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Journal of Optics B: Quantum and Semiclassical Optics has published five PhD tutorials in the last three years. In 2000, three of the top 20 papers (by full text download via the journal homepage) were PhD tutorials.

Previous tutorials have included:

Guidoni L and Verkerk P 1999 Optical lattices: cold atoms ordered by light vol 1 R23-R45 van Dorsselaer F E and Nienhuis G 2000 Quantum trajectories vol 2 R25-R33 Jedrkiewicz O and Loudon R 2000 Atomic dynamics in microcavities: absorption spectra by Green function method vol 2 R47-R60 Sivakumar S 2000 Studies on nonlinear coherent states vol 2 R61-R75 Sackett C A and Hulet R G 2001 Dynamics of Bose-Einstein condensation in a gas with attractive interactions vol 3 R1-R28

PhD tutorial competition

The journal wishes to attract more high quality tutorials and we are launching a competition for the best PhD tutorial. Tutorials are invited from any subject within the journal's remit (optical phenomena in which the field and/or matter need to be described by quantum theory). A committee, selected from the Editorial Board, will be asked to judge the competition and will base its decision on the referees' comments. A prize fund of £500 will be distributed to the best papers. All PhD tutorials that receive favourable reviews will be published in the journal throughout the year (between 1 September 2001 and 1 September 2002). The winners will be announced by the beginning of 2003.

Guidelines for writing a PhD tutorial

A tutorial should generally be based on the introduction of a thesis and may be up to 30 pages in length (including figures). The originality of the paper should be: a systematic derivation from first principles of the working equations for a problem or field; or a critical assessment of the experimental status of the subject and a comprehensive bibliography.

The PhD tutorial will be authored by the student completing the thesis and the thesis advisor. Topic, breadth, bibliography and writing style will be considered in the judging.

Submission information

All tutorials will be refereed according to the high standards of the journal and authors will receive 25 free offprints of their published paper. There are no page charges. Manuscripts should be prepared following the general guidelines for authors published in the journal. Full instructions can be found at http://www.iop.org/Journals/nfa/index.html. Please include a covering letter stating that the submission is to be considered for the PhD tutorial competition.

Manuscripts should be submitted to the Publisher by the 1 September 2002, although authors are strongly encouraged to submit their work as soon as possible.

A microscopic many-body theory for the optical and electronic properties of semiconductors is reviewed with an emphasis on the role of correlation effects. At the semiclassical level, the semiconductor Bloch equations include many-body effects via bandgap and field renormalization as well as correlation contributions representing two electron-hole pair amplitudes, excitonic populations, and coupled interband and intraband coherences. These Coulomb interaction induced carrier correlations lead to characteristic signatures in nonlinear semiconductor spectroscopy. At the fully quantum mechanical level the dominant light-matter correlations are described by coupled semiconductor Bloch and luminescence equations. Excitonic emission properties of quantum well and microcavity systems are discussed, including effects such as coherent signatures in the secondary emission and coherent control of the emitted light.

We propose a quantum teleportation scheme in which a quantum state is teleported from the sending station (Alice) to either of two receiving stations (Bob1, Bob2). In this scheme, two pairs of EPR beams with identical frequency and constant phase relation are used to produce two pairs of conditional entangled beams by composing their modes on two beamsplitters. One output of a beamsplitter is sent to Alice and the two outputs of the other beamsplitter are sent to Bob1 and Bob2. Which receiving station actually receives the teleported state can be decided by correlating the in-phase or out-of-phase quadrature components of two two-mode squeezed vacuum states. The switch system manipulated by squeezed state light might be developed as a practical quantum switch device for the communication and teleportation of quantum information.

A scheme is proposed for generating motional pair coherent states of an ion in a two-dimensional anisotropic trap. In the scheme the ion is excited by two laser beams in the x-y plane. Under certain conditions, the system finally reaches the steady state given by the product of the ground electronic state with the motional pair coherent state. The scheme can be generalized to prepare pair cat states and two-mode SU(1,1) intelligent states in a two-dimensional anisotropic trap.

