72 research outputs found
Generators of nonclassical states by combination of the linear coupling of boson modes, Kerr nonlinearity and the strong linear losses
We show that the generators of quantum states of light can be built by
employing the Kerr nonlinearity, a strong linear absorption or losses and the
linear coupling of optical modes. Our setup can be realized, for instance, with
the use of the optical fiber technology. We consider in detail the simplest
cases of three and four coupled modes, where a strongly lossy mode is linearly
coupled to other linear and nonlinear modes. In the three-mode design, our
scheme emulates the third-order nonlinear absorption, allowing for generation
of the single photon states, or the two-photon absorption allowing to generate
the phase states. In the four-mode design, the scheme emulates a non-local
absorption which produces an entangled state of two uncoupled modes. We also
note that in the latter case and in the case of the phase states generation the
output state is in the linear modes, which prevents its subsequent degradation
by the strong losses accompanying the strong Kerr nonlinearity.Comment: 10 pages, 4 figures; typos in the text and figures were correcte
Nonlinear dissipation can combat linear loss
We demonstrate that it is possible to compensate for effects of strong linear
loss when generating non-classical states by engineered nonlinear dissipation.
We show that it is always possible to construct such a loss-resistant
dissipative gadget in which, for a certain class of initial states, the desired
non-classical pure state can be attained within a particular time interval with
an arbitrary precision. Further we demonstrate that an arbitrarily large linear
loss can still be compensated by a sufficiently strong coherent or even thermal
driving, thus attaining a strongly non-classical (in particular,
sub-Poissonian) stationary mixed states.Comment: Submitted to PR
Quantum tight-binding chains with dissipative coupling
We present a one-dimensional tight-binding chain of two-level systems coupled
only through common dissipative Markovian reservoirs. This quantum chain can
demonstrate anomalous thermodynamic behavior contradicting Fourier law.
Population dynamics of individual systems of the chain is polynomial with the
order determined by the initial state of the chain. The chain can simulate
classically hard problems, such as multi-dimensional random walks
Nonlinear coherent loss for generating non-classical states
Here we discuss generation of non-classical states of bosonic mode with the
help of artificially designed loss, namely the nonlinear coherent loss. We show
how to generate superpositions of Fock states, and how it is possible to "comb"
the initial states leaving only states with certain properties in the resulting
superposition (for example, a generation of a superposition of Fock states with
odd number of particles). We discuss purity of generated states and estimate
maximal achievable generation fidelity
The three-site Bose-Hubbard model subject to atom losses: the boson-pair dissipation channel and failure of the mean-field approach
We employ the perturbation series expansion for derivation of the reduced
master equations for the three-site Bose-Hubbard model subject to strong atom
losses from the central site. The model describes a condensate trapped in a
triple-well potential subject to externally controlled removal of atoms. We
find that the -phase state of the coherent superposition between the side
wells decays via two dissipation channels, the single-boson channel (similar to
the externally applied dissipation) and the boson-pair channel. The quantum
derivation is compared to the classical adiabatic elimination within the
mean-field approximation. We find that the boson-pair dissipation channel is
not captured by the mean-field model, whereas the single-boson channel is
described by it. Moreover, there is a matching condition between the zero-point
energy bias of the side wells and the nonlinear interaction parameter which
separates the regions where either the single-boson or the boson-pair
dissipation channel dominate. Our results indicate that the -site
Bose-Hubbard models, for , subject to atom losses may require an analysis
which goes beyond the usual mean-field approximation for correct description of
their dissipative features. This is an important result in view of the recent
experimental works on the single site addressability of condensates trapped in
optical lattices.Comment: 9 pages; 3 figures in color; submitted to PR
Driving-dependent damping of Rabi oscillations in two-level semiconductor systems
We propose a mechanism to explain the nature of the damping of Rabi
oscillations with increasing driving-pulse area in localized semiconductor
systems, and have suggested a general approach which describes a coherently
driven two-level system interacting with a dephasing reservoir. Present
calculations show that the non-Markovian character of the reservoir leads to
the dependence of the dephasing rate on the driving-field intensity, as
observed experimentally. Moreover, we have shown that the damping of Rabi
oscillations might occur as a result of different dephasing mechanisms for both
stationary and non-stationary effects due to coupling to the environment.
Present calculated results are found in quite good agreement with available
experimental measurements
Plasmon polaritons in photonic superlattices containing a left-handed material
We analyze one-dimensional photonic superlattices which alternate layers of
air and a left-handed material. We assume Drude-type dispersive responses for
the dielectric permittivity and magnetic permeability of the left-handed
material. Maxwell's equations and the transfer-matrix technique are used to
derive the dispersion relation for the propagation of obliquely incident
optical fields. The photonic dispersion indicates that the growth-direction
component of the electric (or magnetic) field leads to the propagation of
electric (or magnetic) plasmon polaritons, for either TE or TM configurations.
Furthermore, we show that if the plasma frequency is chosen within the photonic
zeroth-order bandgap, the coupling of light with plasmons
weakens considerably. As light propagation is forbidden in that particular
frequency region, the plasmon-polariton mode reduces to a pure plasmon mode.Comment: 4 pages, 4 figure
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