Information Technology Reference
In-Depth Information
This effect is known as
Decoherence
. To provide an insight into this phenomenon,
an application called QDsim was created.
QDsim is a numerical application designed to study the quantum dynamics
of concurrence for a bipartite system composed of two quantum dots under
external interactions. It is important to highlight that the concurrence is the
best known indirect measurement of entanglement
1
of any bipartite system. By
using the density operator Master Equation (ME), QDsim is able to compute
the concurrence in the bipartite system using the analytical formula derived by
Wootters[2].
Electromagnetic radiations from any source, can produce a series of resonant
effects inside the quantum cavity (where the QDs are embedded) thus causing
interactions. Furthermore, even the laser beam used to control the operation
of the QD may cause such interactions. The aforementioned resonant effect is
composed of infinite light modes (Fock states) or degrees of freedom that perturb
the quantum state of the QDs. For this reason, solving this kind of system is a
time-consuming task; from hours to even days.
This paper thus proposes an algorithm to solve Wootters Concurrence using
parallel techniques that runs over a Beowulf-like cluster composed of shared
memory processors in order to reduce the processing time. Section 2 gives a
brief introduction of the quantum system, sections 3, 4 and 5 show how the
computation was parallelized, and finally sections 6, 7 and 8 discuss the results
and how performance was measured.
2Sy emMod l
Using the analogy of the binary representation, where bits (represented by “0”
logic and “1” logic) are the cornerstone of the information in classical compu-
tation, excitonic states are the foundation of the quantum information through
quantum bits or Qbits. The model under study has two QDs embedded in a
three dimensional semiconductor microcavity as shown schematically in Fig. 1.
Qbits have two levels: the first, represented by
|
0
, corresponds to the absence
|
of excitons; on the other hand, the
1
state indicates the presence of excitons.
Fig. 1.
Model of a QD into quantum cavity taken from [3]
1
A phenomenon in which the quantum states of two or more QDs are correlated.
