2,239 research outputs found
Atomic quadrature squeezing and quantum state transfer in a hybrid atom-optomechanical cavity with two Duffing mechanical oscillators
In this paper, we investigate theoretically the quantum state transfer in a
laser driven hybrid optomechanical cavity with two Duffing-like anharmonic
movable end mirrors containing an ensemble of identical two-level trapped
atoms. The quantum state transfer from the Bogoliubov modes of the two
anharmonic oscillators to the atomic mode results in the atomic quadrature
squeezing beyond the standard quantum limit of 3 dB which can be controlled by
both the optomechanical and atom-field coupling strengths. Interestingly, the
generated atomic squeezing can be made robust against the noise sources by
means of the Duffing anharmonicity. Moreover, the results reveal that the
presence of the Duffing anharmonicity provides the possibility of transferring
strongly squeezed states between the two mechanical oscillators in a short
operating time and with a high fidelity
Steady-state mechanical squeezing and ground-state cooling of a Duffing anharmonic oscillator in an optomechanical cavity assisted by a nonlinear medium
In this paper, we study theoretically a hybrid optomechanical system
consisting of a degenerate optical parametric amplifier inside a driven optical
cavity with a moving end mirror which is modeled as a stiffening Duffing-like
anharmonic quantum mechanical oscillator. By providing analytical expressions
for the critical values of the system parameters corresponding to the emergence
of the multistability behavior in the steady-state response of the system, we
show that the stiffening mechanical Duffing anharmonicity reduces the width of
the multistability region while the optical parametric nonlinearity can be
exploited to drive the system toward the multistability region. We also show
that for appropriate values of the mechanical anharmonicity strength the
steady-state mechanical squeezing and the ground-state cooling of the
mechanical resonator can be achieved. Moreover, we find that the presence of
the nonlinear gain medium can lead to the improvement of the mechanical
anharmonicity-induced cooling of the mechanical motion, as well as to the
mechanical squeezing beyond the standard quantum limit of 3 dB.Comment: 14 pages, 12 figure
Phase noise and squeezing spectra of the output field of an optical cavity containing an interacting Bose-Einstein condensate
We present a theoretical study of the phase noise, intensity and quadrature
squeezing power spectra of the transmitted field of a driven optical cavity
containing an interacting one-dimensional Bose-Einstein condensate. We show how
the pattern of the output power spectrum of the cavity changes due to the
nonlinear effect of atomic collisions. Furthermore, it is shown that due to a
one-to-one correspondence between the splitting of the peaks in the phase noise
power spectrum of the cavity output field and the \textit{s}-wave scattering
frequency of the atom-atom interaction, one can measure the strength of
interatomic interaction. Besides, we show how the atomic collisions affect the
squeezing behavior of the output field
Generation of nonlinear coherent states in a coherently pumped micromaser under intensity-dependent Jaynes-Cummings model
In this paper the possibility of generating nonlinear coherent states of the
radiation field in a micromaser is explored. It is shown that these states can
be provided in a lossless micromaser cavity under the weak Jaynes-Cummings
interaction with intensity-dependent coupling of large number of individually
injected two-level atoms in a coherent superposition of the upper and lower
states. In particular, we show that the so-called nonlinear squeezed vacuum and
nonlinear squeezed first excited states, as well as the even and odd nonlinear
coherent states can be generated in the presence of two-photon transitions.Comment: 15 page
Controlling steady-state bipartite entanglements and quadrature squeezing in a membrane-in-the-middle optomechanical system with two Bose-Einstein condensates
We study theoretically a driven hybrid optomechanical system with a
membrane-in-the-middle configuration containing two identical elongated
cigar-shaped Bose-Einstein condensates (BECs) in each side of the membrane. In
the weakly interacting regime, the BECs can be considered as single-mode
oscillators in the Bogoliubov approximation which are coupled to the optical
field through the radiation pressure interaction so that they behave as two
quasi-membranes. We show that the degree of squeezing of each BEC and its
entanglement with the moving membrane can be controlled by the \textit{s}-wave
scattering frequency of the other one. Since the \textit{s}-wave frequency of
each BEC depends on the transverse trapping frequency of the atoms which is an
experimentally controllable parameter, one can control the entanglement and
squeezing of each BEC through the trapping frequency of the other one
