues. ...

We consider an inhomogeneous quantum phase transition across a multicritical point of the XY quantum spin chain. This is an example of a Lifshitz transition with a dynamical exponent z=2. Just like in the case z=1 considered by Dziarmaga and Rams (2010 New J. Phys. 12 055007), when a critical front propagates much ...

Combining scanning gate microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of the electron probability density |Psi|(2)(x,y) in embedded mesoscopic quantum rings. The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wave ...

. We must find $ x,y \\in \\mathbb{F}_q$ such that $ a f^x + b g^y = c$ . As shown in [111], quantum computers can solve this problem in $ O(q^{3/8})$ time whereas the best...

A one-dimensional polymer, polyacetylene (CH)sub(x), is studied as a model of quantum statistical mechanics. The system is equivalent to a 1 D quantum XY-model interacting with unbounded bosonic spins (=phonon fields). It is established that the XY-spin c...

For computation of the equilibrium statistical properties of finite spin-1/2 XY chains with Dzyaloshinskii-Moriya interaction the suggested earlier approach (JMMM 140-144 (1995) 1623) is generalized. It is applied for calculation of transverse dynamical s...

Evidence for the existence of one-dimensional XY antiferromagnetic chains in Cs sub 2 CoCl sub 4 has been given by the neutron scattering measurements. This compound also provides a simple model of order in the frustrated system. (ERA citation 07:057474)

Based on the iSWAP gate generated from the XY interaction between solid-state qubits, we present an efficient quantum circuit for the implementation of discrete quantum Fourier transform. The relatively cumbersome and expensive controlled-Rk gate and SWAP gate operations required for implementing discrete quantum ...

A quantum chain of limiting quantum yield of about 1,000 occurs upon direct or sensitized excitation of tetramethyl-1,2-dioxetane. (Author)

We derive a general relation between the nonanalyticities of the ground state energy and those of a subclass of the multipartite generalized global entanglement (GGE) measure defined by de Oliveira et al. [Phys. Rev. A 73, 010305(R) (2006)PLRAAN1050-294710.1103/PhysRevA.73.010305] for many-particle systems. We show that GGE signals both a critical point location and the order of a ...

The author proposes a new Monte Carlo method for calculating eigenvalues of transfer matrices leading to free energies and to correlation lengths of classical and quantum many-body systems. Generally, this method can be applied to the calculation of the maximum eigenvalue of a nonnegative matrix A such that all the matrix elements of A[sup k] are strictly positive for an ...

We propose a new Monte Carlo method for calculating eigenvalues of transfer matrices leading to free energies and to correlation lengths of classical and quantum many-body systems. Generally, this method can be applied to the calculation of the maximum eigenvalue of a nonnegative matrix � such that all the matrix elements of �k are strictly positive for an integer k. This ...

Quantum many-body models describing natural systems or materials and physical systems assembled piece by piece in the laboratory for the purpose of realizing quantum information processing share an important feature: intricate correlations that originate from the coherent interaction between a large number of constituents. In recent years it has become ...

... Accession Number : AD0630456. Title : QUANTUM MECHANICS OF HO2. IV. CHAIN PROGRAM. Descriptive Note : Research rept.,. ...

We performed electric and thermoelectric transport measurements of bilayer graphene in a magnetic field up to 15 Tesla. The transverse thermoelectric conductivity ?xy, determined from four transport coefficients, attains a peak value of ?xy, peak whenever chemical potential lies in the center of a Landau level. The temperature dependence of ...

Exact analytic calculations in spin-1/2 XY chains show the presence of long-time tails in the asymptotic dynamics of spatially inhomogeneous excitations. The decay of inhomogeneities for t-->?, is given in the form of a power law (t/?Q)-?Q, where the relaxation time ?Q and the exponent ?Q depend on the wave vector Q, characterizing the spatial ...

Recently, field-induced phenomena in quantum spin systems have attracted considerable interest. Gapped one-dimensional (1D) spin systems with a spin value S=1 subject to an external magnetic field strong enough to close the gap (Hc) are driven into a new phase. Spin excitations in this field-induced phase have been studied by experiments on a uniform S=1 antiferromagnetic spin ...

The superfluid transition in liquid He4 filled in Gelsil glass observed in recent experiments is discussed in the framework of quantum critical phenomena. We show that quantum fluctuations of phase are indeed important in the experimentally studied temperature range owing to the small pore size of Gelsil, in contrast to He4 filled in previously studied ...

