Abstract:
In this thesis, I have given a brief overview to the answers of two central
questions in quantum computation. How much information can be encoded
in quantum systems, and how efficiently can this information be
extracted. Manipulation of quantum information through manipulating
quantum states is relatively well studied topic. This is usually achieved
by unitary transformations. In this thesis, after giving a brief overview
of fundamentals of quantum computation, basic quantum information
theory is briefly discussed. After that, the main question about how to
estimate a quantum state has been looked into more carefully. Given a
finite ensemble of a particular quantum state, say N copies, firstly a score is
defined to measure how accurately the state is estimated. Then a bound for
this score is calculate and is shown to be N+1
N+2 , for a finite ensemble. In my
work, with estimated state, I have tried to define quantum measurement
in a more general fashion.