The Importance Of a 'Sexy' Title

General Interests

Ok so I started by doing plenty of reading, and specifically developed a general background for the area from John Preskill's lecture notes along with the always useful (and constantly cited!) Quantum Computation adn Quantum Information book by Micheal Nielsen and Isaac Chuang, if you have any interest in the field and don't know something check here first! Once I had a feel for the area Mauro pointed me at a paper published in 2003 by Kei, Munro etc in which they parameterised the class of states known as Maximally Entangled Mixed States (MEMS). They really are very interesting since they represent the boundary of physically realisable states, the relevance is further enhanced when you consider that they are (at least in the 2 qubit sense) the mixed state equivalant of the maximally entangled Bell state. From here I first started doing a few 'little' calculations to see how different forms of quantum noise affect them.

Kylie Minogue

Now my work is broadly centered around area's concerning quantifying, discriminating, and testing the robustness of entanglement in various n-body systems. My first paper deals with a scheme to approach the two qubit MEMS boundary through what is a relatively experimentally friendly set-up. In a nut-shell we take two qubits, put them in an imperfect cavity and then inject a field into the cavity. Once we let the field 'leak out', what we have done is taken what have been two initially uncorrelated systems and via the field allow them to interect and become entangled. There where some nice results to come out of it. You can get it here and its published in Phys. Rev. A

Scarlett Johansson

I also dabbled with looking at entanglement detection of symmetric Dicke states in the presence of noise. This was some nice work done not only with Mauro, but also with Dr. Mark Tame (another great guy in our group!). In this paper we look at a range of methods to determine if a state is exhibiting genuine multipartite entanglement. In particular we study how resiliant collective spin based entanglement witnesses and the more common fidelity based entanglement witnesses are to noise, as well as decoherence on the correlaton function and state discrimination via characteristic operators. It's a nice paper particularly because of the experimental relevance. Its avaliable from here, and it's published in New Journal of Physics.

Angelina Jolie

With an upcoming special issue of International Journal of Quantum Information centering on Distributed Entanglement, we thought it would be nice to submit something. We got to working on a teleportation protocol using maximally entangled mixed states (MEMS) as the quantum channels to teleport bipartite entanglement. This work ended up being even more interesting than either of us expected. For the interested parties out there, if you measure entanglement through negativity then MEMS correspond exactly to Werner states. Teleporting bipartite entanglement using Werner states was already considered by Prof Myungshik Kim and Dr. J Lee back in 2000 (before it was even known that these states where MEMS). One would expect since our analysis was simply using a different entanglement measure which necessarily meant a different parameterisation the qualitative features should be the same. Not so! This was a nice paper to work on. You can get it here with the proper special edition reference coming soon I hope!

Jennifer Love Hewitt

I've also been starting on a little work with a group based in the Univeristy of Palermo. Here I'm working with Giuseppe Gennaro and Prof. Massimo Palma (formidably intelligent men!). As of July 1st I've just finished the first draft of the paper hopefully not long before the proper thing is avaliable! The basis of this work has been to examine entanglement properties when we have increasingly sized registers of qubits and an ancillary qubit interacting with the registers via various Heisenberg type interactions. We modeled an initial evolution of the registers using random unitary matrices. Again some nice features appear. First using this random matrix approach we can consider the registers being affected by thermal decoherence. Then one may assume entanglement may not be readily generated. We find (over a statistical average) that we can genreate relativily large amounts of entanglement. More shockingly the structure of the tripartite entanglement shared between the interacting quibts can be manipulated simply thorugh tuning the interaction and number of qubits in the registers. As soon as we're finished the paper will be up on the archive.

Keira Knightley

A number of months ago I had a chance to work on some "unfinished" work of Mauro's (in collaboration with Myungshik and Prof Sugato Bose). This work was done about 2 years ago but never quite finished. I did a few calculations and helped finished it all of and tighten it all up. The work is really interesting. We show that if you have a qubit immersed in a decohering environment and this qubit is completely inaccessable, by sinply coupling this qubit to a "clean" qubit through a suitable interaction we are able to generate entanglement between the two but also by doing this we can infer pretty much everything about the inaccessable environment the qubit is immersed in! More interestingly even when the entanglement between the two qubits decays we can still infer everything simply through existing classical correlations. Its a really nice paper. Hopefully it will be on the archive soon.

Other Stuff

All the while I also have a firm interest in trying to extend the known class of MEMS from just the two qubit setting to three qubits. This is a rather large task, with many hurdles, but with a little luck (and an ungodly amount of work) I'm hoping we can get some understanding of them. This is slowly progressing (I've got a few promising plots!) but still a lot to go!

So if your reading this and have some suggestions/your interested in hearing more (or even trying a possible collaboration!) please drop me a line.

Presentations