The Berezinskii-Kosterlitz-Thouless (BKT) phase transition is peculiar of two-dimensional magnetic systems with easy-plane anisotropy. Their prototype is the classical planar (or XY) model, that neglects the role of the out-of-plane spin component. The la...

... Subject Categories : NUCLEAR PHYSICS & ELEMENTARY PARTICLE PHYSICS QUANTUM THEORY AND RELATIVITY. ...

This paper considers a large class of quantum spin chains, whose Hamiltonians commute with generators of a quantum algebra and which are integrable. The authors argue that the corresponding transfer matrices also commute with the quantum algebra. For the spin a A{sub 1}{sup (1)} chain, we show ...

Xyloglucan (XyG) is a load-bearing primary wall component in dicotyledonous and non-graminaceous monocotyledonous plants. XyG fucosyltransferase (FUTase), encoded by the Arabidopsis gene AtFUT1, directs addition of fucose (Fuc) residues to terminal galactose residues on XyG side chains. Reverse ...

We present a supersymmetric modification of the [ital d]-dimensional quantum rotor model whose ground state is exactly soluble. The model undergoes a vortex-binding transition from insulator to metal as the rotor coupling is varied. The Hamiltonian contains three-site terms which are relevant: they change the universality class of the transition from that of the ([ital d]+1)- ...

A quantum Hamiltonian formalism is developed for weakly anisotropic Heisenberg (O(3)) and planar (O(2)) ferromagnetic classical spin systems in one dimension. This formalism is then used to derive explicit formulas for the Heisenberg-Ising, Heisenberg-XY, and XY-Ising crossovers at low temperatures. This approach gives the correct ...

The dynamics of two spins-1/2 interacting with a spin-bath via the quantum Heisenberg x-y coupling is studied. The purity, z-component summation and the concurrence of the central subsystem are determined by the Laguerre polynomial scheme. It is found that (i) at a low temperature, the uncoupled subsystem in a product state can be entangled by the bath, ...

We predict and theoretically investigate the new coherent effect of nonlinear quantum optics�spatial propagation of Rabi oscillations (Rabi waves) in one-dimensional quantum dot (QD) chain. QD chain is modeled by the set of two-level quantum systems with tunnel coupling between neighboring ...

The halogen bonding of furan???XY and thiophene???XY (X=Cl, Br; Y=F, Cl, Br), involving ?- and ?-type interactions, was studied by using MP2 calculations and quantum theory of "atoms in molecules" (QTAIM) studies. The negative electrostatic potentials of furan and thiophene, as well as the most positive electrostatic potential ...

An open ended spin chain can serve as a quantum data bus for the coherent transfer of quantum state information. In this paper, we investigate the efficiency of such quantum spin channels which work in a decoherence environment. Our results show that the decoherence will significantly reduce the fidelity of ...

We propose loading trapped ions into microtraps formed by an optical lattice. For harmonic microtraps, the Coulomb coupling of the spatial motions of neighboring ions can be used to construct a broad class of effective short-range Hamiltonians acting on an internal degree of freedom of the ions. For large anharmonicities, on the other hand, the spatial motion of the ions itself represents a ...

We study the optical Hall conductivity ?xy(?F, ?) in two-dimensional electron gas (2DEG) and in graphene in the quantum Hall regime, which is measurable by the Faraday rotation. It was previously demonstrated that both conductivities retain their plateau structure at finite frequency, up to the optical frequency regime. Physically, the robustness of the ...

We present a general formulation of Floquet states of periodically time-dependent open Markovian quasifree fermionic many-body systems in terms of a discrete Lyapunov equation. Illustrating the technique, we analyze periodically kicked XY spin-(1)/(2) chain which is coupled to a pair of Lindblad reservoirs at its ends. A complex phase diagram is reported ...

The entanglement dynamics of three-qubit states coupled to a general XY spin-chain with a three-site interaction environment is investigated. By using negativity as entanglement measure, we find that the entanglement evolution depends on not only the system-environment couplings but also the strength of three-site interaction. In the strong-coupling ...

A chain of interacting spin behaves like a quantum mediator (quantum link), which allows two distant parties that control the ends of the chain to exchange quantum messages. We show that over repeated uses without resetting the study of a quantum link can be connected to ...

We apply quantum control techniques to a long spin chain by acting only on two qubits at one of its ends, thereby implementing universal quantum computation by a combination of quantum gates on these qubits and indirect swap operations across the chain. It is shown that the control sequences ...

Using an NMR quantum computer, we experimentally simulate the quantum phase transition of a Heisenberg spin chain. The Hamiltonian is generated by a multiple-pulse sequence, the nuclear-spin system is prepared in its (pseudopure) ground state, and the effective Hamiltonian varied in such a way that the Heisenberg ...

