2,424 research outputs found
diffractive production in the direct photon process at HERA
We present a study of diffractive production in the direct
photon process at HERA based on the factorization theorem for lepton-induced
hard diffractive scattering and the factorization formalism of the
nonrelativistic QCD (NRQCD) for quarkonia production. Using the diffractive
gluon distribution function extracted from HERA data on diffractive deep
inelastic scattering and diffractive dijet photon production, we show that this
process can be studied at HERA with present integrated luminosity, and can give
valuable insights in the color-octet mechanism for heavy quarkonia production.Comment: Revtex, 21 pages, 7 EPS figure
Transverse Mode Revival of a Light-Compensated Quantum Memory
A long-lived quantum memory was developed based on light-compensated cold
Rb atoms in a dipole trap. The lifetime of the quantum memory was
improved by 40 folds, from 0.67 ms to 28 ms with the help of a compensation
laser beam. Oscillations of the memory efficiency due to the transverse mode
breathing of the singly-excited spin wave have been clearly observed and
clarified with a Monte-Carlo simulation procedure. With detailed analysis of
the decoherence processes of the spin wave in cold atomic ensembles, this
experiment provides a benchmark for the further development of high-quality
quantum memories.Comment: 4 pages, 4 figure
A Deterministic and Storable Single-Photon Source Based on Quantum Memory
A single photon source is realized with a cold atomic ensemble (Rb
atoms). In the experiment, single photons, which is initially stored in an
atomic quantum memory generated by Raman scattering of a laser pulse, can be
emitted deterministically at a time-delay in control. It is shown that
production rate of single photons can be enhanced by a feedback circuit
considerably while the single-photon quality is conserved. Thus our present
single-photon source is well suitable for future large-scale realization of
quantum communication and linear optical quantum computation
- …