共查询到20条相似文献,搜索用时 31 毫秒
1.
Sanjukta Roy Saptarishi Chaudhuri C. S. Unnikrishnan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):231-237
We discuss the expansion dynamics under mean-field repulsion of an array of 87Rb Bose-Einstein condensates produced in an all-optical scheme involving 1D lattice with nearly 105 atoms, after fast evaporative cooling of just about 1 s. Single site occupation exceeds 2 × 104 in our experiments. The possibility of transition to two-dimensionality was also investigated. The expansion behavior of
the high density multiple micro-condensates produced directly in the CO2 laser 1D optical lattice, with a lattice spacing of 5.3 μm, agrees well with a numerical simulation based on the mean-field
theory. 相似文献
2.
Pasi Huovinen Péter Petreczky Christian Schmidt 《Central European Journal of Physics》2012,10(6):1385-1387
We employ the lattice QCD data on Taylor expansion coefficients to extend our previous parametrization of the equation of state to finite baryon density. When we take into account lattice spacing and quark mass dependence of the hadron masses, the Taylor coefficients at low temperature are equal to those of hadron resonance gas. Parametrized lattice equation of state can thus be smoothly connected to the hadron resonance gas equation of state at low temperatures. 相似文献
3.
de Los Santos F Munoz MA 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):1161-1163
We use field theoretic renormalization group methods to study the critical behavior of a recently proposed Langevin equation for driven lattice gases under infinitely fast drive. We perform an expansion around the upper critical dimension, d(c)=4, and obtain the critical exponents to one-loop order. The main features of the two-loop calculation are also outlined. The renormalized theory is shown to exhibit a behavior different from the standard field theory for the driven lattice gas with finite driving, i.e., it is not mean-field-like. 相似文献
4.
5.
B. Borasoy E. Epelbaum H. Krebs D. Lee U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):357-367
We discuss lattice simulations of the ground state of dilute neutron matter at next-to-leading order in chiral effective field
theory. In a previous paper the coefficients of the next-to-leading-order lattice action were determined by matching nucleon-nucleon
scattering data for momenta up to the pion mass. Here the same lattice action is used to simulate the ground state of up to
12 neutrons in a periodic cube using Monte Carlo simulations. We explore the density range from 2% to 8% of normal nuclear
density and analyze the ground-state energy as an expansion about the unitarity limit with corrections due to finite scattering
length, effective range, and P -wave interactions. 相似文献
6.
We present phase diagrams for a polarized Fermi gas in an optical lattice as a function of temperature, polarization, and lattice filling factor. We consider the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO), Sarma or breached pair, and BCS phases, and the normal state and phase separation. We show that the FFLO phase appears in a considerable portion of the phase diagram. The diagrams have two critical points of different nature. We show how various phases leave clear signatures to momentum distributions of the atoms which can be observed after time of flight expansion. 相似文献
7.
We investigate the phenomena of symmetry breaking and phase transition
in the ground state of Bose-Einstein condensates (BECs) trapped in
a double square well and in an optical lattice well, respectively.
By using standing-wave expansion method, we present symmetric and
asymmetric ground state solutions of nonlinear Schrödinger
equation (NLSE) with a symmetric double square well potential for
attractive nonlinearity. In particular, we study the ground state
wave function's properties by changing the depth of potential
and atomic interactions (here we restrict ourselves to the attractive
regime). By using the Fourier grid Hamiltonian method, we also
reveal a phase transition of BECs trapped in one-dimensional
optical lattice potential. 相似文献
8.
9.
The linked cluster series expansion proposed by Nickel is extended to the ground state and axial string tension of lattice gauge theory. Proofs of these expansions and applications to Z2 and U(1) gauge theory in 2 + 1 dimensions are presented. We also propose a new finite cluster scaling method based on the linked-cluster expansion and test it against known results for Z2 gauge theory. The utility of the method in studying more complicated lattice gauge theories is emphasized. 相似文献
10.
Loukakos PA Lisowski M Bihlmayer G Blügel S Wolf M Bovensiepen U 《Physical review letters》2007,98(9):097401
Transient changes of the complex self-energy of the 5d(z2) surface state on Gd(0001) after intense optical excitation are investigated by femtosecond time-resolved photoemission. We observe an ultrafast (<100 fs) broadening of the linewidth due to e-e scattering followed by a decrease of the binding energy due to thermal expansion of the lattice. In addition, we resolve a periodic breathing of the band structure which originates from a coherent phonon. An amplitude of 1 pm is derived from the binding energy shift upon lattice displacement calculated by density functional theory. 相似文献
11.
Fritz Haake Maciej Lewenstein Martin Wilkens 《Zeitschrift für Physik B Condensed Matter》1984,55(3):211-218
We construct the most general real space renormalization for the two-dimensional kinetic Ising model on the triangular lattice which, to second order in the high-temperature expansion, conserves detailed balance and avoids fast transients for the cell spins. We show the corresponding dynamical recursion relations (as well as the exponentz) to be unaltered with respect to the ones found, in a previous paper, for a completely different class of transformations. This finding resolves long-standing confusions and controversies. 相似文献
12.
On the possibility of electric transport mediated by long living intrinsic localized solectron modes
O.G. Cantu Ros L. Cruzeiro M. G. Velarde W. Ebeling 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,80(4):545-554
We consider a polaron Hamiltonian in which not only the lattice and the electron-lattice interactions, but also the electron
hopping term is affected by anharmonicity. We find that the one-electron ground states of this system are localized in a wide
range of the parameter space. Furthermore, low energy excited states, generated either by additional momenta in the lattice
sites or by appropriate initial electron conditions, lead to states constituted by a localized electron density and an associated
lattice distortion, which move together through the system, at subsonic or supersonic velocities. Thus we investigate here
the localized states above the ground state which correspond to moving electrons. We show that besides the stationary localized
electron states (proper polaron states) there exist moving localized solectron states which can be easily excited. The evolution
of these localized states suggests their potential as new carriers for fast electric charge transport. 相似文献
13.
