position:

deadline:

description:

D.Phil. studentships in QIP

We anticipate that we will be able to offer one or more doctoral studentships in the area of quantum information processing. Our group has broad interests, ranging from detailed modelling of semiconductor structures through more abstract ideas related to designs for quantum computer architectures and extending to fundamental questions about the nature of quantum information and measurement. At the time of writing the following are active projects:

i) Measurement based quantum computing. One can regard quantum entanglement as the fundamental resource needed in order to execute quantum algorithms. Certain kinds of entangled states exist which are universal resources, in the sense that any quantum algorithm can be performed simply by performing a prescribed series of quantum measurements. Moreover, even the entangled state itself can by created by making measurements. These insights have led to many new possible implementations of quantum computers, for example: one that uses only photons, one exploiting crossed atomic beams and others based on optical measurements on colour centres in diamond.

Specific topics are: first principles physics of measurement, implementation of error correction or avoidance and entanglement creation by measurement.

ii) Solid state nanostructures and quantum computing. We are looking at how certain solid state nanocrystals (such as quantum dots, carbon molecular arrays or colloidal crystals) can be used to implement quantum gate operations. We have developed methods for coherent quantum control of systems with a range of Hamiltonians. We are also interested in modelling decoherence, which is caused by the interaction of a system with its environment, which employs in particular, the Markovian master equation description of open quantum systems.

iii) Spin chains. One of the most important questions in quantum information processing is how we might transmit information from one computer to another. We have been looking at at this might be done using one (or higher) dimensional arrays of interacting spins (or similar quantum two level systems). An important theme is to achieve as much as possible with minimal external control --- in other words, to exploit the 'natural' dynamics of the spin system as completely as possible. For example, recent work has involved new realisations of the "quantum mirror" phenomenon, whereby a set of quantum states lying along a spin chain will delocalise, due to the spin-spin interactions, but then "revive" at the mirror site at the other end of the chain. More generally, any scheme offering _global control_, i.e. control of a network of spins without the need to target individual elements, if of interest to our group.

One of the listed supervisors (Pieter Kok) has recently taken up a lectureship at Sheffield and he will be one of several collaborators on these projects. Others will include the quantum dot experimental group of Prof Dirk Bouwmeester (UCSB, California), Dr Tom Stace (University of Queensland), Dr Dan Browne (University of Oxford) and Dr Tim Spiller (Hewlett Packard Labs, Bristol). Currently no specific funding is in place; however, a number of funding routes exist and we would be happy to advise strong students about how to explore these.