Using mainly numerical methods, we investigate the ground-state phase diagram of the S = 2 quantum spin chain described by \\mathcal{H} = \\sumj(SjxSj+1x + SjySj+1y + ? SjzSj+1z) + D \\sumj(Sjz)2, where ? denotes the XXZ anisotropy parameter of the nearest-neighbor interactions and D the on-site anisotropy parameter. We restrict ourselves to the case of ?? ...

We propose a matrix product state (MPS) formulation to calculate thermodynamic quantities of one dimensional (1D) quantum systems. The maximum-eigenvalue eigenstate of the quantum transfer matrix is represented as the product of local matrices, which are obtained by the DMRG method for the two dimensional (2D) classical system mapped from the original 1D ...

The existence of quantum spin liquids was first conjectured by Pomeranchuk some 70�years ago, who argued that frustration in simple antiferromagnetic theories could result in a Fermi-liquid-like state for spinon excitations. Here we show that a simple quantum spin model on a honeycomb lattice hosts the long sought for Bose metal with a clearly ...

The existence of quantum spin liquids was first conjectured by Pomeranchuk some 70 years ago, who argued that frustration in simple antiferromagnetic theories could result in a Fermi-liquid-like state for spinon excitations. Here we show that a simple quantum spin model on a honeycomb lattice hosts the long sought for Bose metal with a clearly identifiable ...

A system of trapped ions under the action of off-resonant standing waves can be used to simulate a variety of quantum spin models. In this work, we describe theoretically quantum phases that can be observed in the simplest realization of this idea: quantum Ising and XY models. Our numerical calculations with the ...

In this work, we examine the dependence of the fluorescence quantum yield of water-soluble CdSe/ZnS quantum dots on the local environment. The hydrophobicity of the local environment was modified by using different alkyl chain lengths in a set of oligo-ethylene glycols. Our results show that the quantum yield of ...

The electronic structures of cubic InGaN systems are calculated using an atomistic empirical pseudopotential method. Two extreme cases are studied. One is a pure InN quantum dot embedded in a pure GaN matrix, another is a pure In{sub x}Ga{sub 1-x}N alloy without clustering. We find hole localizations in both cases. The hole wave function starts to be localized as soon as a few ...

... 1. Title: Quantum Dynamics of Shock Waves in Molecular ... developed and applied to model harmonic and cubic ... a linear chain of Morse oscillators; (2 ...

We present large-scale numerical simulations of several spin-1/2 XY models with four-site ring exchange, in the general class of the so-called J-K model. The Stochastic Series Expansion quantum Monte Carlo method employed in the simulations is described in detail. Physical results for ground state phases and phase transitions are presented for the ...

We reveal from numerical study that the optical Hall conductivity sigma(xy)(omega) has a characteristic feature even in the ac ( approximately THz) regime in that the Hall plateaus are retained both in the ordinary two-dimensional electron gas and in graphene in the quantum Hall regime, although the plateau height is no longer quantized in ac. In graphene ...

We investigate the critical parameters of an order-disorder quantum phase transition in the spin-� J-J ' Heisenberg and XY antiferromagnets on a square lattice. Based on the excitation gaps calculated by the exact diagonalization technique for systems up to 32 spins and finite-size scaling analysis we estimate the critical couplings and exponents of the ...

The ?=0 quantum Hall state in a defect-free graphene sample is studied within the framework of the quantum Hall ferromagnetism. Starting from the low-energy electron Hamiltonian, in which all allowed by symmetry sublattice- and valley-anisotropic terms due to the Coulomb and leading electron-phonon interactions are taken into account, the energy functional ...

We study entanglement properties of all eigenstates of the Heisenberg XXX model, and find that the entanglement and mixedness for a pair of nearest-neighbor qubits are completely determined by the corresponding eigenenergies. Specifically, the negativity of the eigenenergy implies pairwise entanglement. From the relation between entanglement and eigenenergy, we obtain finite-size behaviors of the ...

We investigate the relation between the diagonal (?(xx)) and off-diagonal (?(xy)) components of the conductivity tensor in the quantum Hall system. We calculate the conductivity components for a short-range impurity potential using the linear response theory, employing an approximation that simply replaces the self-energy by a constant value [Formula: see ...

We investigate the relation between the diagonal (?xx) and off-diagonal (?xy) components of the conductivity tensor in the quantum Hall system. We calculate the conductivity components for a short-range impurity potential using the linear response theory, employing an approximation that simply replaces the self-energy by a constant value -\\rmi \\hbar /(2 ...

