Last update: T_KCHFO (14.04.2010)
Theory of quantum computation is a relatively young field, however, its roots can already be found in the pioneering
years of quantum mechanics and classical information theory. First the modern quantum information theory satisfactorily
explained for example the Einstein-Podolsky-Rosen paradox or the Maxwell daemon. A spectacular success of this
theory was the discovery of a polynomial quantum algorithm for number factoring by Shor, on the experimental field an
equally important achievement was the realization of quantum teleportation. Entirely secure quantum cryptography,
based on the fact that any eavesdropping on a transmitted quantum state is in fact a measurement and perturbes the
state, is presently even commercially available and employed in military applications. Somewhat less medialized is the
recent success on the field of quantum computations of many-body systems. The potential benefit of quantum
computers for accurate calculations of many particle systems, which exhibit an exponential computational demands in
the number of particles on classical computers, has been first realized by Feynman in 1982. In spring 2010 the first
computation of the hydrogen molecule in minimal basis set has been published in Nature. In spite of the present limitation
of quantum computers to a few qubits it is possible that a breakthrough in their scalability could come soon and they
would thus become the technology of the 21st century.
Students interested in this lecture should master knowledge of quantum mechanics at least at the level of the course NOFY027 (Introduction to quantum mechanics).
The lecture is based partly on a selection of material from two textbooks (see Literature), partly on
primary literature.
Selection of topics:
- Reversible classical computations
- Computational complexity
- Quantum bit
- Measurements in quantum mechanics
- Entanglement, EPR and Bell inequalities
- Quantum cryptography and teleportation
- Quantum gates and circuits
- Quantum Fourier transform
- Shor's factoring algorithm
- Quantum phase estimation algorithm and its iterative version
- Quantum computations of many-electron systems
- Quantum noise and error corrections codes
- Alternatives of the gate model - adiabatic quantum computers