6,153 research outputs found
Accelerating adiabatic quantum transfer for three-level -type structure systems via picture transformation
In this paper, we investigate the quantum transfer for the system with
three-level -type structure, and construct a shortcut to the adiabatic
passage via picture transformation to speed up the evolution. We can design the
pulses directly without any additional couplings. Moreover, by choosing
suitable control parameters, the Rabi frequencies of pulses can be expressed by
the linear superpositions of Gaussian functions, which could be easily realized
in experiments. Compared with the previous works using the stimulated Raman
adiabatic passage, the quantum transfer can be significantly accelerated with
the present scheme.Comment: 16 pages, 5 figures, has been accepted by Annals of Physic
Optimal shortcut approach based on an easily obtained intermediate Hamiltonian
We present a general approach to speed up the adiabatic process without
adding the traditional counterdiabatic driving (CD) Hamiltonian. The strategy
is to design an easy-to-get intermediate Hamiltonian to connect the original
Hamiltonian and final transitionless Hamiltonian. With final transitionless
Hamiltonian, the same target can be achieved as in the adiabatic process
governed by the original Hamiltonian, but in a shorter time. We apply the
present approach to a three-level system, and the result shows that the final
transitionless Hamiltonian usually has the same structure as the original
Hamiltonian but with different time-dependent coefficients, allowing speedup to
be achieved in a much easier way compared to previous methods.Comment: 12 pages,8 figures, has been accepted for publication as a Regular
Article in Physical Review
Coherent control in quantum open systems: An approach for accelerating dissipation-based quantum state generation
In this paper, we propose an approach to accelerate the dissipation dynamics
for quantum state generation with Lyapunov control. The strategy is to add
target-state-related coherent control fields into the dissipation process to
intuitively improve the evolution speed. By applying the current approach,
without losing the advantages of dissipation dynamics, the target stationary
states can be generated in a much shorter time as compared to that via
traditional dissipation dynamics. As a result, the current approach containing
the advantages of coherent unitary dynamics and dissipation dynamics allows for
significant improvement in quantum state generation.Comment: 5 pages, 6 figures, has been accepted as a regular article in
Physical Review A and revised according to some suggestion
Arbitrary quantum state engineering in three-state systems via Counterdiabatic driving
A scheme for arbitrary quantum state engineering (QSE) in three-state systems
is proposed. Firstly, starting from a set of complete orthogonal time-dependent
basis with undetermined coefficients, a time-dependent Hamiltonian is derived
via Counterdiabatic driving for the purpose of guiding the system to attain an
arbitrary target state at a predefined time. Then, on request of the assumed
target states, two single-mode driving protocols and a multi-mode driving
protocol are proposed as examples to discuss the validity of the QSE scheme.
The result of comparison between single-mode driving and multi-mode driving
shows that multi-mode driving seems to have a wider rang of application
prospect because it can drive the system to an arbitrary target state from an
arbitrary initial state also at a predefined time even without the use of
microwave fields for the transition between the two ground states. Moreover,
for the purpose of discussion in the scheme's feasibility in practice, a
polynomial ansatz as the simplest exampleis used to fix the pulses. The result
shows that the pulses designed to implement the protocols are not hard to be
realized in practice. At the end, QSE in higher-dimensional systems is also
discussed in brief as a generalization example of the scheme.Comment: 16 pages, 13 figures, has been accepted by Scientific Report
Method for constructing shortcuts to adiabaticity by a substitute of counterdiabatic driving terms
We propose an efficientmethod to construct shortcuts to adiabaticity through
designing a substitute Hamiltonian to try to avoid the defect in which the
speed-up protocol' Hamiltonian may involve terms which are difficult to realize
in practice. We show that as long as the counterdiabatic coupling terms-even
only some of them-have been nullified by the additional Hamiltonian, the
corresponding shortcuts to the adiabatic process could be constructed and the
adiabatic process would be sped up. As an application example, we apply this
method to the popular Landau-Zener model for the realization of fast population
inversion. The results show that in both Hermitian and non-Hermitian systems,
we can design different additional Hamiltonians to replace the traditional
counterdiabatic driving Hamiltonian to speed up the process. This method
provides many choices for designing additional terms of the Hamiltonian such
