Quantum noise reduction using a cavity with a Bose Einstein condensate

We study an optomechanical system in which the collective density excitations (Bogoliubov modes) of a Bose Einstein condensate (BEC) is coupled to a cavity field. We show that the optical force changes the frequency and the damping constant of the collective density excitations of the BEC. We further analyze the occurrence of normal mode splitting (NMS) due to mixing of the fluctuations of the cavity field and the fluctuations of the condensate with finite atomic two-body interaction. The NMS is found to vanish for small values of the two-body interaction. We further show that the density excitations of the condensate can be used to squeeze the output quantum fluctuations of the light beam. This system may serve as an optomechanical control of quantum fluctuations using a Bose Einstein condensate.Comment: 8 figure

Deciphering Universal Extra Dimension from the top quark signals at the CERN LHC

Models based on Universal Extra Dimensions predict Kaluza-Klein (KK) excitations of all Standard Model (SM) particles. We examine the pair production of KK excitations of top- and bottom-quarks at the Large Hadron Collider. Once produced, the KK top/bottom quarks can decay to $b$-quarks, leptons and the lightest KK-particle, $\gamma_1$, resulting in 2 $b$-jets, two opposite sign leptons and missing transverse momentum, thereby mimicing top-pair production. We show that, with a proper choice of kinematic cuts, an integrated luminosity of 100 fb$^{-1}$ would allow a discovery for an inverse radius upto $R^{-1} = 750$ GeV.Comment: 18 pages, 14 figures, Accepted for publication in JHE

Entangling two Bose Einstein condensates in a double cavity system

We propose a scheme to transfer the quantum state of light fields to the collective density excitations of a Bose Einstein condensate (BEC) in a cavity. This scheme allows to entangle two BECs in a double cavity setup by transferring the quantum entanglement of two light fields produced from a nondegenerate parametric amplifier (NOPA) to the collective density excitations of the two BECs. An EPR state of the collective density excitations can be created by a judicious choice of the system parameters.Comment: 3 figure

Stability of small amplitude normal modes of a Bose-Einstein condensate with a singly quantized vortex confined in an optical lattice

We study the dynamics of a BEC with a singly quantized vortex, placed in the combined potential of a 1-D (2-D) optical lattice and an axi-symmetric harmonic trap. A time-dependent variational Lagrangian analysis shows that an optical lattice helps to stabilize the vortex which in absence of the optical lattice is unstable. We find that the normal modes are stable only if the depth of the optical potential is more than a certain critical value. This critical value of the optical potential depends on the interaction parameter.In general higher the interaction parameter,lower the value of the optical potential required to stabilize the vortex. The BEC with the singly quantized vortex is found to be relatively more unstable in a 2-D optical lattice compared to a 1-D optical lattice.Comment: Revised version with 11 pages including 1 figur

Effect of post harvest ripening on bioactive secondary metabolites and antioxidant activity in mango cv. Amrapali

Mango possesses many bioactive phytonutrients at ripe stage which boost our immune systemagainst many diseases. Post harvest ripening plays a major role in changes in those bioactivephytochemicals and their antioxidant activity. Hence, the present study was undertaken toassess the changes in bioactive phytonutrients and total antioxidant activity during ripeningof mango cv. Amrapali. The fruits were analyzed for total antioxidants, total phenols, totalflavonoids and total carotenoids from the day of harvest to its deterioration. Fruit peel andpulp color was measured with SPH850 spectrophotometer on the basis of the CIE LAB colorsystem (L*, a* and b*). The results revealed that total phenols (36.11 to 66.53mg GAE 100g-1),total flavonoids (14.33 to 34.67mg QE 100g-1), total carotenoids (2.23 to 11.47mg 100g-1) andtotal antioxidant (0.37 to 0.76 mmol Trolox 100g-1) activity increased gradually from day one toninth day after harvest and decreased slightly thereafter up to eleventh day of harvest excepttotal carotenoids, which remained constant. Strong correlations between total phenols (0.94),total flavonoids (0.86) and total carotenoids (0.97) with total antioxidant activity were noticed.Positive relationship between total carotenoids and L*, a*, b* values in mango peel and pulpduring ripening was also observed. It can be concluded that ripening affected the compositionof bioactive phytonutrients and their antioxidant activity in mango andmaximum nutraceuticalscontents were noticed from seven to nine days after harvest

Probing superfluidity of periodically trapped ultracold atoms in a cavity by transmission spectroscopy

We study a system of periodic Bose condensed atoms coupled to cavity photons using the input-output formalism. We show that the cavity will either act as a through pass Lorentzian filter when the superfluid fraction of the condensate is minimum or completely reflect the input field when the superfluid fraction is maximum. We show that by monitoring the ratio between the transmitted field and the reflected field, one can estimate the superfluid fraction.Comment: 3 page