do you want your gadgets to be faster
what if your phone can cut the time it
takes to complete tasks or your computer
can compute way faster most of us do but
with the state of current technology the
truth is they are likely to get much
faster than they are for the past decade
and a half the clock rate of single
processor cores is stalled at a few
gigahertz and it's getting harder to
push the boundaries of the famous
moore's law however a new invention by
ibm may change all of that what are
optical circuits how do they work and
how they make your devices faster
join us as we dive into the new optical
circuit that surpasses every cpu known
to humans what do your brain and a
computer have in common
nothing really however there are
similarities in how the two work for
example your brain contains around 100
billion cells called neurons the tiny
switches that let you think and remember
things in the case of computers they
contain billions of miniature brain
cells the brain cells are known as
transistors and they're made from
silicon a chemical element commonly
found in sand but how does a transistor
work depending on how you look at it and
how much expertise you have in tech a
transistor is simple or complex a
transistor is a miniature electronic
component that can do two different jobs
it can work either as an amplifier or a
switch when it works as an amplifier it
takes a tiny electric current at one end
an input current and produces a much
bigger electric current and output
current at the other in other words it
works as a current booster did you know
hearing aids were among the first uses
of transistors a hearing aid has a tiny
microphone inside that picks up sounds
from the world around you and turns them
into fluctuating electric currents these
are fed into a transistor that boosts
them and powers a tiny loudspeaker so
you can hear a much louder version of
the sounds around you transistors can
also work as switches a tiny electric
current flowing through one part of a
transistor can make a much bigger
current flow through another part of it
or you can say the small current
switches on the larger one this is
basically how all computer chips work
for instance a memory chip contains
hundreds of millions or even billions of
transistors which can be switched on or
off individually since each transistor
can be in two distinct states it can
store two different numbers zero and one
by piling billions of transistors on a
chip it can keep billions of zeros and
ones and almost as many ordinary numbers
and letters or characters transistors
are made from silicon which does not
typically conduct electricity silicon is
a semiconductor which means it's neither
really a conductor nor an insulator but
how do transistors work inside say your
computer you can put a few transistor
switches together to make something
called a logic gate which compares
several input currents and gives
different outputs logic gates let
computers make straightforward decisions
using a mathematical technique called
boolean algebra unless you are keen on
designing your own computer the
explanation doesn't get simpler than
that
however there is a problem with
transistors most people have heard of
moore's law and axiom by gordon moore
one of the co-founders of intel the law
suggests that electronic devices double
in speed and capability about every two
years and indeed every year tech
companies come up with newer faster
smarter and better gadgets however can
we keep reducing the size of transistors
indefinitely
at present companies like intel are mass
producing transistors
14 nanometers across or just 14 times
wider than dna molecules that feat is
thanks to silicon which transistors are
made of silicon's atomic size is about
0.2 nanometers today's transistors are
about 70 silicon atoms wide so the
possibility of making them even smaller
is itself shrinking the undeniable truth
is that we're getting very close to the
limit of how small we can make a
transistor so how can we continue to get
more performance out of our gadgets
this is where optical circuits come in
an international research team led by
ibm and skulltech has created a highly
energy efficient optical switch that
could replace electronic transistors in
a new generation of computers
manipulating photons rather than
electrons in addition to direct power
saving the switch requires no cooling
and is fast at 100 trillion operations
per second it's between 100 and 1000
times faster than today's top-notch
commercial transistors most modern
electrical transistors take tens of
times more energy to switch and the ones
that use single electrons to achieve
comparable efficiencies are way slower
besides performance issues the competing
power saving electronic transistors also
tend to require bulky cooling equipment
which consumes power and factors into
the operating costs the new switch
conveniently works at room temperature
and circumvents all these problems in
addition to its primary transistor light
function the switch could act as a
component that links devices by
shuttling data between them in the form
of optical signals it can also serve as
an amplifier boosting the intensity of
an incoming laser beam by a factor of up
to 23 000
so how does an optical transistor work
the device relies on two lasers to set
its state to zero or one and switch
between them a very weak control laser
beam is used to turn another brighter
laser beam on or off it only takes a few
photons in the control beam which is why
the device is so efficient the switching
occurs inside a micro cavity that is a
35 nanometer thin organic semiconducting
polymer sandwiched between highly
reflective inorganic structures the
micro cavities built in such a way is to
keep incoming light trapped inside for
as long as possible to favor its
coupling with the cavities material when
photons couple strongly to bound
electron hole pairs or exitons in the
cavities material this gives rise to
short-lived exciton polarotoms a kind of
quasi-particles at the heart of the
switch's operation
when the pump laser that is the brighter
one of the two shines on the switch this
creates thousands of identical
quasi-particles in the exact location
forming so-called bose-einstein
condensate which encodes the zero and
one logic states of the device
to switch between the two levels of the
device the research team used a control
laser pulse seeding the condensate
shortly before the arrival of the pump
laser pulse as a result it stimulates
energy conversion from the pump laser
boosting the number of quasi particles
in the condensate the high amount of
particles in there corresponds to the
one state of the device the researchers
used several tweaks to ensure low power
consumption first efficient switching
was aided by the vibrations of the
semiconducting polymers molecules the
trick was to match the energy gap
between the pumped states and the
condensate state to the energy of one
particular molecular vibration in the
polymer second the team managed to find
the optimal wavelength to tune their
laser to and implemented a new
measurement scheme enabling single shot
condensate detection
third the control laser seeding the
condensate and its detection scheme was
matched in a way that suppressed the
noise from the device's background
emission these measures maximized the
signal-to-noise level of the device and
prevented an excess of energy from being
absorbed by the micro-cavity which would
only serve to heat it up through
molecular vibrations
one challenge the team faced was the
ability of silicon to absorb visible
light while necessary for capturing
sunlight in solar panels this is not
great for a waveguide where light
absorption means signal loss to deal
with the absorption issue the
researchers opted for nanostructures
called high contrast gratings such a
grating consists of nanometer-sized
posts lined up to form a fence that
prevents light from escaping the posts
are 115 nanometers in diameter the
spacer that light passing through them
interferes destructively with light
passing between them there is still some
work ahead of the team to lower the
overall power consumption of the device
which is currently dominated by the pump
laser that keeps the switch on a route
toward that goal could be perovskite
supercrystal materials they're exploring
with collaborators they have proven
excellent candidates given their strong
light matter coupling which in turn
leads to a powerful collective quantum
response in the form of super
fluorescence
let's hear what you think of the new
optical circuit in the comment section
below