David Luong of the Department of Physics and Astronomy will be defending his thesis:
The Practical Realization of Quantum Repeaters: An Exploration
David is supervised by Professor Norbert Lütkenhaus.
The behavior of conventional transistors derives from large numbers of acceptor and donor impurities that promote carriers into the valence and conduction bands. More recently, nano-electronic devices based on the bound states of individual dopant impurities in silicon have received considerable attention for quantum computation, due to the long spin coherence times of dopants in silicon. This invariably requires control over dopant wavefunctions and the interactions between individual dopants [1].
Juan Miguel Arrazola of the Department of Physics and Astronomy will be defending his thesis:
Practical Quantum Communication
Juan Miguel is supervised by Professor Norbert Lütkenhaus.
The act of observation has profound consequences on a quantum system. I will describe our experimental demonstration of a Heisenberg microscope based on nondestructive imaging of a lattice gas. We show that the act of imaging these atoms induces their localization - a manifestation of the quantum Zeno effect.
We study the word problem for the free skew field of non-commutative rational functions. We prove that an existing algorithm due to Gurvits is actually a deterministic polynomial time algorithm for this problem (over the rationals). Our analysis is simple, providing explicit bounds on the "capacity'' measure of totally positive operators introduced by Gurvits.
We will review known results about order isomorphisms of C*-algebras,
and will describe some applications to complete positivity of maps and
a generalization of the Choi matrix. (This is joint work with Vern Paulsen.)
Then we will describe some applications to quantum information theory.
A classical current in a conductor radiates a classical electromagnetic field. We explore some properties of the field radiated by a conductor when electron transport must be described by quantum mechanics, i.e. when the electron current becomes quantum itself.
The dihedral coset problem (DCP) is an important open problem in quantum algorithms and has been studied since the early days of quantum computing. This problem attracts attention even from experts in cryptography due to its application to the lattice-based cryptosystems. It has been shown by Oded Regev in 2005 that the DCP has deep connections to the unique shortest vector problem and the random subset sum problem.
We report a quantum hacking strategy on a Continuous-Variable (CV) Quantum Key Distribution (QKD) system by inserting an external light. In the implementations of CV QKD systems, transmitting openly local oscillator pulses is a potential vulnerability for an eavesdropper to launch side channel attacks. In this work, other than targeting on local oscillator, we concern two imperfections in a balanced homodyne detector used in CV QKD system: the imbalance in the beam splitter and the finite linear detection limit.
The first part of the talk presents recent progress in the search for condensed matter systems hosting Majorana bound state in semiconductor-superconductor nanowire-based heterostructures. In the second part a proposal for the next steps towards manipulation of quantum information stored in topological qubits is presented.