This thesis presents a study of the structure of bipartite quantum states. In the first part, the representation theory of the unitary and symmetric groups is used to analyse the spectra of quantum states. In particular, it is shown how to derive a one-to-one relation between the spectra of a bipartite quantum state and its reduced states, and the Kronecker coefficients of the symmetric group. In the second part, the focus lies on the entanglement of bipartite quantum states. Drawing on an analogy between entanglement distillation and secret-key agreement in classical cryptography, a new entanglement measure, `squashed entanglement', is introduced.
- Pub Date:
- April 2006
- Quantum Physics;
- Quantum Physics
- PhD thesis, February 2006, University of Cambridge. Part I contains results from quant-ph/0409016 and quant-ph/0511029, and analyses Horn's problem in this context. Part II reviews entanglement measures, presents results from quant-ph/0308088 and quant-ph/0501090, and provides new material on entanglement measures, information-gain versus disturbance tradeoffs and cheat sensitive quantum string commitment