Non-destructive Orthonormal State Discrimination

We provide explicit quantum circuits for the non-destructive deterministic discrimination of Bell states in the Hilbert space $C^{d^{n}}$, where $d$ is qudit dimension. We discuss a method for generalizing this to non-destructive measurements on any set of orthogonal states distributed among $n$ parties. From the practical viewpoint, we show that such non-destructive measurements can help lower quantum communication complexity under certain conditions.Comment: 11 pages, 6 fugure

Invisibly decaying Higgs boson in the Littlest Higgs model with T-parity

We show that there are regions in the parameter space of the Littlest Higgs model with T-parity, allowed by electroweak precision data, where the Higgs boson can decay invisibly into a pair of heavy photons A_H with a substantial branching ratio. For a symmetry breaking scale f in the range 450-600 GeV, the BR(H -> A_H A_H) can be up to 95% for an intermediate mass Higgs, and from 20% down to a few percents for a Higgs boson of mass 200 GeV or above. The total decay width of the Higgs boson can thereby be enhanced by an order of magnitude compared to the Standard Model for Higgs masses around 130 GeV.Comment: 4 pages, 2 figures, Latex (stylefiles included); Talk presented by A.N. at the International Workshop on Theoretical High Energy Physics (IWTHEP 2007), Roorkee, India, 15-20 March 2007, to appear in the proceeding

Bilarge neutrino mixing in R-parity violating supersymmetry: the role of right-chiral neutrino superfields

We consider the possibility of neutrino mass generation in a supersymmetric model where lepton number can be violated by odd units. The different patterns of mixing in the quark and lepton sectors are attributed to the persence of right-chiral neutrino superfields which (a) enter into Yukawa couplings via non-renormalizable interaction with hidden sector fields, and (b) can violate lepton number by odd units. Both of these features are shown to be the result of some global quantum number which is violated when SUSY is broken in the hidden sector. It is shown how such a scenario, together with all known R-parity violating effects, can lead to neutrino masses and bilarge mixing via seesaw as well as radiative mechanisms. Some sample values of the various parameters involved, consistent with electroweak symmetry breaking constraints, are presented as illustrations.Comment: 19 pages. Minor modificaitons are made in the text. This version is to appear in Physical Review

Observation of coherent Josephson response in the non-linear ab-plane microwave impedance of YBa2Cu3O6.95YBa_{2}Cu_{3}O_{6.95} single crystals

We report novel non-linear phenomena in the $ab$-plane microwave impedance of $YBaCu_{2}O_{7-\delta }$ single crystals. The $R_s$ vs. $H_{rf}$ data are well described by the non-linear RSJ model : $\dot{\phi}+\sin \phi =i_{rf}\cos \omega t$. The entire crystal behaves like a single Josephson junction. The extraordinary coherence of the data suggests an intrinsic mechanism.Comment: 2 pages,1 figure, Submitted to Proc. of M^2SHTSC-V (Beijing), also available at http://sagar.physics.neu.edu/preprint

High fidelity single-shot readout of a transmon qubit using a SLUG {\mu}wave amplifier

We report high-fidelity, quantum nondemolition, single-shot readout of a superconducting transmon qubit using a DC-biased superconducting low-inductance undulatory galvanometer(SLUG) amplifier. The SLUG improves the system signal-to-noise ratio by 7 dB in a 20 MHz window compared with a bare HEMT amplifier. An optimal cavity drive pulse is chosen using a genetic search algorithm, leading to a maximum combined readout and preparation fidelity of 91.9% with a measurement time of Tmeas = 200ns. Using post-selection to remove preparation errors caused by heating, we realize a combined preparation and readout fidelity of 94.3%.Comment: 4 pages and 3 figure