Optical Control of Quantum States in Semiconductor Nanostructures

Lead Research Organisation: University of Sheffield
Department Name: Physics and Astronomy


The interactions between light and matter in the solid state underpin a wide variety of important areas of science and technology, ranging from commercially available devices such as light emitting diodes and lasers, to very futuristic topics such as logic gates based on quantum mechanical principles, writing and reading of single spins, storage of single photons, and new types of coupled matter-photon particles exhibiting exotic properties such as condensation into a coherent state. However, it is only within approximately the last five years that the technologies have emerged to accurately prepare and control the properties of electrons in fully confined structures, and to fabricate small volume high performance nano-cavities to control the properties of photons, and thus to access many of the above very forward-looking opportunities.This leads to the subject area of the present proposal: we aim to control the quantum states of electrons and photons and of their mutual interactions to produce new advances in quantum information science, quantum optics and interacting coherent systems. This will be achieved by a highly interactive programme comprising the essential component parts of advanced experimentation and theory, and well developed crystal growth and device technology, both within our own laboratories and with collaborators within the UK and Europe.The research we propose is closely interlinked, and focuses into four related areas, all involving similar samples, experimental techniques and theoretical concepts, in the areas of ultrafast quantum control, nano-magnetic systems, entanglement of remote quantum systems, and the condensed high density state which arises in specially designed optical cavities. It is expected to result in major advances towards a number of long-term goals, for example: the exploitation of the long coherence time of electron spins for quantum information processing, quantum logic in semiconductor systems, the development of scalable qubit systems based either on excitons or photons, and superfluidity and quantum oscillations in designer-controlled interacting systems.Support is requested via Programme Grant funding of the Physics Programme of EPSRC. Such funding is specifically designed to permit the establishment of coherent activities which are able to compete successfully on the international scale, and has been critical to our recent successes.


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Description Major achievements were achieved in the control of the interactions between light and matter in semiconductor nanostructures. Principal advances include:

1. Ultrafast optical control of phase of single spins was realised.

2. Dephasing mechanisms of excitonic qubits in quantum dots were understood.

3. Hole-nuclear hyperfine interactions in quantum dots were determined, and their strength relative to those for electrons were revealed.

4. Excitonic dressed states and their ultrafast evolution in quantum dots were demonstrated.

7. The mode structure of photonic crystal cavities was understood both experimentally and theoretically.

8. Dephasing mechanisms in the polariton condensate were revealed.

9. Spontaneous and imprinted vortices in the polariton optical parametric oscillator were revealed and investigated.

11. Tunable polariton lattices were demonstrated.

12. Observe spin multistability and related spatial patterns in polariton condensates were revealed and modeled theoretically. 13. New quantum optics phenomena observed in wave guide structures.
Exploitation Route Through the UK Quantum Technology Programme.
Sectors Digital/Communication/Information Technologies (including Software),Electronics