The physics of quantum walks on graphs is formulated in Hamiltonian language, both for simple quantum walks and for composite walks, where extra discrete degrees of freedom live at each node of the graph. It is shown how to map between quantum walk Hamiltonians and Hamiltonians for qubit systems and quantum ...

We present numerical evidence that quantum fluctuations can produce a symmetric ground-state in the double-well chain, restoring the symmetry that is broken classically. In particular, we present the phase diagram for this model that shows the symmetry re...

At the critical point the spectra of quantum chains with periodic and twisted boundary conditions are described by irreducible representations of two Virasoro algebras with the same central charge. We show that in the case of free boundary conditions, the...

We conjecture the operator content for the n-states quantum chains (ngreater than or equal to 5) in the domains of the coupling constants where the central charge of the Virasoro algebra is equal to one. Free boundary conditions as well as boundary condit...

I argue that quantum theory can, and in fact must, be applied to the Universe as a whole. After a general introduction, I discuss two concepts that are essential for my chain of arguments: the universality of quantum theory and the emergence of classical behaviors by decoherence. A further motivation is given by the open problem of ...

Transferring quantum information between two qubits is a basic requirement for many applications in quantum communication and quantum-information processing. In the iterative quantum-state transfer proposed by Burgarth et al. [Phys. Rev. A 75, 062327 (2007)], this is achieved by a static spin ...

Quantum state transfer is an important task in quantum information processing. It is known that one can engineer the couplings of a one-dimensional spin chain to achieve the goal of perfect state transfer. To leverage the value of these spin chains, a spin star is potentially useful for connecting different parts ...

We define a new set of excitations in the XY model which we call ''fractional vortices.'' In the frustrated XY model containing {pi} bonds, we make the ansatz that the ground state configurations can be characterized by pairs of oppositely charged fractional vortices. For a chain of {pi} bonds, the ...

... CONSISTENCY, GAMMA RAYS, RUSSIA, QUANTUM ELECTRONICS, NUCLEAR ENERGY, CHAIN REACTIONS, NUCLEAR PUMPING. ...

... IN A CANONICAL GROUP CHAIN WITH ... OPERATORS(MATHEMATICS), *GROUPS(MATHEMATICS ... VECTOR ANALYSIS, QUANTUM THEORY, N ...

We show that the set of observables \\{Z? X, (\\cos?) X + (sin?) Y all ? in [0,2?)\\} with one ancillary qubit is universal for quantum computation. The set is simpler than a previous one in the sense that one-qubit projective measurements described by the observables in the set are ones only in the (X,Y) plane of the Bloch sphere. The proof of the ...

We introduce an approach to quantum cloning based on spin networks and we demonstrate that phase covariant cloning can be realized using no external control but only with a proper design of the Hamiltonian of the system. In the 1{yields}2 cloning we find that the XY model saturates the value for the fidelity of the optimal cloner and gives values ...

We introduce an approach to quantum cloning based on spin networks and we demonstrate that phase covariant cloning can be realized using no external control but only with a proper design of the Hamiltonian of the system. In the 1?2 cloning we find that the XY model saturates the value for the fidelity of the optimal cloner and gives values comparable ...

We show that as the number of vortices in a three dimensional Bose-Einstein condensate increases, the system reaches a "quantum Hall" regime where the density profile is a Gaussian in the xy plane and an inverted parabolic profile along z. The angular momentum of the system increases as the vortex lattice shrinks. However, Coriolis force prevents the unit ...

It is known from the analysis of the density matrix for bipartite systems that the quantum discord (as a measure of quantum correlations) depends on the particular subsystem chosen for the projective measurements. We study asymmetry of the discord in a simple physical model of two spin-1/2 particles with the dipole-dipole interaction governed by the ...

By using the method of exact diagonalization, we investigate the quantum correlation measured by quantum discord of the dimerized spin chain at both zero and finite temperatures. The results disclose that the quantum discord is robust at any finite parameter ? and temperature T, in contrast to entanglement which ...

To investigate the onset of thermal rectification in graded mass systems, we study the classic and quantum self-consistent harmonic chain of oscillators. We show that rectification is absent in the classic, but present in the quantum chain. We note the ingredient of rectification, and its existence in this simple ...

We numerically demonstrate the formation of quantum flexible chains in a gas of polar molecules confined into a stack of N 1d or 2d optical lattice layers, and with dipole moment aligned perpendicularly to the layers. Molecules interact via dipole-dipole interaction. Ab initio simulations of a single chain pinned at one end reveal ...

