Today's computers can do a lot, but it seems the more you ask of them, the
slower they get, and when it comes to
certain things, classical computers start
to fall short.
That's why physicists have proposed the
quantum computer. Unlike classical
computers these use quantum bits or
qubits for short. A 'bit' is a unit of
information with two states often
represented as 1 or 0. whereas a classical bit must be in either state at any
given time, a qubit's state can be any
proportion of the two states--being some
degree of both at the same time. This
intermediary state is called a
"superposition." The catch is: any attempt to measure a superposition will cause it
to decohere. In other words, the qubit
will randomly assume one of its primary
states--most likely the one closest to the
superposition. So what's so different
about computing with qubits. Fact of the
matter is, a lot more information can be
contained in a lot less qubits. You can
create four distinct states with two
bits. Yet, classical bits can only be in
one of these states at a time. Now
looking at two qubits, because both are
in a superposition of state one and
state zero, a single state contains all
four of the previous classical. Quantum
computers can answer certain problems
in a lot less steps by performing
operations on multiple states in
parallel. So why don't we all have QuPhones and quantum
core processors in our laptops. Fact is, qubits aren't the most stable of
things. They can be easily corrected by
noise. And what's noise? . . . Let's see!
Loud isn't it?
Wrong noise.
That's better! Quantum noise is those
factors that create uncertainty in a
system. Remember, a bit can be a variety
of two systems. In the same vein, a qubit
can be any quantum mechanical system
with two levels, like the spin of an
electron. So, yeah! An old jazz band can be quantum noise, but when working in the
quantum realm, bits are so microscopic that even a photon can decohere a superposition.
Even observing a superposition, decoheres it. Think of this room as a quantum computer
and these guys as logic gates--each
performing some operation with the
potential to alter a bit. Now say
something were to disrupt a qubit
midway through. The remaining operations aren't being performed on a superposition
but rather a decohered state--
corrupting your output. So the current
solution? Keep the computers clean colder than space and hope for the best.
But!! There may be a better way to protect
information than just shielding it:
breaking it down! Instead of qubits being
a single particle containing a system,
consider a system comprised of multiple
particles. Anyons are two-dimensional
quasiparticles. And the state of an
anyon system is determined by how those
particles are spatially configured. Thus
swapping particle positions creates a
distinct new state. If we graph the
position of these anyons versus the
passage of time, we see their world lines
begin to braid. If you were to encode
information into the system, then each
braid constitutes an operation.
This is a multi-body system, and information is realized when you bring the pieces
together. If a single particle gets a
little noisy, then there won't be any
decoherence because no lone particle
carries isolated information. It may seem
small scale but the next huge leap in
computing may just be . . .
~ noise cancellation. ~