《Physics letters. [Part B]》1986,166(1):78-82
We propose a resummation scheme for strong-coupling diagrams in two-dimensional lattice supersymmetric theories originally derived by Bender et al. To any given order, this reduces the number of diagrams drastically. We calculate the ground state energy density up to eighth order and obtain a modified strong-coupling series in terms of a new expansion parameter which seems to have a smoother continuum limit. 相似文献
14.
We have investigated theoretically the evolution of spin-dependent atomic wave packets in a harmonic magnetic trapping potential. For a Bose-condensed gas, which undergoes a Mott insulator transition and a spin-dependent transport, the atomic wavefunction can be described by an entangled single-atom state. Due to the confinement of the harmonic potential, the density distributions exhibit periodic decay and revival, which is different from the case of free expansion after switching off the combined harmonic and optical lattice potential. 相似文献
15.
We present an explicit analytical analysis of the ground state of vortex lattice structure, based on a minimization of the generalized Gross–Pitaevskii energy functional in a trapped rotating Fermi superfluid gas. By a Bogoliubov-like transformation we find that the coarse-grained average of the atomic density varies as inverted parabola in three dimensional cases; the Fermi superfluid in the BEC regime enters into the lowest Landau level at fast rotation, in which the vortices form an almost regular triangular lattice over a central region and the vortex lattice is expanded along the radial direction in the outer region; the fluid in the unitarity and BCS regimes occupies many low-lying Landau levels, in which a trapped gas with a triangular vortex lattice has a superfluid core surrounded by a normal gas. The calculation is qualitatively consistent with recent numerical and experimental data both in the vortex lattice structure and vortex numbers and in the density profiles versus the stirring frequency in the whole BCS–BEC crossover. 相似文献
16.
We develop a controlled high-temperature expansion for nonequilibrium steady states of the driven lattice gas, the "Ising model" for nonequilibrium physics. We represent the steady state as P(eta) alpha e(-betaH(eta)-psi(eta)) and evaluate the lowest order contribution to the nonequilibrium effective interaction psi(eta). We see that, in dimensions d > or = 2, all models with nonsingular transition rates yield the same summable psi(eta), suggesting the possibility of describing the state as a Gibbs state similar to equilibrium. The models with the Metropolis rule show exceptional behavior. 相似文献
17.
Magnetic and electronic structure calculations are carried out for hypothetical zinc-blende (zb) phase of FeX (X=P, As, Sb) by using the full-potential linearized augmented plane wave (FLAPW) method. For zb FeSb, the total energy has been calculated as a function of lattice constant in ferromagnetic (FM) and antiferromagnetic (AFM) states. We found that the ground state of zb FeSb is very stable with respect to compression and expansion of the unit cell. The magnetic moment of zb FeSb in the AFM state is increasing with the lattice constant. The magnetic and electronic structures calculations of FeAs (FeP) are carried out for the lattice constants of GaAs (GaP), InAs (InP), and Si. Our finding shows that AFM is the ground state for all of our calculated zb FeX compounds and do not belong to the class of zb half metallic ferromagnets. 相似文献
18.
We present results of first-principle calculation of the electronic structure and phase stability of the parent compound of Fe-based superconductors, FeSe, in a magnetically ordered state. In particular, we investigate ferromagnetic (FM) and two different types of antiferromagnetic (AFM) configurations (with magnetic structure vectors (π, 0) and (π, π)). Our results for the total energy exhibit a two-minimum shape for the FM and a standard parabolic-like behavior for the AFM configurations. We find a remarkable reconstruction of the electronic structure near the M point of the Brillouin zone, which is accompanied with a rapid increase in magnetic moment upon expansion of the lattice volume. On that basis we propose that both the anomalous behavior of FeSe upon expansion of the lattice reported for the paramagnetic state [Leonov et al., Phys. Rev. Lett. 115, 106402 (2015)] and that obtained in the present work have a common origin. 相似文献
19.
We study the asymptotics of solutions of the Boltzmann equation describing the kinetic limit of a lattice of classical interacting
anharmonic oscillators. We prove that, if the initial condition is a small perturbation of an equilibrium state, and vanishes
at infinity, the dynamics tends diffusively to equilibrium. The solution is the sum of a local equilibrium state, associated
to conserved quantities that diffuse to zero, and fast variables that are slaved to the slow ones. This slaving implies the
Fourier law, which relates the induced currents to the gradients of the conserved quantities.
Partially supported by the Belgian IAP program P6/02.
Partially supported by the Academy of Finland. 相似文献
20.
YU XueCai HUANG Xue & YE YuTang School of Opto-Electrical Information University of Electronic Science Technology of China Chengdu China 《中国科学G辑(英文版)》2007,50(2):177-184
Critical temperature and condensate fraction of Bose-Einstein condensation in the optical lattice are studied. The results show that the critical temperature in optical lattices can be characterized with an equivalent critical temperature in a single lattice, which provide a fast evaluation of critical temperature and condensate fraction of Bose-Einstein condensation confined with pure optical trap. Critical temperature can be estimated with an equivalent critical temperature. It is predicted that critical temperature is proportional to q in q number lattices for superfluid state and should be equal to that in a single lattic for Mott insulate state. Required potential depth or Rabi frequency and maximum atom number in the lattices both for superfluid state and Mott state are presented based on views of thermal mechanical statistics. 相似文献