5,945 research outputs found
Ground state energy and mass gap of a generalised quantum spin ladder
We show that a 2-leg ladder hamiltonian introduced recently by Albeverio and
Fei (cond-mat/9807341) can be made to satisfy the Hecke algebra. As a result we
have found an equivalent representation of the eigenspectrum in terms of the
spin-1/2 antiferromagnetic XXZ chain at . The values of
thermodynamic quantities such as the ground state energy and mass gap follow
from the known XXZ results.Comment: 8 pages, Late
Exactly solvable quantum spin tubes and ladders
We find families of integrable n-leg spin-1/2 ladders and tubes with general
isotropic exchange interactions between spins. These models are equivalent to
su(N) spin chains with N=2^n. Arbitrary rung interactions in the spin tubes and
ladders induce chemical potentials in the equivalent spin chains. The
potentials are n-dependent and differ for the tube and ladder models. The
models are solvable by means of nested Bethe Ansatz.Comment: 6 pages, Latex, 1 eps fig, to appear in J. Phys.
Excitations in the dilute A_L lattice model: E_6, E_7 and E_8 mass spectra
On the basis of features observed in the exact perturbation approach solution
for the eigenspectrum of the dilute A_3 model, we propose expressions for
excitations in the dilute A_4 and A_6 models. Principally, we require that
these expressions satisfy the appropriate inversion relations. We demonstrate
that they give the expected E_7 and E_6 mass spectra, and universal amplitudes,
and agree with numerical expressions for the eigenvalues.Comment: 16 pages, Latex, Elsevier style file
Multi-State Logging Freeze Detection Passive RFID Tags
In this work the design and measurement of a passive UHF RFID smart tag suitable for monitoring and recording critical temperature violations in cold chain management are presented. The tag uses moving parts to detect and log different temperate states without the requirement for transceivers, memory and batteries. A simple mechanical method is proposed whereby a moving metallic plate is trapped in one of 4 possible positions by specific environmental temperatures whereby inducing a permanent state based change in the passive RFID tag response. The latched product critical temperature violations can be monitored via the read power required to turn on the tag transponder chip which differs in each state
- …