Theoretically, quantum computing offers the possibility of factoring the
products of large prime numbers and calculating discreet logarithms in
polynomial time. These calculations can be accomplished in such a
compressed time frame because:

A.
A quantum computer takes advantage of quantum tunneling in
molecular scale transistors. This mode permits ultra high-speed
switching to take place, thus, exponentially increasing the speed of
computations.

B.
Information can be transformed into quantum light waves that
travel through fiber optic channels. Computations can be performed
on the associated data by passing the light waves through various
types of optical filters and solid-state materials with varying indices
of refraction, thus drastically increasing the throughput over
conventional computations.

C.
A quantum computer exploits the time-space relationship that
changes as particles approach the speed of light. At that interface,
the resistance of conducting materials effectively is zero and
exponential speed computations are possible.

D.
A quantum bit in a quantum computer is actually a linear
superposition of both the one and zero states and, therefore, can
theoretically represent both values in parallel. This phenomenon
allows computation that usually takes exponential time to be
accomplished in polynomial time since different values of the binary
pattern of the solution can be calculated simultaneously.

Explanation:
In digital computers, a bit is in either a one or zero state. In a quantum
computer, through linear superposition, a quantum bit can be in
both states, essentially simultaneously. Thus, computations consisting
of trail evaluations of binary patterns can take place simultaneously
in exponential time. The probability of obtaining a correct result is
increased through a phenomenon called constructive interference of
light while the probability of obtaining an incorrect result is decreased
through destructive interference. Answer a describes optical computing
that is effective in applying Fourier and other transformations to data to
perform high-speed computations. Light representing large volumes of

data passing through properly shaped physical objects can be subjected
to mathematical transformations and recombined to provide the appropriate
results. However, this mode of computation is not defined as
quantum computing. Answers c and d are diversionary answers that
do not describe quantum computing.