2,462 research outputs found
Dynamic transition in Landau-Zener-St\"uckelberg interferometry of dissipative systems: the case of the flux qubit
We study Landau-Zener-Stuckelberg (LZS) interferometry in multilevel systems
coupled to an Ohmic quantum bath. We consider the case of superconducting flux
qubits driven by a dc+ac magnetic fields, but our results can apply to other
similar systems. We find a dynamic transition manifested by a symmetry change
in the structure of the LZS interference pattern, plotted as a function of ac
amplitude and dc detuning. The dynamic transition is from a LZS pattern with
nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances
at long times (above the relaxation time). We also show that the presence of a
resonant mode in the quantum bath can impede the dynamic transition when the
resonant frequency is of the order of the qubit gap. Our results are obtained
by a numerical calculation of the finite time and the asymptotic stationary
population of the qubit states, using the Floquet-Markov approach to solve a
realistic model of the flux qubit considering up to 10 energy levels.Comment: One new figure added. Final version to be published in PR
Finite Temperature QCD Sum Rules: a Review
The method of QCD sum rules at finite temperature is reviewed, with emphasis
on recent results. These include predictions for the survival of charmonium and
bottonium states, at and beyond the critical temperature for de-confinement, as
later confirmed by lattice QCD simulations. Also included are determinations in
the light-quark vector and axial-vector channels, allowing to analyse the
Weinberg sum rules, and predict the dimuon spectrum in heavy ion collisions in
the region of the rho-meson. Also in this sector, the determination of the
temperature behaviour of the up-down quark mass, together with the pion decay
constant, will be described. Finally, an extension of the QCD sum rule method
to incorporate finite baryon chemical potential is reviewed.Comment: Minor typos corrected. To be published in the review section of
Advances in High Energy Physic
Unifying approach for fluctuation theorems from joint probability distributions
Any decomposition of the total trajectory entropy production for Markovian
systems has a joint probability distribution satisfying a generalized detailed
fluctuation theorem, when all the contributing terms are odd with respect to
time reversal. The expression of the result does not bring into play dual
probability distributions, hence easing potential applications. We show that
several fluctuation theorems for perturbed non-equilibrium steady states are
unified and arise as particular cases of this general result. In particular, we
show that the joint probability distribution of the system and reservoir
trajectory entropies satisfy a detailed fluctuation theorem valid for all times
although each contribution does not do it separately
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