Discrete sine-Gordon (SG) chains are studied with path-integral molecular dynamics. Chains commensurate with the substrate show the transition from pinning to quantum creep at bead masses slightly larger than in the continuous SG model. Within the creep regime, a field-driven transition from creep to complete depinning is identified. ...

We study the effect of thermal fluctuations in a recently proposed protocol for transmission of unknown quantum states through quantum spin chains. We develop a low-temperature expansion for general spin chains. We then apply this formalism to study exactly thermal effects on short spin chains ...

Control of the transfer of quantum information encoded in quantum wave packets moving along a spin chain is demonstrated. Specifically, based on a relationship with control in a paradigm of quantum chaos, it is shown that wave packets with slow dispersion can automatically emerge from a class of initial ...

We present results from a quantum and semiclassical theoretical study of the \\rho_{xy} and \\rho_{xx} resistivities of a high mobility 2-D electron gas in the presence of a dilute random distribution of tubes with magnetic flux \\Phi and radius R, for arbitrary values of k_f R and F=e\\Phi/h. We report on novel Aharonov-Bohm type oscillations in ...

We report recent progress in determining the global behavior of the two-dimensional electron gas in a high magnetic field. Specifically, we have: (i) derived a law of corresponding states which allows us to construct a global phase diagram and calculate many interrelations between transport coefficients; (ii) derived a ``selection rule'' governing the allowed continuous transitions between pairs ...

We report on the unusual nature of the nu=0 state in the integer quantum Hall effect (QHE) in graphene and show that electron transport in this regime is dominated by counterpropagating edge states. Such states, intrinsic to massless Dirac quasiparticles, manifest themselves in a large longitudinal resistivity rho(xx) > or approximately h/e(2), in striking contrast to ...

In temporal gauge A=0 the 3d Chern-Simons theory acquires quadratic action and an ultralocal propagator. This directly implies a 2d R-matrix representation for the correlators of Wilson lines (knot invariants), where only the crossing points of the contours projection on the xy plane contribute. Though the theory is quadratic, P-exponents remain non-trivial operators and ...

In this work, we investigate the effects of the Berry phase 2 ?? on the critical properties of XY quantum-rotors that undergo a percolation transition. This model describes a variety of randomly-diluted quantum systems, such as interacting bosons coupled to a particle reservoir, quantum planar antiferromagnets ...

We study the von Neumann block entropy in the Kondo necklace model for different anisotropies {eta} in the XY interaction between conduction spins using the density matrix renormalization group method. It was found that the block entropy presents a maximum for each {eta} considered, and, comparing it with the results of the quantum criticality of the model ...

and aperiodic finite Markov chain with stationary distribution , i.e. P = . Given an > 0, the mixing time tmixA note on adiabatic theorem for Markov chains and adiabatic quantum computation Yevgeniy Kovchegov Abstract We derive an adiabatic theorem for Markov chains using well known facts about mixing

We combine nanoimprint lithography and molecular beam epitaxy for the site-controlled growth of InAs quantum dot chains on GaAs(100) substrates. We study the influence of quantum dot growth temperature and regrowth buffer thickness on the formation of the quantum dot chains. In particular, we ...

This paper deals with the problem of estimating the coupling constant ? of a mixing quantum Markov chain. For a repeated measurement on the chain�s output we show that the outcomes� time average has an asymptotically normal (Gaussian) distribution, and we give the explicit expressions of its mean and variance. In particular, we ...

We study the transfer of a quantum state through a Heisenberg spin-1 chain prepared in its ground state. We characterize the efficiency of the transfer via the fidelity of retrieving an arbitrarily prepared state and also via the transfer of quantum entanglement. The Heisenberg spin-1 chain has a very rich ...

We study polar molecules in a stack of strongly confined pancake traps. When dipole moments point perpendicular to the planes of the traps and are sufficiently strong, the system is stable against collapse but attractive interaction between molecules in different layers leads to the formation of dipolar chains, analogously to the chaining phenomenon in ...

We study polar molecules in a stack of strongly confined pancake traps. When dipole moments point perpendicular to the planes of the traps and are sufficiently strong, the system is stable against collapse but attractive interaction between molecules in different layers leads to the formation of dipolar chains, analogously to the chaining phenomenon in ...

We extend the program initiated by T. Werlang [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.105.095702 105, 095702 (2010)] in several directions. Firstly, we investigate how useful quantum correlations, such as entanglement and quantum discord, are in the detection of critical points of quantum phase transitions when the system ...

