8,317 research outputs found
Coherent-feedback-induced photon blockade and optical bistability by an optomechanical controller
It is well-known that some nonlinear phenomena such as strong photon blockade
are hard to be observed in optomechanical system with current experimental
technology. Here, we present a coherent feedback control strategy in which a
linear cavity is coherently controlled by an optomechanical controller in a
feedback manner. The coherent feedback loop transfers and enhances quantum
nonlinearity from the controller to the controlled cavity, which makes it
possible to observe strong nonlinear effects in either linear cavity or
optomechanical cavity. More interestingly, we find that the strong photon
blockade under single-photon optomechanical weak coupling condition could be
observed in the quantum regime. Additionally, the coherent feedback loop leads
to two-photon and multiphoton tunnelings for the controlled linear cavity,
which are also typical quantum nonlinear phenomenon. We hope that our work can
give new perspectives in engineering nonlinear quantum phenomena.Comment: 12 pages, 11 figure
Phononic Josephson oscillation and self-trapping with two-phonon exchange interaction
We propose a bosonic Josephson junction (BJJ) in two nonlinear mechanical
resonator coupled through two-phonon exchange interaction induced by quadratic
optomechanical couplings. The nonlinear dynamic equations and effective
Hamiltonian are derived to describe behaviors of the BJJ. We show that the BJJ
can work in two different dynamical regimes: Josephson oscillation and
macroscopic self-trapping. The system can transfer from one regime to the other
one when the self-interaction and asymmetric parameters exceed their critical
values. We predict that a transition from Josephson oscillation to macroscopic
self-trapping can be induced by the phonon damping in the asymmetric BJJs. Our
results opens up a way to demonstrate BJJ with two-phonon exchange interaction
and can be applied to other systems, such as the optical and microwave systems.Comment: 7 pages, 7 figure
Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation
The interaction between the radiation field in a microcavity with a mirror
undergoing damping oscillation is investigated. Under the heavily damping
cases, the mirror variables are adiabatically eliminated.
The the stationary conditions of the system are discussed. The small
fluctuation approximation around steady values is applied to analysis the
antibunching effect of the cavity field. The antibunching condition is given
under two limit cases.Comment: 5 pages, no figur
Mechanically modulated emission spectra and blockade of polaritons
We study a hybrid semiconductor-optomechanical system, which consists of a
cavity with an oscillating mirror made by semiconducting materials or with a
semiconducting membrane inside. The cavity photons and the excitons in the
oscillating mirror or semiconducting membrane form into polaritons. And
correspondingly, the optomechanical interaction between the cavity photons and
the mirror or membrane is changed into the polariton-mechanical interaction. We
theoretically study the eigenenergies and eigenfunctions of this tripartite
hybrid system with the generalized rotating-wave approximation. We show that
the emission spectrum of polariton mode is modulated by the mechanical
resonator. We also study the mechanical effect on the statistical properties of
the polariton when the cavity is driven by a weak classical field. This work
provides a detailed description of the rich nonlinearity owing to the
competition between parametric coupling and three-wave mixing interaction
concerning the polariton modes and the phonon mode. It also offers a way to
operate the photons, phonons and excitons, e.g., detect the properties of
mechanical resonator through the fine spectra of the polaritons or control the
transmission of light in the integrated semiconducting-optomechanical platform
Generating nonclassical photon-states via longitudinal couplings between superconducting qubits and microwave fields
Besides the conventional transverse couplings between superconducting qubits
(SQs) and electromagnetic fields, there are additional longitudinal couplings
when the inversion symmetry of the potential energies of the SQs is broken. We
study nonclassical-state generation in a SQ which is driven by a classical
field and coupled to a single-mode microwave field. We find that the classical
field can induce transitions between two energy levels of the SQs, which either
generate or annihilate, in a controllable way, different photon numbers of the
cavity field. The effective Hamiltonians of these classical-field-assisted
multiphoton processes of the single-mode cavity field are very similar to those
for cold ions, confined to a coaxial RF-ion trap and driven by a classical
field. We show that arbitrary superpositions of Fock states can be more
efficiently generated using these controllable multiphoton transitions, in
contrast to the single-photon resonant transition when there is only a SQ-field
transverse coupling. The experimental feasibility for different SQs is also
discussed.Comment: 15 pages, 8 figure
Backlund transformations for Burgers Equation via localization of residual symmetries
In this paper, we obtained the non-local residual symmetry related to
truncated Painlev\'e expansion of Burgers equation. In order to localize the
residual symmetry, we introduced new variables to prolong the original Burgers
equation into a new system. By using Lie's first theorem, we got the finite
transformation for the localized residual symmetry. More importantly, we also
localized the linear superposition of multiple residual symmetries to find the
corresponding finite transformations. It is interesting to find that the nth
Backlund transformation for Burgers equation can be expressed by determinants
in a compact way
Tunable Electromagnetically Induced Transparency and Absorption with Dressed Superconducting Qubits
Electromagnetically induced transparency and absorption (EIT and EIA) are
usually demonstrated by three-level atomic or atom-like systems. In contrast to
the usual case, we theoretically study the EIT and EIA in an equivalent
three-level system, which is constructed by dressing a superconducting
two-level system (qubit) dressed by a single-mode cavity field. In this
equivalent system, we find that both the EIT and the EIA can be tuned by
controlling the level-spacing of the superconducting qubit and hence
controlling the dressed system. This tunability is due to the dressed
relaxation and dephasing rates which vary parametrically with the level-spacing
of the original qubit and thus affect the transition properties of the dressed
qubit and the susceptibility. These dressed relaxation and dephasing rates
characterize the reaction of the dressed qubit to an incident probe field. We
also use recent experimental data on superconducting qubits (charge, phase, and
flux qubits) to demonstrate our approach and show the possibility of
experimentally realizing this proposal.Comment: 13 page
New interaction solutions of Kadomtsev-Petviashvili equation
The residual symmetry coming from truncated Painleve expansion of KP equation
is nonlocal, which is localized in this paper by introducing multiple new
dependent variables. By using the standard Lie group approach, the symmetry
reduction solutions for KP equation is obtained based on the general form of
Lie point symmetry for the prolonged system. In this way, the interaction
solutions between solitons and background waves is obtained, which is hard to
study by other traditional methods
New symmetry reductions related with the residual symmetry of Boussinesq equation
The Backlund transformation related symmetry is nonlocal, which is hardly to
apply in constructing solutions for nonlinear equations. In this paper, we
first localize nonlocal residual symmetry to Lie point symmetry by introducing
multiple new variables and obtain new Baaklund transformation. Then, by solving
out the general form of localized the residual symmetry, we reduce the enlarged
system by classical symmetry approach and obtain the corresponding reduction
solutions as well as related reduction equations. The localization procedure
provides a new way to investigate interaction solutions between different
waves
Single-photon nonreciprocal transport in one-dimensional coupled-resonator waveguides
We study the transport of a single photon in two coupled one-dimensional
semi-infinite coupled-resonator waveguides (CRWs), in which both end sides are
coupled to a dissipative cavity. We demonstrate that a single photon can
transfer from one semi-infinite CRW to the other nonreciprocally. Based on such
nonreciprocity, we further construct a three-port single-photon circulator by a
T-shaped waveguide, in which three semi-infinite CRWs are pairwise mutually
coupled to each other. The single-photon nonreciprocal transport is induced by
the breaking of the time-reversal symmetry and the optimal conditions for these
phenomena are obtained analytically. The CRWs with broken time-reversal
symmetry will open up a kind of quantum devices with versatile applications in
quantum networks.Comment: 10 pages, 6 figure
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