Physics Letters A 372 (2008) 7086–7090
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Physics Letters A
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Infrared-light propagation and storing through two lateral tunnel-coupled
InGaAs/GaAs quantum dots
Jiahua Li
a
,∗
,RongYu
b
, Anshou Zheng
c
,XiaoxueYang
a
a
Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China
b
School of Science, Wuhan Institute of Technology, Wuhan 430073, People’s Republic of China
c
College of Mathematics and Physics, China University of Geosciences, Wuhan 430074, People’s Republic of China
article info abstract
Article history:
Received 11 August 2008
Received in revised form 12 October 2008
Accepted 15 October 2008
Availableonline22October2008
Communicated by R. Wu
PACS:
78.67.Hc
42.65.Sf
42.50.Gy
Keywords:
IR light
Storing and retrieving
Semiconductor double-quantum-dot (SDQD)
Dynamic propagation and storing-retrieving of a weak infrared (IR)-light pulse in a coupled semiconduc-
tor double-quantum-dot (SDQD) structure are studied theoretically with feasible parameters. Two
characteristic features are found. First, it is shown that, with a constant control field, the SDQD medium
is transparent to the probe pulse which propagates over sufficiently long distances. Furthermore, the
pulse shape remains unchanged on propagation. Second, with a time-varying control field, we are able
to store and retrieve the probe pulse in this four-subband SDQD medium by adiabatically switching
off and on the control field. Such a four-subband SDQD system for storing and retrieving coherent
information is much more practical than its atomic counterpart as a result of its flexible design and
the controllable (tunable) interference strength and thus provides a new possibility for technological
applications in quantum information science in the SDQD solid-state nanostructure.
©
2008 Elsevier B.V. All rights reserved.
In recent years much attention has been devoted to the real-
ization of controllable light propagation in coherently driven me-
dia [1–3]. Coherently driven, three-level
Λ
-type atoms, instead of
two-level atoms, are widely used to study a variety of new quan-
tum optical phenomena in which the dynamics of a weak probe
(signal) pulse can be efficiently controlled in time by a strong
control field. One of the most important aspects is the modifica-
tion of the absorption, dispersion, and nonlinearity of the system
due to quantum coherence and interference, such as electromag-
netically induced transparency (EIT) [4,5].Inparticular,amedium
transparent due to EIT can be made opaque after the pulse has en-
tered it, by switching the control field off. The signal pulse is thus
“stopped” or rather stored in the form of an atomic excitation and
can be released by switching the control field on after some time
[2,6,7]. The phenomenon of light storage has become the subject of
a vivid interest in the context of potential applications to quantum
information processing.
Based on quantum coherence and interference, the time-
dependent propagation effects which may include storage and
retrieval of light pulses [2,6,7], creation of matched pulses [8,9],
ultraslow optical solitons [10], all-optical switches [11–14], and
*
Corresponding author. Tel.: +86 2787557477; fax: +86 2787557477.
E-mail address: ai_li@126.com (J. Li).
highly efficient frequency conversion in ultraslow propagation
regime [15–20], have shown their great potential in possible op-
toelectronic applications. After having been successful in atomic
systems, theoretical and experimental studies on nonlinear opti-
cal properties of interband/intersubband transitions (IBTs/ISBTs) in
semiconductor quantum wells (QWs) [21–27] have become an in-
teresting topic in the recent years.
Besides the above-mentioned systems, there has also been in-
creasing interest in quantum coherence using quantum dots (QDs)
[28–34], because of reports of long dephasing times and preser-
vation of atomic-like properties (e.g., discrete energy levels) at
high temperatures, ease of integration, and large bandwidth due
to fast carrier dynamics. Several ideas for quantum coherence in
QDs have been proposed and analyzed. For instance, Ku et al. pro-
posed a semiconductor optical buffer using EIT in a QD medium
and theoretically predicted its performance of slow light [33].
Villas-Bôas et al. demonstrated coherent control of tunneling in
an asymmetric double QD system [34]. Recently, the interaction
of electrons confined in double QD structures with external elec-
tromagnetic driving fields has attracted growing attention [35–42].
Several interesting phenomena have been recognized when the QD
structure contains one or two electrons. Examples include con-
trolled transfer of electrons between the two QDs [35–38] and
creation of maximally entangled states in two-electron QD systems
[39–42].
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©
2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.physleta.2008.10.036