Quantum-dot Cellular Automata

rucksackbulgeΤεχνίτη Νοημοσύνη και Ρομποτική

1 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

88 εμφανίσεις

Clocked Molecular
Quantum
-
dot Cellular
Automata

A NEW COMPUTATIONAL
PARADIGM

Gabriele Dura

Clocked

Molecular Quantum
-
dot
Cellular Automata

Recent computation is achieved thanks to
the enormous number of C
-
MOS per area


Now there is a problem to continue this
trend

Clocked Molecular Quantum
-
dot
Cellular Automata

The Moore’s Law

Clocked Molecular Quantum
-
dot
Cellular Automata

It is necessary a new computational
paradigm



Quantum
-
dot Cellular Automata


Clocked Molecular Quantum
-
dot
Cellular Automata

What is it?

Clocked Molecular Quantum
-
dot
Cellular Automata

How to use it?

We can make quantum wire


Quantum inverter


Quantum Majority Gate


Quantum fanout

Clocked Molecular Quantum
-
dot
Cellular Automata

How does it work?


Every cell has two extra charge, that could
be electrons or holes.

Coulombic interaction between this extra
charge will achieve a ground state in the
cell, moving in the cell by tunneling

The two extra charges are confined in the
cells by a high potential barrier.



Clocked Molecular Quantum
-
dot
Cellular Automata

These devices have some problems:


1.
Too low working temperature (4
°
K)


2.
A metastable configuration
with long life time

can
be achieved



ERROR IN COMPUTATION


3.
High sensitiity to the position cell
-
to
-
cell (showing by
simulation)


How to solve this problem:


Temperature

Molecular Quantum
-
dot
cells

Metastable configuration


four phase
clock and quasi
-
adiabatic transition

Imperfections


actually there is no
indication about (only simulation)

Clocked Molecular Quantum
-
dot
Cellular Automata

Clocked Molecular Quantum
-
dot
Cellular Automata

Molecular quantum
-
dot proposed by


Lent


Isakcsen




Allyl










Alkyl

Clocked Molecular Quantum
-
dot
Cellular Automata

Allyl groups serve
as dots with his red
-
ox centre that can
be achieved cy halls

Alkyl groups serve
as tunnel barrier that
halls can pass
through


Clocked Molecular Quantum
-
dot
Cellular Automata

Molecule was driven by a

driver dipole






and






clocked by a perpendicular electric field





This give a highly nonlinear dipole




moment


6.6
Å

Clocked Molecular Quantum
-
dot
Cellular Automata

Molecular Quantum
-
dot Cell

Clocked Molecular Quantum
-
dot
Cellular Automata

It is possible to enable the
clock in this device using
some buried wires


The current flow through
wires generates an Electric
Field that drives the state of
the molecule


Clocked Molecular Quantum
-
dot
Cellular Automata


Clock must have four
-
phase that allows

quasi
-
adiabatic interaction cell
-
to
-
cell

















Applied Signal Value of Electric Field Electric Field Distribution






That implies this “truth table”






Clocked Molecular Quantum
-
dot
Cellular Automata

Influence of imperfection on the dynamical response in QCA

Nowadays only considered in model simulations.


Ideal chain of cells:



Imperfection introduced between

the fifth and the sixth



the third and the fourth the driver and the chain











Correct polarization



Acceptable polarization


Capability whole disappears

Clocked Molecular Quantum
-
dot
Cellular Automata

Imperfection due to interdot distance defects


Imperfection introduced in the interdot barriers in the second cells
















Dependence of the output cell
Response of polarization with this imperfection


on the tunneling parameter L
1







in the second cell of this chain

Clocked Molecular Quantum
-
dot
Cellular Automata

Imperfection due to interdot distance defects

Imperfection introduced in the interdot barriers in the middle cell






Imperfection introduced in the interdot barriers in the last cell

Clocked Molecular Quantum
-
dot
Cellular Automata



Conclusion:


We can see that Molecular Quantum
-
dot
Cellular Automata produce a highly non
-
linear characteristic that can be used to
get something like logic gates with a very
low power dissipation and very high device
densities.

Clocked Molecular Quantum
-
dot
Cellular Automata

L

Conclusion:


There is too much work to do to design a
good real device that can operate at room
temperature and can resist to the
imperfections occurring in the industrial
process for large scale diffusion
.