共查询到20条相似文献,搜索用时 734 毫秒
1.
The talk, based on [1], analyzes the consequences of the combined effect of the consequences of the assumption that the effects of quantum coherence and the resulting angular ordering in QCD cascades are disrupted within the finite-sized hot fireball created in ultrarelativistic heavy ion collisions and of the collisional energy losses of the cascade gluons and final hadronic clusters. 相似文献
2.
We study the one hole spectral function in a model for LaMnO3 including both the effects of orbital ordering and the quantum decoherence due to the antiferromagnetic coupling between the ferromagnetic layers. We find that the classical picture of a ferromagnetic polaron does not apply and free dispersion is replaced by rigid quasiparticles on the scale of magnetic excitations, while the spectra are dominated by the incoherent spectral weight at high energies. These results have important implications on the in-plane transport and angular resolved photoemission in the manganites. 相似文献
4.
We consider dynamically generated spin squeezing in interacting bimodal condensates. We show that particle losses and non-zero temperature effects in a multimode theory completely change the scaling of the best squeezing for large atom numbers. We present the new scalings and we give approximate analytical expressions for the squeezing in the thermodynamic limit. Besides reviewing our recent theoretical results, we give here a simple physical picture of how decoherence acts to limit the squeezing. We show in particular that under certain conditions the decoherence due to losses and non-zero temperature acts as a simple dephasing. 相似文献
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Regensburger A Bersch C Hinrichs B Onishchukov G Schreiber A Silberhorn C Peschel U 《Physical review letters》2011,107(23):233902
We study light propagation in a photonic system that shows stepwise evolution in a discretized environment. It resembles a discrete-time version of photonic waveguide arrays or quantum walks. By introducing controlled photon losses to our experimental setup, we observe unexpected effects like subexponential energy decay and formation of complex fractal patterns. This demonstrates that the interplay of linear losses, discreteness and energy gradients leads to genuinely new coherent phenomena in classical and quantum optical experiments. Moreover, the influence of decoherence is investigated. 相似文献
7.
Entropy squeezing for a two-level atom in two-mode Raman coupled model with intrinsic decoherence 总被引:1,自引:0,他引:1 下载免费PDF全文
In this paper, we investigate the entropy squeezing for a two-level
atom interacting with two quantized fields through Raman coupling.
We obtain the dynamical evolution of the total system under the
influence of intrinsic decoherence when the two quantized fields are
prepared in a two-mode squeezing vacuum state initially. The effects
of the field squeezing factor, the two-level atomic transition
frequency, the second field frequency and the intrinsic decoherence
on the entropy squeezing are discussed. Without intrinsic
decoherence, the increase of field squeezing factor can break the
entropy squeezing. The two-level atomic transition frequency changes
only the period of oscillation but not the strength of entropy
squeezing. The influence of the second field frequency is
complicated. With the intrinsic decoherence taken into
consideration, the results show that the stronger the intrinsic
decoherence is, the more quickly the entropy squeezing will
disappear. The increase of the atomic transition frequency can
hasten the disappearance of entropy squeezing. 相似文献
8.
We study the decoherence of a single electron spin in an isolated quantum dot induced by hyperfine interaction with nuclei. The decay is caused by the spatial variation of the electron wave function within the dot, leading to a nonuniform hyperfine coupling A. We evaluate the spin correlation function and find that the decay is not exponential but rather power (inverse logarithm) lawlike. For polarized nuclei we find an exact solution and show that the precession amplitude and the decay behavior can be tuned by the magnetic field. The decay time is given by (planck)N/A, where N is the number of nuclei inside the dot, and the amplitude of precession decays to a finite value. We show that there is a striking difference between the decoherence time for a single dot and the dephasing time for an ensemble of dots. 相似文献
9.
We investigate the relationship between the exact second-order cross section in QCD and the dipole cascade model as implemented in ARIADNE. We show that there is generally good agreement (very good in case one would average over different states in phase space). The relation between the probabilities to produce some states depends upon the way the recoil problems are treated in the cascade. We exhibit some observable consequences of the interference effects between different colour ordering in the states. 相似文献
10.
We study the mechanism and probability of in-medium hadronization in the deconfined medium produced in heavy-ion collisions at RHIC and LHC. We show the likelihood of color-neutral objects to be formed inside the partonic fireball and the probability of these states to escape the medium with reduced interaction strength and energy loss. We will suggest specific measurements that are sensitive to the early degrees of freedom and show predictions for these measurements at RHIC and the LHC. 相似文献
11.
We propose a simple approach for suppressing decoherence of a wave packet excited in an anharmonic oscillator. We show that when a resonant external field forces the oscillator to follow the driving force, motion around the resonant trajectory inside a stable resonant island can be made almost completely immune to the environment. As an example, we study suppression of decoherence due to coupling to thermally populated rotations in vibrational wave packets in a Na2 molecule. 相似文献
12.
We compare theoretically the effects of channel decoherence on entangled coherent states (ECSs) and entangled squeezed states (ESSs) as non-orthogonal states. The comparison is achieved in the case when the interaction with the noisy environment is symmetric and when it is asymmetric. In the first case, we notice a robustness of ECSs compared with ESSs against the photons losses. This robustness increases with a good way after using a higher amplitudes. However, in the asymmetric decoherence case, the ESSs resist more the photon losses compared with the ECSs. 相似文献
13.
