7,628 research outputs found
High probability state transfer in spin-1/2 chains: Analytical and numerical approaches
This article is devoted to the development of analytical and numerical
approaches to the problem of the end-to-end quantum state transfer along the
spin-1/2 chain using two methods: (a) a homogeneous spin chain with week end
bonds and equal Larmor frequencies and (b) a homogeneous spin chain with end
Larmor frequencies different from inner ones. A tridiagonal matrix
representation of the XY Hamiltonian with nearest neighbor interactions
relevant to the quantum state transfer is exactly diagonalized for a
combination of the above two methods. In order to take into account
interactions of the remote spins we used numerical simulations of the quantum
state transfer in ten-node chains. We compare the state transfer times obtained
using the two above methods for chains governed by the both XY and XXZ
Hamiltonians and using both nearest neighbor and all node interactions.Comment: 16 pages, 5 figure
An Exact Solution for the Lattice Gas Model in One Dimension
A simple method to obtain a canonical partition function for one dimensional
lattice gas model is presented. The simplification is based upon rewriting a
sum over all possible configurations to a sum over numbers of clusters in the
system.Comment: 6 pages, LaTe
The influence of motor activity on the development of cardiac arrhythmias during experimental emotional stress
Experimental emotional stress which can produce various disorders of cardiac rhythm: sinus tachycardia, atrial fibrillation, ventricular, extrasystoles and paroxysmal ventricular tachysystoles was studied. In these conditions the adrenalin content in the blood and myocardium is increased 3 to 4 times. It is found that moderate motor activity leads to a relative decrease of adrenalin in the myocardium and arrest of cardiac arrhythmias
Magnetic properties of ferrofluid emulsions: The effect of droplet elongation
The paper is concerned with a theoretical explanation of the experimentally observed effect of non-monotonic field dependence of the effective magnetic permeability of ferrofluid emulsion. In a weak magnetic field, the growth of the induced droplet magnetic moment is faster than the linear one due to the droplet elongation accompanied by the reduction of the demagnetizing field. Thus, the emulsion magnetic permeability increases in weak magnetic fields. Further strengthening of the external magnetic field cannot lead to a significant decrease of the demagnetizing field, as the droplets are already highly elongated. On the other hand, the magnetic susceptibility of the ferrofluid reduces with the field strength. Hence, the effective magnetic permeability of the ferrofluid emulsion starts decreasing. The developed theoretical model describes well the experimental observations
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