The real and imaginary negative binomial states formed by a superposition of the negative binomial states are introduced. The sub-Poissonian statistics, Wigner function and squeezing properties of the real and imaginary states are studied in detail. The oscillatory character of the photon distribution due to the quantum interference between the two components is shown. Moreover, we find that these states are real and imaginary nonlinear Schrödinger cat states and give the corresponding ladder operator formalisms. We also discuss how to generate these general real quantum superposition states based on the intensity-dependent Jaynes-Cummings model.

We study the entanglement between the 2D vibrational motion and two ground state hyperfine levels of a trapped ion. Under particular conditions this entanglement depends on the parity of the total initial vibrational quanta. We study the robustness of this quantum coherence effect with respect to the presence of non-dissipative sources of decoherence, and of an imperfect initial state preparation.

We show that, for a given critical power, drastic changes in the stability of light beams take place in cubic-quintic nonlinear optical materials. High-power nodeless beams illuminating an appropriate phase mask yield to vortex states that propagate through long distances without breaking. Our predictions can be easily tested in the frame of current experiments and provide interesting questions about the physics of cubic-quintic nonlinear optical media.

We show that manipulation and selection of optical patterns is possible by detuning the frequency of one of the two waves in counterpropagating photorefractive two-wave mixing with a feedback mirror. An analytical expression for the onset of modulational instability is derived for the general case of an arbitrary complex coupling constant, including a possible frequency shift of the generated sidebands. The influence of frequency detuning of the pump beams on the spatial scale of the resulting pattern and on the threshold value of the photorefractive coupling strength for modulational instability is investigated. The spatial scale and the frequency detuning of the generated sidebands were measured in an experiment using a photorefractive KNbO₃ crystal. Comparison of theory and experiment show agreement for positive frequency detuning of the pump beams. For negative detuning we observe clamping of the spatial scale and no frequency shift of the sidebands. Possible explanations of this deviation between analytical results and experiment are discussed.

We propose a scheme to drive the centre-of-mass vibrational motion of two trapped ions to an arbitrary finite superposition of Fock states from the vacuum state. In order to generate a superposition of N Fock states we need N operations. The scheme does not require differential laser addressing of individual ions.

We propose a scheme for generating superpositions of coherent states for both the centre-of-mass and relative vibrational modes of two trapped ions. In the proposed scheme two trapped ions are driven by two laser beams dispersively tuned to the first lower- and upper-vibrational sideband transitions, respectively. Under certain conditions, the measurement of the internal states leaves one vibrational mode in a superposition of two coherent states. Entangled coherent states for these two vibrational modes can also be generated. The scheme can be used to measure the Wigner function of one vibrational mode given that the other mode is initially in the vacuum state.

We address the problem of the optimal quantum estimation of the coupling parameter of a bilinear interaction, such as the transmittivity of a beamsplitter or the internal phase-shift of an interferometer. The optimal measurement scheme confirms Heisenberg scaling of precision versus the total energy as an unsurpassable bound, but with a largely reduced multiplicative constant.

The possibility of producing entangled superpositions of strong coherent states is discussed. A recent proposal by Howell and Yeazell (2000 Phys. Rev. A 62 012102) of a device that entangles two strong coherent states is modified. It is shown that the modified scheme can generate non-classical states that violate Bell inequality. Moreover, a detailed analysis of the effect of losses and decoherence on the degree of entanglement is accomplished. It reveals the high sensitivity of the device to any disturbances and the fragility of generated states.

Correlated photons have been used in quantum optics for the generation of squeezed light, demonstration of quantum interference effects, quantum cryptography, Einstein-Podolsky-Rosen experiments and most recently, quantum teleportation. Usually, they are generated using χ⁽²⁾ parametric processes to take advantage of large χ⁽²⁾ nonlinearities and to wavelength separate the correlated photons from the pump photons. Here, we examine the generation of correlated photons using χ⁽³⁾ parametric processes in optical fibres. We show that using such processes provides a simple and inexpensive correlated photon source readily compatible with communications technologies.