LIU Xiao-Shu WU Re-Bing LIU Yang LIU Wen-Zhang LONG Gui-Lu 《理论物理通讯》2005,44(5):810-814
In this paper, we study the control problem of adiabatic decoherence in a three-level atom. We will find thedecoupling bang-bang group for various configurations, including the V configuration and the cascade type of three-level atom subjected to adiabatic decoherence. We also give the programs to design a sequence of periodic twinborn pulses to suppress the decoherence. 相似文献
14.
In this paper, we study the control problem of adiabatic decoherence in a three-level atom. We will find the decoupling bang-bang group for various configurations, including the V configuration and the cascade type of three-levelatom subjected to adiabatic decoherence. We also give the programs to design a sequence of periodic twinborn pulses to suppress the decoherence. 相似文献
15.
Ashish V. Shelke Bhuvaneshwar Gera Naresh K. Maheshwari Ram K. Singh 《Combustion Theory and Modelling》2019,23(3):387-413
Occurrences of fireball close to plant buildings due to the release of flammable hydrocarbon fuel caused by the formation of fuel vapour cloud poses severe safety concerns. On the availability of potential ignition source, the induced fireball would cause the damage to the structures of nuclear power plant by direct contact, radiation and/or convection of hot combustion products through the opening of air intakes and ducts. In the present paper, the accidental/ experimental observations and theoretical studies of fireball are summarised. Computational fluid dynamics (CFD) analyses have been carried out to study the behaviour of fireball using OpenFOAM CFD software. The parametric studies are conducted by varying the mass of fuel, inlet velocity and inlet diameter. The new correlations for fireball diameter and duration have been proposed based on the parametric studies using CFD simulations. The fireball with a larger amount of fuel releases the heat slower and for a longer duration. The high heat released rate (HRR) is observed in case of a larger inlet diameter used for the same mass. The incident radiation from the fireball is calculated at different locations to assess thermal hazard. Analysis performed show that various parameters like fireball diameter, duration and the radiative flux falling at different locations can be predicted well using CFD code. 相似文献
16.
We have made bulk and local investigations on defect induced magnetism in highly oriented pyrolytic graphite (HOPG) irradiated with a 40 MeV carbon beam. The local magnetic response of irradiated HOPG was studied by measuring the hyperfine field of recoil implanted (19)F using γ-ray time differential perturbed angular distribution (TDPAD) measurements. While the bulk magnetic properties of the irradiated sample show features characteristic of room temperature ferromagnetism, the hyperfine field data reflect enhanced paramagnetism with no indication of long range magnetic ordering. The experimental studies are further supported by ab initio density functional calculations. We believe that the ferromagnetic response in irradiated HOPG arises mostly from defect induced magnetic moments of carbon atoms in the near surface region, while those deep inside the host matrix remain paramagnetic. 相似文献
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B. Andersson P. Dahlqvist G. Gustafson 《Zeitschrift fur Physik C Particles and Fields》1989,44(3):455-460
The multiplicity measure on colour-connected partonic states introduced in [1] is further generalized and we show how to partition the properties of the final state hadronic multiplicity distributions into one part depending upon the partonic cascade and one depending upon the fragmentation inside the Lund model framework. We also show the stability of the measure with respect to variations in the energy and the possible cascade cutoffs and investigate the approximations made in the analytical formulas by means of Monte Carlo simulated events. 相似文献
19.
J. Schaffner I. N. Mishustin L. M. Satarov H. Stöcker W. Greiner 《Zeitschrift für Physik A Hadrons and Nuclei》1991,341(1):47-52
The relativistic meson field theory is used to study the effects of the in-medium interaction on the predicted antibaryon abundancy in hot hadronic matter. It is demonstrated that subtreshold production of antiprotons in high energy heavy ion collisions at Elab =1–2 GeV/nucleon is enhanced by 2–3 orders of magnitude as compared to a standard fireball model estimate. Furthermore, we show that after the inclusion of interactions the anti-hyperon yields, e.g. \(\bar \Lambda \) /π ? are enhanced by about a factor ten. Predicted yields are in excess of the data measured by the NA35 and WA85 collaborations at CERN. The annihilation of antibaryons in surrounding matter at the final stage of the reaction may essentially reduce their abundancy. 相似文献
20.
《Nuclear Physics A》1998,635(4):511-541
We numerically solve the transport equations for a quark gas described by the the Nambu-Jona-Lasinio model. The mean field equations of motion, which consist of the Vlasov equation for the density and the gap equation for the mean field, are discussed, and energy and momentum conservation are proven. Numerical solutions of the partial differential equations are obtained by applying finite difference methods. For an expanding fireball the light quark mass evolves from small values initially to the value of 350 MeV. This leads to a depletion of the high energy part of the quark spectrum and an enhancement at low momenta. When collisions are included one obtains an equation of the Boltzmann type, where the transition amplitudes depend on the properties of the medium. These equations are given for flavor SU(3), i.e. including strangeness. They are solved numerically in the relaxation time approximation and the time evolution of various observables is given. Medium effects in the relaxation times do not significantly influence the shape of the spectra. The mass of the strange quark changes little during the expansion. The strangeness yield and the slope temperatures of the final spectra are studied as a function of the size of the initial fireball. 相似文献