that one can choose a realizable model in practice.Comment: 11pages, 6 figures, has been accepted for publication as a Regular
Article in Physicial Review
Precise quantum control via unsharp measurements and feedback operations
In this paper, we propose a scheme to eliminate the influence of noises on
system dynamics, by means of a sequential unsharp measurements and unitary
feedback operations. The unsharp measurements are carried out periodically
during system evolution, while the feedback operations are well designed based
on the eigenstates of the density matrices of the exact (noiseless) dynamical
states and its corresponding post-measurement states. For illustrative
examples, we show that the dynamical trajectory errors caused by both static
and non-static noises are successfully eliminated in typical two-level and
multi-level systems, i.e., the high-fidelity quantum dynamics can be
maintained. Furthermore, we discuss the influence of noise strength and
measurement strength on the degree of precise quantum control. Crucially, the
measurement-feedback scheme is quite universal in that it can be applied to
precise quantum control for any dimension systems. Thus, it naturally finds
extensive applications in quantum information processing.Comment: 11 pages, 9 figure
Improving the stimulated Raman adiabatic passage via dissipative quantum dynamics
We propose a method to improve the stimulated Raman adiabatic passage
(STIRAP) via dissipative quantum dynamics, taking into account the dephasing
effects. Fast and robust population transfer can be obtained with the scheme by
the designed pulses and detuning, even though the initial state of the system
is imperfect. With a concrete three-level system as an example, the influences
of the imperfect initial state, variations in the control parameters, and
various dissipation effects are discussed in detail. The numerical simulation
shows that the scheme is insensitive to moderate fluctuations of experimental
parameters and the relatively large dissipation effects of the excited state.
Furthermore, the dominant dissipative factors, namely, the dephasing effects of
the ground states and the imperfect initial state are no longer undesirable, in
fact, they are the important resources to the scheme. Therefore, the scheme
could provide more choices for the realization of the complete population
transfer in the strong dissipative fieldsComment: 8 pages, 10 figures, has been accepted by Optics Expres
Fast quantum state engineering via universal SU(2) transformation
We introduce a simple yet versatile protocol to inverse engineer the
time-dependent Hamiltonian in two- and three level systems. In the protocol, by
utilizing a universal SU(2) transformation, a given speedup goal can be
obtained with large freedom to select the control parameters. As an
illustration example, the protocol is applied to perform population transfer
between nitrogen-vacancy (NV) centers in diamond. Numerical simulation shows
that the speed of the present protocol is fast compared with that of the
adiabatic process. Moreover, the protocol is also tolerant to decoherence and
experimental parameter fluctuations. Therefore, the protocol may be useful for
designing an experimental feasible Hamiltonian to engineer a quantum system.Comment: 11 pages, 8 figures, has been accepted by Physical Review
Improving shortcuts to non-Hermitian adiabaticity for fast population transfer in open quantum systems
It is still a challenge to experimentally realize shortcuts to adiabaticity
(STA) for a non-Hermitian quantum system since a non-Hermitian quantum system's
counterdiabatic driving Hamiltonian contains some unrealizable auxiliary
control fields. In this paper, we relax the strict condition in constructing
STA and propose a method to redesign a realizable supplementary Hamiltonian to
construct non-Hermitian STA. The redesigned supplementary Hamiltonian can be
eithersymmetric or asymmetric. For the sake of clearness, we apply this method
to an Allen-Eberly model as an example to verify the validity of the optimized
non-Hermitian STA. The numerical simulation demonstrates that a ultrafast
population inversion could be realized in a two-level non-Hermitian system.Comment: 11 pages, 4 figures, has been accepted by Annalen Der Physi
Invariant-based inverse engineering for fluctuation transfer between membranes in an optomechanical cavity system
In this paper, by invariant-based inverse engineering, we design classical
driving fields to transfer quantum fluctuations between two suspended membranes
in an optomechanical cavity system. The transfer can be quickly attained
through a non-adiabatic evolution path determined by a so-called dynamical
invariant. Such an evolution path allows one to optimize the occupancies of the
unstable "intermediate" states thus the influence of cavity decays can be
suppressed. Numerical simulation demonstrates that a perfect fluctuation
transfer between two membranes can be rapidly achieved in one step, and the
transfer is robust to both the amplitude noises and cavity decays.Comment: 10 pages, 4 figures, has been accepted by Physical Review
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