We describe a numerical scheme for exactly simulating the heat current behavior in a quantum harmonic chain with self-consistent reservoirs. Numerically exact results are compared to classical simulations and to the quantum behavior under the linear-response approximation. In the classical limit or for small temperature biases our ...

We describe a numerical scheme for exactly simulating the heat current behavior in a quantum harmonic chain with self-consistent reservoirs. Numerically exact results are compared to classical simulations and to the quantum behavior under the linear-response approximation. In the classical limit or for small temperature biases our ...

Transmitting quantum states and entanglement through quantum channels is one of the key requirements for the development of quantum computation. Quantum discord has received much attention in quantum computation. We transfer quantum discord through two parallel XXZ spin ...

We study quantum chains formed in a gas of polar bosonic molecules confined in a stack of N identical one- and two-dimensional optical lattice layers, with molecular dipole moments aligned perpendicularly to the layers. Quantum Monte Carlo simulations of a single chain reveal its quantum ...

We investigate the entanglement of a two-qubit anisotropic Heisenberg XY chain in thermal equilibrium at temperature T in the presence of an external magnetic field B along the z-axis. By means of the combined influences of anisotropic interactions and a magnetic field B, one is able to produce entanglement for any finite T, by adjusting the magnetic field ...

Establishment of the steroid-producing Leydig cell lineage is an event downstream of Sry that is critical for masculinization of mammalian embryos. Neither the origin of fetal Leydig cell precursors nor the signaling pathway that specifies the Leydig cell lineage is known. Based on the sex-specific expression patterns of Desert Hedgehog (Dhh) and its receptor Patched 1 (Ptch1) in ...

The scalability of solid-state quantum computation relies on the ability of connecting the qubits to the macroscopic world. Quantum chains can be used as quantum wires to keep regions of external control at a distance. However, even in the absence of external noise their transfer fidelity is too low to assure ...

We discuss a simple search problem which can be pursued with different methods, either on a classical or on a quantum basis. The system is represented by a chain of trapped ions. The ion to be searched for is a member of that chain, consisting, however, of an isotopic species different from the others. It is shown that classical ...

We examine certain classical continuum long wave-length limits of prototype integrable quantum spin chains. We define the corresponding construction of classical continuum Lax operators. Our discussion starts with the XXX chain, the anisotropic Heisenberg model and their generalizations and extends to the generic isotropic and ...

The Arabidopsis (Arabidopsis thaliana) root epidermal bulger1-1 (reb1-1) mutant (allelic to root hair defective1 [rhd1]) is characterized by a reduced root elongation rate and by bulging of trichoblast cells. The REB1/RHD1 gene belongs to a family of UDP-D-Glucose 4-epimerases involved in the synthesis of D-Galactose (Gal). Our previous study showed that certain arabinogalactan protein epitopes ...

The Arabidopsis (Arabidopsis thaliana) root epidermal bulger1-1 (reb1-1) mutant (allelic to root hair defective1 [rhd1]) is characterized by a reduced root elongation rate and by bulging of trichoblast cells. The REB1/RHD1 gene belongs to a family of UDP-d-Glucose 4-epimerases involved in the synthesis of d-Galactose (Gal). Our previous study showed that certain arabinogalactan protein epitopes ...

The classical ground state of a flexible chain molecule (polymer) is well known to be simple, just a straight line. Here we consider quantum fluctuations of flexible chains. In their presence, the straight ground (zero-temperature) state becomes rough, whereas the Hookean, linear elastic theory breaks down: For a weak tensile force ...

We use a spin-coherent representation to derive the spectrum of nonlinear excitations in a spin-S quantum ferromagnetic Heisenberg chain in the continuum limit. Quantum effects split the semiclassical spectrum into two branches: a lower branch of spin-wave-like, large-width solitary waves with negligible quantum ...

By using the concept of concurrence, we study pairwise entanglement between the two end spins in the open-ended Heisenberg XXX and XY chains up to ten spins. The results show that by introducing two boundary impurities, one can obtain maximum entanglement at the limit of the impurity parameter |J1| ? J for the even-number qubits. When |J1/J| > 0, the ...

