Quantum Information processing by NMR: Preparation of pseudopure states and implementation of unitary operations in a single-qutrit system

Theoretical Quantum Information Processing (QIP) has matured from the use of qubits to the use of qudits (systems having states> 2). Where as most of the experimental implementations have been performed using qubits, little experimental work has been carried out using qudits as yet. In this paper we demonstrate experimental realization of a qutrit system by nuclear magnetic resonance (NMR), utilizing deuterium (spin-1) nuclei partially oriented in liquid crystalline phase. Preparation of pseudopure states and implementation of unitary operations are demonstrated in this single-qutrit system, using transition selective pulses.Comment: 11 pages, 2 figure

Efficient Quantum State Tomography for Quantum Information Processing using a two-dimensional Fourier Transform Technique

A new method of quantum state tomography for quantum information processing is described. The method based on two-dimensional Fourier transform technique involves detection of all the off-diagonal elements of the density matrix in a two-dimensional experiment. All the diagonal elements are detected in another one-dimensional experiment. The method is efficient and applicable to a wide range of spin systems. The proposed method is explained using a 2 qubit system and demonstrated by tomographing arbitrary complex density matrices of 2 and 4 qubit systems using simulations.Comment: 11 pages and 2 figure

Neutral ZZ boson pair production due to radion resonance in the Randall-Sundrum model: prospects at the CERN LHC

The Neutral $Z$ boson pair production due to radion resonance at the Large Hadron Collider (LHC) is an interesting process to explore the notion of warped geometry (Randall-Sundrum model). Because of the enhanced coupling of radion with a pair of gluons due to trace enomaly and top(quark) loop, the radion can provide larger event rate possibility as compared to any New Physics effect. Using the proper radion-top-antitop (with the quarks being off-shell) coupling, we obtain the correct radion production rate at LHC and explore several features of a heavier radion decaying into a pair of real $Z$ bosons which subsequently decays into charged $4 l (l=e, \mu)$ leptons (the gold-plated mode). Using the signal and background event rate, we obtain bounds on radion mass $m_\phi$ and radion vev \vphi at the $5\sigma$, $10\sigma$ discovery level.Comment: 17 pages, 4 figures, minor changes in the text, result unchanged. Version to appear in Phys. Rev.

New signals for vector-like down-type quark in U(1)U(1) of E6E_6

We consider the pair production of vector-like down-type quarks in an $E_6$ motivated model, where each of the produced down-type vector-like quark decays into an ordinary Standard Model light quark and a singlet scalar. Both the vector-like quark and singlet scalar appear naturally in the $E_6$ model with masses at the TeV scale with a favorable choice of symmetry breaking pattern. We focus on the non-standard decay of the vector-like quark and the new scalar which decays to two photons or two gluons. We analyze the signal for the vector-like quark production in the $2\gamma+\geq2j$ channel and show how the scalar and vector-like quark masses can be determined at the Large Hadron Collider.Comment: 25 pages, 11 figures, 6 tables. arXiv admin note: text overlap with arXiv:1607.0081

How Do Glassy Domains Grow?

We construct the equations for the growth kinetics of a structural glass within mode-coupling theory, through a non-stationary variant of the 3-density correlator defined in Phys. Rev. Lett. 97}, 195701 (2006). We solve a schematic form of the resulting equations to obtain the coarsening of the 3-point correlator $\chi_3(t,t_w)$ as a function of waiting time $t_w$. For a quench into the glass, we find that $\chi_3$ attains a peak value $\sim t_w^{0.5}$ at $t -t_w \sim t_w^{0.8}$, providing a theoretical basis for the numerical observations of Parisi [J. Phys. Chem. B 103, 4128 (1999)] and Kob and Barrat [Phys. Rev. Lett. 78, 4581 (1997)]. The aging is not "simple": the $t_w$ dependence cannot be attributed to an evolving effective temperature.Comment: 6 pages, 5 figure