Noncommutative tori and universal sets of non-binary quantum gates

A problem of universality in simulation of evolution of quantum system and in theory of quantum computations is related with the possibility of expression or approximation of arbitrary unitary transformation by composition of specific unitary transformations (quantum gates) from given set. In an earlier paper (quant-ph/0010071) application of Clifford algebras to constructions of universal sets of binary quantum gates $U_k \in U(2^n)$ was shown. For application of a similar approach to non-binary quantum gates $U_k \in U(l^n)$ in present work is used rational noncommutative torus ${\Bbb T}^{2n}_{1/l}$. A set of universal non-binary two-gates is presented here as one example.Comment: 5 pages, REVTeX3.1, v2: spelling and misprints, 4 new ref

Formation of zebra pattern in low-frequency Jovian radio emission

We investigate the formation of zebra-like fine spectral structures (consisting of several parallel bands in the dynamic spectrum) in the Jovian broadband kilometric radiation; such radio bursts were observed by Cassini in 2000/2001. We assume that the emission is generated due to a plasma mechanism in the Io plasma torus. We have shown that the double plasma resonance effect (that was proposed earlier as a formation mechanism of the solar zebra patterns) is able to produce the observed spectral structures. The observed frequency drifts are caused, most likely, by the dynamics of the electron acceleration site. The required conditions in the emission source are discussed.Comment: Accepted for publication in Planetary & Space Scienc

Russian fiscal policy during the financial crisis

This study examines the expanding role of fiscal policy at a time of financial crisis. It analyses the stimulative fiscal measures of the Russian government in 2008-2010 and compares these with simi-lar actions taken in other countries. The risks and limitations associated with the development and implementation of the measures are analyzed. The macroeconomic effects of the fiscal policy measures are estimated using a structural vector autoregressive (SVAR) model, the fiscal multip-liers are calculated, and factors influencing multiplier size are examined.fiscal stimulus; fiscal sustainability; SVAR; fiscal multiplier; financial crisis; Russia