In this paper the entanglement and quantum phase transition of the anisotropic spin-1/2 XY model are studied by using the quantum renormalization-group method. By solving the renormalization equations, we get the trivial and nontrivial fixed points, which correspond to the phase of the system and the critical point, respectively. The ...

vortex theory, the XY ordered phase is simply characterized as a dual `para- magnet' where 1,2 = 0 is preserved. Note the remarkable complementarity between the description of the phases in this dual theory correspondence should be addressed; E-mail: senthil@mit.edu. September 22, 2003 The theory of second order phase

. Bassi 6, I-27100 Pavia, Italy and INFM, Pavia, Italy (Received July 10, 2002) I study the thermodynamic antiferromagnet in a uniform magnetic #28;eld), making use of the continuous-time Quantum Monte Carlo method #28;lms [1] and Josephson junction arrays [2]. In the context of magnetism, where the BKT theory

gas-phase oxidation products through reaction with hydrogen peroxide. Atmos Envi- ron 38:4093�4098. 18: Products and quantum yields. J Chem Phys 96: 5878�5886. 37. Yu X-Y, Barker JR (2003) Hydrogen peroxide pattern, with the two oxygen atoms and peroxidic hydrogen atom in CH3OOH forming hydrogen bonds

Increase of electron beam cross emittance due to quantum fluctuations of synchrotron radiation in rectangular focusing elements is considered. The general expression for emittance increase and its analysis for a plane beam with size ratio x>>y in final qu...

The authors have investigated one-hole motion in the anisotropic three-dimensional (A3D) quantum antiferromagnet by use of the A3D t-J model in a simple cubic lattice. The hopping matrix element and the Heisenberg exchange energy are t and J in the xy pla...

This paper is intended to be a tutorial on multigrid Monte Carlo techniques, illustrated with two examples. Path-integral quantum Monte Carlo is seen to take only a finite amount of computer time even as the paths are discretized on infinitesimally small scales. A method for eliminating critical slowing down completely/emdash/even for models with discrete degrees of freedom, ...

The quantum Hall effect in two-dimensional electron systems has been reported in a number of heterostructures, in which the Hall resistance, rho sub xy = h ((nu)(e-sq)) shows plateaus at integral values of v and the magneto-resistance rho sub xx tends to ...

for time-dependent quantum mechanical system Hyeong-Chan Kim 1 and Jae Hyung Yee 2 Institute of Physics and the boundary conditions at x = 0; #6;1 uniquely determine f(x). [9] Hyeong-Chan Kim and Jae Hyung Yee, \\Zero mode the inverse function x(y) be de#12;ned uniquely. We use y as a basic variable instead of x, because its range

Superfluidity in the Bose-Hubbard model is destroyed by the interplay of thermal and quantum phase fluctuations. In two dimensions, Berezinskii-Kosterlitz-Thouless theory predicts that deep in the superfluid phase quasi-long-range order is destroyed by the proliferation of thermally induced free vortices. As the Mott insulator regime is approached, the effect of ...

We investigate whether a two-qubit quantum gate can be implemented in a scattering process involving a flying and a static qubit. We focus on a paradigmatic setup made out of a mobile particle and a quantum impurity, whose respective spin degrees of freedom couple to each other during a one-dimensional scattering process. A condition for the occurrence of ...

We investigate whether a two-qubit quantum gate can be implemented in a scattering process involving a flying and a static qubit. To this end, we focus on a paradigmatic setup made out of a mobile particle and a quantum impurity, whose respective spin degrees of freedom couple to each other during a one-dimensional scattering process. Once a condition for ...

In an n-InxGa1-xAs/GaAs double quantum well (x~0.2) the temperature dependence of the longitudinal resistance ?xx(T) of a 2D electron gas with low mobility and with an electron density close to the B=0 metal-insulator transition is of an ``insulator'' character in the temperature interval T=1.8-70 K(kBT?/?=0.1-3.8). Anomalous temperature dependence of ...

We propose a decoupling-free nuclear-spin quantum computer installed on a quantum electron spin chain with a singlet ground state and a finite spin gap. Qubits are I=1/2 nuclear spins implanted periodically along the quantum spin chain. A magnetic field gradient is applied parallel to the ...

We study the Kondo Lattice and Hubbard models on a triangular lattice for band filling factor 3/4. We show that a simple non-coplanar chiral spin ordering (scalar spin chirality) is naturally realized in both models due to perfect nesting of the fermi surface. The resulting triple-Q magnetic ordering is a natural counterpart of the collinear Neel ordering of the half-filled square lattice Hubbard ...

Optical Hall conductivity ?{xy}(?) is measured from the Faraday rotation for a GaAs/AlGaAs heterojunction quantum Hall system in the terahertz-frequency regime. The Faraday rotation angle (? fine-structure constant ??mrad) is found to significantly deviate from the Drude-like behavior to exhibit a plateaulike structure around the Landau-level filling ?=2. ...

