104 research outputs found
Spin Squeezing via One-Axis Twisting with Coherent Light
We propose a new method of spin squeezing of atomic spin, based on the
interactions between atoms and off-resonant light which are known as
paramagnetic Faraday rotation and fictitious magnetic field of light. Since the
projection process, squeezed light, or special interactions among the atoms are
not required in this method, it can be widely applied to many systems. The
attainable range of the squeezing parameter is S^{-2/5}, where S is the total
spin, which is limited by additional fluctuations imposed by coherent light and
the spherical nature of the spin distribution.Comment: 4 pages,6 figure
Exactly solvable approximating models for Rabi Hamiltonian dynamics
The interaction between an atom and a one mode external driving field is an
ubiquitous problem in many branches of physics and is often modeled using the
Rabi Hamiltonian. In this paper we present a series of analytically solvable
Hamiltonians that approximate the Rabi Hamiltonian and compare our results to
the Jaynes-Cummings model which neglects the so-called counter-rotating term in
the Rabi Hamiltonian. Through a unitary transformation that diagonlizes the
Jaynes-Cummings model, we transform the counter-rotating term into separate
terms representing several different physical processes. By keeping only
certain terms, we can achieve an excellent approximation to the exact dynamics
within specified parameter ranges
Incoherently pumped continuous wave optical parametric oscillator broadened by non-collinear phasematching
In this paper, we report on a singly resonant optical parametric oscillator
(OPO) pumped by an amplified spontaneous emission (ASE) source. The pump
focusing conditions allow non-collinear phasematching, which resulted in a 230
nm (190 cm) spectral bandwidth. Calculations indicate that such
phasematching schemes may be used to further broaden OPO spectral bandwidths.Comment: 7 pages 4 figure
Experimental observation of three-color optical quantum correlations
Quantum correlations between bright pump, signal, and idler beams produced by
an optical parametric oscillator, all with different frequencies, are
experimentally demonstrated. We show that the degree of entanglement between
signal and idler fields is improved by using information of pump fluctuations.
This is the first observation of three-color optical quantum correlations.Comment: 3 pages, 3 figure
Noise spectroscopy of optical microcavity
The intensity noise spectrum of the light passed through an optical
microcavity is calculated with allowance for thermal fluctuations of its
thickness. The spectrum thus obtained reveals a peak at the frequency of
acoustic mode localized inside the microcavity and depends on the size of the
illuminated area. The estimates of the noise magnitude show that it can be
detected using the up-to-date noise spectroscopy technique.Comment: 10 pages, 1 figur
Narrow resonances with excitation of finite bandwidth field
The effect of the laser linewidth on the resonance fluorescence spectrum of a
two-level atom is revisited. The novel spectral features, such as hole-burning
and dispersive profiles at line centre of the fluorescence spectrum are
predicted when the laser linewidth is much greater than its intensity. The
unique features result from quantum interference between different
dressed-state transition channels.Comment: 4 pages & 4 figures, Phys. Lett. A, (in press
Laser-noise-induced correlations and anti-correlations in Electromagnetically Induced Transparency
High degrees of intensity correlation between two independent lasers were
observed after propagation through a rubidium vapor cell in which they generate
Electromagnetically Induced Transparency (EIT). As the optical field
intensities are increased, the correlation changes sign (becoming
anti-correlation). The experiment was performed in a room temperature rubidium
cell, using two diode lasers tuned to the Rb line (nm). The cross-correlation spectral function for the pump and probe fields
is numerically obtained by modeling the temporal dynamics of both field phases
as diffusing processes. We explored the dependence of the atomic response on
the atom-field Rabi frequencies, optical detuning and Doppler width. The
results show that resonant phase-noise to amplitude-noise conversion is at the
origin of the observed signal and the change in sign for the correlation
coefficient can be explained as a consequence of the competition between EIT
and Raman resonance processes.Comment: Accepted for publication in EPJ
Paramagnetic Faraday rotation with spin-polarized ytterbium atoms
We report observation of the paramagnetic Faraday rotation of spin-polarized
ytterbium (Yb) atoms. As the atomic samples, we used an atomic beam, released
atoms from a magneto-optical trap (MOT), and trapped atoms in a
far-off-resonant trap (FORT). Since Yb is diamagnetic and includes a spin-1/2
isotope, it is an ideal sample for the spin physics, such as quantum
non-demolition measurement of spin (spin QND), for example. From the results of
the rotation angle, we confirmed that the atoms were almost perfectly
polarized.Comment: 8 pages, 20 figure
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