A quantum computer is built using "qubits" which are essentially two-state devices that can also be in a linear combination of "0" and "1". Maybe you heard of Schroedings cat? The cat behaves as a qubit.
A quantum computer behaves somewhat like parellel computers in the sense that can operate on ALL possible combination of 0 and 1 at once.
About "trapping of light": The first rule of physics is to make sure that whatever it is you are doing, make sure to mention it might be useful for quantum computing when you apply for money😉
Here is a slightly longer explanation of the idea of qubit.
It is in Latex-format but I think it is readable
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One application of superconductivity that has received a lot of attention over the past few years is the
\textit{superconducting qubit}. The qubit -short for \textbf{qu}antum \textbf{bit}- can be though of as a simple
"artificial atom" that can be controlled in such a way that it can be used as the basic building block of a
quantum computer, a machine originally proposed by theorists such as Feynmann in the 1970s and early 1980.
The quantum computer is in essence a computer that takes advantage of the possibility of having a two-state system in
a "Schrödinger's cat state". The name refers to a famous thought-experiment where a cat is e.g. poisoned with 50\%
probability as a consequence of some "quantum event" (originally the radioactive decay of a nucleus).
According to classical physics we would expect that the cat would either die or survive the experiment, however quantum
mechanics tells us that it is in fact possible for the cat to be in a state which is a \textit{superposition} of dead
\textit{and} alive. This is of course an apparent paradox, but it turns out to be in essence correct.
The quantum computer uses superposition to perform certain types of calculations very fast, much faster than what
is possible with a conventional computer. In a quantum computers the qubits have the job of the "cats" and are
two-state systems that are coupled to each other. If we denote the "alive" and "dead" states of our qubits by $|0>$ and
$|1>$ we can write the state at any time as $|\Psi>=a|0>+b|1>$ where $a$ and $b$ be are complex numbers normalized so that
$a^2+b^2=1$. Now, if we couple two qubits together we can denote their states as $|00>$, $|01>$, $|10>$ and $|11>$; this is similar
to a two bit register but due to the possibility of superposition we can also have e.g. the state $0.5(|00>+|01>+|10>+|11>$
representing all four classical states at once.
In 1994 Peter Shor \cite{shor} presented what is now known as Shor's algorithm which uses a quantum computer to factorize very large numbers, an important problem
in mathematics. In 2001 Vandersypen et al. \cite{vandersypen} implemented Shor's algorithm using a 7-qubit NMR-based
quantum computer, this was of course a triumph for qubit-implementations using "real" atoms and molecules but it
stretched the technology to the limit. There is today a broad consensus that the only way to build a \textit{useful} quantum
computer is to use solid state technology which can be manipulated and designed in ways impossible with e.g. molecules.
