93,319 research outputs found
Quantum state transfer between field and atoms in Electromagnetically Induced Transparency
We show that a quasi-perfect quantum state transfer between an atomic
ensemble and fields in an optical cavity can be achieved in Electromagnetically
Induced Transparency (EIT). A squeezed vacuum field state can be mapped onto
the long-lived atomic spin associated to the ground state sublevels of the
Lambda-type atoms considered. The EIT on-resonance situation show interesting
similarities with the Raman off-resonant configuration. We then show how to
transfer the atomic squeezing back to the field exiting the cavity, thus
realizing a quantum memory-type operation.Comment: 8 pages, 4 figure
Parametric Self-Oscillation via Resonantly Enhanced Multiwave Mixing
We demonstrate an efficient nonlinear process in which Stokes and anti-Stokes
components are generated spontaneously in a Raman-like, near resonant media
driven by low power counter-propagating fields. Oscillation of this kind does
not require optical cavity and can be viewed as a spontaneous formation of
atomic coherence grating
Dark-State Polaritons in Electromagnetically Induced Transparency
We identify form-stable coupled excitations of light and matter (``dark-state
polaritons'') associated with the propagation of quantum fields in
Electromagnetically Induced Transparency. The properties of the dark-state
polaritons such as the group velocity are determined by the mixing angle
between light and matter components and can be controlled by an external
coherent field as the pulse propagates. In particular, light pulses can be
decelerated and ``trapped'' in which case their shape and quantum state are
mapped onto metastable collective states of matter. Possible applications of
this reversible coherent-control technique are discussed.Comment: 4 pages, 2 figure
Interacting Dark Resonances: Interference Effects Induced by Coherently Altered Quantum Superpositions
We predict the possibility of sharp, high-contrast resonances in the optical
response of a broad class of systems, wherein interference effects are
generated by coherent perturbation or interaction of dark states. The
properties of these resonances can be manipulated to design a desired atomic
response.Comment: 4 pages, 3 figures, RevTeX, submitted to PRL; changed three numbers
in Fig. 3 (caption
Symmetric photon-photon coupling by atoms with Zeeman-split sublevels
We propose a simple scheme for highly efficient nonlinear interaction between
two weak optical fields. The scheme is based on the attainment of
electromagnetically induced transparency simultaneously for both fields via
transitions between magnetically split F=1 atomic sublevels, in the presence of
two driving fields. Thereby, equal slow group velocities and symmetric
cross-coupling of the weak fields over long distances are achieved. By simply
tuning the fields, this scheme can either yield giant cross-phase modulation or
ultrasensitive two-photon switching.Comment: Modified scheme, 4 pages, 1 figur
High efficiency photon counting using stopped light
Single-photon detection and photon counting play a central role in a large
number of quantum communication and computation protocols. While the efficiency
of state-of-the-art photo-detectors is well below the desired limits, quantum
state measurements in trapped ions can be carried out with efficiencies
approaching 100%. Here, we propose a method that can in principle achieve ideal
photon counting, by combining the techniques of photonic quantum memory and
ion-trap fluorescence detection: after mapping the quantum state of a
propagating light pulse onto metastable collective excitations of a trapped
cold atomic gas, it is possible to monitor the resonance fluorescence induced
by an additional laser field that only couples to the metastable excited state.
Even with a photon collection/detection efficiency as low as 10%, it is
possible to achieve photon counting with efficiency approaching 100%.Comment: 4 page
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