Dynamical Behaviours of the Nonlinear Atom-Field Interaction in the Presence of Classical Gravity: f-Deformation Approach
In this paper, we investigate the effects of a classical gravitational field
on the dynamical behaviour of nonlinear atom-field interaction within the
framework of the f-deformed Jaynes-Cummings model. For this purpose, we first
introduce a set of new atomic operators obeying an f-deformed su(2) algebraic
structure to derive an effective Hamiltonian for the system under
consideration. Then by solving the Schrodinger equation in the interaction
picture and considering certain initial quantum states for the atomic and
radiation subsystems, we analyze the influence of gravity on the temporal
evolution of the atomic population inversion, atomic dipole squeezing, atomic
momentum diffusion, photon counting statistics, and deformed quadrature
squeezing of the radiation field
Control and manipulation of electromagentically induced transparency in a nonlinear optomechanical system with two movable mirrors
We consider an optomechanical cavity made by two moving mirrors which
contains a Kerr-down conversion nonlinear crystal. We show that the coherent
oscillations of the two mechanical oscil- lators can lead to splitting in the
electromagnetically induced transparency (EIT) resonance, and appearance of an
absorption peak within the transparency window. In this configuration the
coher- ent induced splitting of EIT is similar to driving a hyperfine
transition in an atomic Lambda-type three-level system by a radio-frequency or
microwave field. Also, we show that the presence of non- linearity provides an
additional flexibility for adjusting the width of the transparency windows. The
combination of an additional mechanical mode and the nonlinear crystal suggests
new possibilities for adjusting the resonance frequency, the width and the
spectral positions of the EIT windows as well as the enhancement of the
absorption peak within the transparency window
Generation of motional nonlinear coherent states and their superpositions via intensity-dependent coupling of a cavity field to a micromechanical membrane
We propose a theoretical scheme to show the possibility of generating
motional nonlinear coherent states and their superposition for an undamped
vibrating micromechanical membrane inside an optical cavity. The scheme is
based on an intensity-dependent coupling of the membrane to the radiation
pressure field. We show that if the cavity field is initially prepared in a
Fock state, the motional state of the membrane may evolve from vacuum state to
a special type of nonlinear coherent states. By examining the nonclassical
properties of the generated state of the membrane, including the quadrature
squeezing and the sub-Poissonian statistics, we find that by varying the
Lamb-Dicke parameter and the membrane's reflectivity one can effectively
control those properties. In addition, the scheme offers the possibility of
generating various types of the so-called nonlinear multicomponent Schrodinger
cat sates of the membrane. We also examine the effect of the damping of the
cavity field on the motional state of the membrane
The effect of atomic collisions on the quantum phase transition of a Bose-Einstein condensate inside an optical cavity
In this paper, we investigate the effect of atomic collisions on the phase
transition form the normal to the superradiant phase in a one-dimensional
Bose-Einstein condensate (BEC) trapped inside an optical cavity. Specifically,
we show that driving the atoms from the side of the cavity leads to the
excitation of modes in the edges of the first Brillouin zone of every energy
band, which results in the two-mode approximation of the BEC matter field in
the limit of weak coupling regime. The nonlinear effect of atom-atom
interaction shifts the threshold of the quantum phase transition of the BEC and
also affect the power low behavior of quantum fluctuations in the total
particle number. Besides, we show the possibility of controlling the quantum
phase transition of the system through the s-wave scattering frequency when the
the strength of the transverse pumping has been fixed.Comment: 10 pages, 10 figure
Influence of atomic collisions on spectrum of light scattered from an f-deformed Bose-Einstein condensate
In this paper, we investigate the spectrum of light scattered from a
Bose-Einstein condensate in the framework of f-deformed boson. We use an
f-deformed quantum model in which the Gardiners phonon operators for BEC are
deformed by an operator-valued function, f(n), of the particle-number operator
n. We consider the collisions between the atoms as a special kind of
f-deformation. The collision rate k is regarded as the deformation parameter
and the spectrum of light scattered from the deformed BEC is analyzed. In
particular, we find that with increasing the values of deformation parameters k
and eta=1/N (N, total number of condensate atoms) the scattering spectrum shows
deviation from the spectrum associated with nondeformed Bose-Einstein
condensate.Comment: 17 pages, 4figure
- …