56 research outputs found
Quantum correlations and fluctuations in the pulsed light produced by a synchronously pumped optical parametric oscillator below its oscillation threshold
We present a simple quantum theory for the pulsed light generated by a
synchronously pumped optical parametric oscillator (SPOPO) in the degenerate
case where the signal and idler trains of pulses coincide, below threshold and
neglecting all dispersion effects. Our main goal is to precise in the obtained
quantum effects, which ones are identical to the c.w. case and which ones are
specific to the SPOPO. We demonstrate in particular that the temporal
correlations have interesting peculiarities: the quantum fluctuations at
different times within the same pulse turn out to be totally not correlated,
whereas they are correlated between nearby pulses at times that are placed in
the same position relative to the centre of the pulses. The number of
significantly correlated pulses is of the order of cavity finesse. We show also
that there is perfect squeezing at noise frequencies multiple of the pulse
repetition frequency when one approaches the threshold from below on the signal
field quadrature measured by a balanced homodyne detection with a local
oscillator of very short duration compared to the SPOPO pulse length.Comment: 12 pages, 3 figure
Experimental Vacuum Squeezing in Rubidium Vapor via Self-Rotation
We report the generation of optical squeezed vacuum states by means of
polarization self-rotation in rubidium vapor following a proposal by Matsko et
al. [Phys. Rev. A 66, 043815 (2002)]. The experimental setup, involving in
essence just a diode laser and a heated rubidium gas cell, is simple and easily
scalable. A squeezing of 0.85+-0.05 dB was achieved
Dynamic nuclear polarization and spin-diffusion in non-conducting solids
There has been much renewed interest in dynamic nuclear polarization (DNP),
particularly in the context of solid state biomolecular NMR and more recently
dissolution DNP techniques for liquids. This paper reviews the role of spin
diffusion in polarizing nuclear spins and discusses the role of the spin
diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in
a special issue that is being published in connection with the DNP Symposium
help in Nottingham in August 200
Experimental characterization of continuous-variable entanglement
We present an experimental analysis of quadrature entanglement produced from a pair of amplitude squeezed beams. The correlation matrix of the state is characterized within a set of reasonable assumptions, and the strength of the entanglement is gauged using measures of the degree of inseparability and the degree of Einstein-Podolsky-Rosen (EPR) paradox. We introduce controlled decoherence in the form of optical loss to the entangled state, and demonstrate qualitative differences in the response of the degrees of inseparability and EPR paradox to this loss. The entanglement is represented on a photon number diagram that provides an intuitive and physically relevant description of the state. We calculate efficacy contours for several quantum information protocols on this diagram, and use them to predict the effectiveness of our entanglement in those protocols
Recommended from our members
COHERENT ENERGY MIGRATION IN SOLIDS: DETERMINATION OF AVERAGE COHERENCE LENGTH IN ONE-DIMENSIONAL SYSTEMS USING TUNABLE DYE LASERS
Recommended from our members
THE ORIGIN OF VIBRATIONAL DEPHASING OF POLYATOMIC MOLECULES IN CONDENSED PHASES
THE EFFECT OF ELECTRIC AND MAGNETIC FIELDS ON THE 7F0↔5D0 TRANSITION OF BaClF : Sm2+ USING PHOTON-GATED HOLEBURNING
A new mechanism of spectral holeburning by 2-step photoionization ("photon-gated" holeburning) has recently been demonstrated. In BaClF : Sm2+, this leads to permanent spectral holes 25 MHz wide which we have used to measure small linear Stark and nonlinear Zeeman coefficients of the 7F0↔5D0 transition of Sm2+. The Zeeman coefficients agree within 4% with those calculated assuming free ion 4f6 wave functions for 7F0 and 5D0
PHOTON GATED HOLEBURNING BY 2-STEP PHOTOIONIZATION
We report the observation of photon-gated spectral holeburning in which persistent holes are burned in an inhomogeneoulsy broadened absorption line only in the presence of a second gating light source. The measurements were made in BaClF : Sm2+ and involve 2-step photoionization of Sm2+. A remarkable and novel feature of this System is that holes can be recovered after temperature cycling to 300 K for several days
- …