We propose experimental schemes to implement ancilla-free 1{yields}3 optimal phase covariant quantum cloning machines for x-y and x-z equatorial qubits by interfering a polarized photon, which we wish to clone, with different light resources at a six-port symmetric beam splitter. The scheme requires linear optical elements and three-photon coincidence ...

We study the properties of classical and quantum strongly nonlinear chains by means of extensive numerical simulations. Due to strong nonlinearity, the classical dynamics of such chains remains chaotic at arbitrarily low energies. We show that the collective excitations of classical chains are described by sound ...

We present a new approach to deal with the one-dimensional (1D) Heisenberg spin chain with spin S = 1. In this approach, by means of the discretized path-integral representation (DPIR), the one-dimensional quantum spin Heisenberg chain is transformed into a classical spin system. Then we use the double-chain ...

Quantum Dot-Organic Oligomer Nanostructures: Electronic Excitation Migration and Optical Memory oligomers by manipulating the structural conformations of the organic component or the size of the inorganic resonant coupling between discrete intra-chain and inter-chain excitations of the oligomer and quantum dot

A simple linear chain model, as an alternative to the orthodox Schroedinger approach, is proposed to explain the origin of the uncertainty broadening and to improve our physical insight into the difference between classical and quantum worlds. Quantum interference in space is manifested as a result of fast exchange between adjacent ...

The method of Discretized Path Integral Representation (DPIR) is used to convert the one-dimensional quantum Z3 Potts chain into a two-dimensional classical Interaction-Round a Face (IRF) model. Then we use the Double-Chain approximation to obtain the free energy and thermodynamic properties of the model.

To study local mode XY3 molecules, we use properties of the group chain U(4)?U(3)?K(3)?S(3)?C3v. For the Hamiltonian, we deduce diagonal terms and coupling terms between bonds. We analyze the stretching modes of the arsine molecule. An algebraic transition operator is built and applied to the same molecular system.

A possible three-parameter Gram-Charlier form of the Gaussian diffusivity representation of the magnetic spin spectral function is evaluated for a restricted XY Heisenberg model, a linear chain of S = 1/2 spins with only transverse exchange at elevated te...

We consider a process of parameter estimation in a spin-j system surrounded by a quantum-critical spin chain. Quantum Fisher information lies at the heart of the estimation task. We employ Ising spin chain in a transverse field as the environment which exhibits a quantum phase transition. ...

The exponential speedup of quantum walks on certain graphs, relative to classical particles diffusing on the same graph, is a striking observation. It has suggested the possibility of new fast quantum algorithms. We point out here that quantum mechanics can also lead, through the phenomenon of localization, to exponential suppression ...

In this paper we present a quantization of cellular automata. Our formalism is based on a lattice of qudits and an update rule consisting of local unitary operators that commute with their own lattice translations. One purpose of this model is to act as a theoretical model of quantum computation, similar to the quantum circuit model. It is also shown to be ...

We present an algorithm that exploits quantum parallelism to simulate randomness in a quantum system. In our scheme, all possible realizations of the random parameters are encoded quantum mechanically in a superposition state of an auxiliary system. We show how our algorithm allows for the efficient simulation of dynamics of ...

We study the critical behavior of excited states and its relation to order and chaos in the Jaynes-Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excited-state quantum phase transitions demarcating the upper edge of the superradiant phase. For the Dicke model, the signatures of criticality in ...

Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ?(xy) is nonlinear at low magnetic fields. ?(xy) is ...

Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ?xy is nonlinear at low magnetic fields. ?xy is ...

Dynamical scaling analysis is theoretically performed for the ac (optical) Hall conductivity ?xy(?F,?) as a function of Fermi energy ?F and frequency ? for the two-dimensional electron gas and for graphene. In both systems, results based on exact diagonalization show that ?xy(?F,?) displays a well-defined dynamical scaling, for which the dynamical ...

The DRAMA sequence has been considered as the milestone in the development of homonuclear dipolar recoupling. Although it has a high efficiency for double-quantum excitation in spin 1/2 systems, it is seldom used today for real applications because of its susceptibility to the deteriorating effects of chemical shift anisotropy and resonance offsets. We show in this work that ...

We study the transmission of both classical and quantum information through all the phases of a finite XXZ spin chain. This characterizes the merit of the different phases in terms of their ability to act as a quantum wire. As far as quantum information is concerned, we need only consider the transmission of ...

For the example of the generalized Toda chain in two-dimensional space it is shown that in the quantum domain the semisimple algebras of the classical problem go over into the associative Hopf algebras described by Drinfel'd as quantum algebras. In terms of the quantum algebras, the Heisenberg operators of ...