FY2014 Student Project

We usually have a number of projects available and details on some of the current opportunities can be found below. If any of these interest you, please get in touch for more details. Please also note that support for an internship can be obtained through the OIST Graduate School Research Internships.

Matter-wave STIRAP in multiple dimensions

Lasers cooling has allowed to slow atoms to temperatures just a few microkelvins above the absolute zero and confine them in microscopical traps. Matter-wave STIRAP (MWS) is a quantum-mechanical technique that allows to control and engineer the external degrees of freedom of such ultracold atoms and, for example, transport them coherently betwen different potential wells. While the application of MWS to one-dimensional systems has been extensively studied theoretically, its use in multi-dimensional configurations has only recently started to be explored and was shown to, for example, allow the creation of  angular momentum carrying states.

In this project we plan to study the application of the MWS technique to two-dimensional configurations by numerically integrating Schrödinger's equation. Our aim will be to achieve atom transport in a simplified system where there is only one moving trap or in  geometrical configurations that will allow for the efficient preparation of quantum states that are of interest in quantum information processing.

Vortex dynamics in quasi-2D Bose-Einstein condensates

Bose-Einstein condensates offer a means to study and understand many fundamental physical phenomena, among them the appearance and properties of superfluids and quantised vortices. Using the degrees of freedom offered by the presence of an external trapping potential allows to change the superfluid dynamics in a controlled way and can therefore be used to study its properties over a wide range of settings.  

This project will use the Fourier Transform/Split-Step algorithm to simulate a system carrying vorticity  on our HPC and/or GPU computing (CUDA) hardware. The goal will be to obtain information from the Wigner distribution of the wave function and infer dynamical behaviour for a condensate with a low number of vortices. Insight into the phase-space behaviour for a variety of condensate parameters should allow for a deeper investigation into condensate dynamics.

Extension and optimisation of GPUE Gross-Pitaevskii CUDA-based Bose-Einstein condensate codebase

Bose-Einstein condensates are readily modelled using the well known mean-field Gross-Pitaevskii equation. Due to the required resolutions and timescales, such systems require significant computational resources to solve. The use of graphics processing units (GPU) to accelerate such simulations has become an area of much interest in recent times, owing to their inherently ease in handling parallelism.

The bulk of this project will involve further development of the CUDA-based GPUE codebase to enable multiple GPU’s to perform simulations on an individual dataset. Through use of advanced CUDA and C/C++ language, an arbitrarily large dataset may be examined using multiple GPU’s to enable the simulations. Optimisation of the codebase to achieve the highest throughput possible will be essential to the success of this project, and will enable more advanced condensate systems to be investigated.

Bose-Einstein condensates with spin-orbit coupling

Spin-orbit coupling, relating to a particle’s charge degrees of freedom, plays an important role in many physical phenomena. In ultra-cold atomic gases made of neutral atoms system, it must be generated synthetically, and experimental progress towards engineering spin-orbit coupling in ultra-cold quantum gases has been fast and successful in recent years.  Besides the motivation to stimulate spin-orbit coupled physics in solid state systems, the interest to investigate spin-orbit coupled atomic gases has its own right.  For example, the interplay between spin-orbit coupling and atomic interactions gives arise to many interesting phases that are currently attracting a lot of attention.

The aim of this project is to study the possibility to generate spin-polarized superfluid using spatial inhomogeneous spin-orbit coupling in a Bose-Einstein condensate (BEC).   The relevant physics is the dynamics of two components BEC.  Inhomogeneous spin-orbit coupling introduces super flow imbalance between two components. Once such spin-polarized superfluid is generated, what is its stability property, which relates to atomic interactions?

Quantum turbulence in BECs

Atomic Bose-Einstein condensates are an ideal system in which to study quantum turbulence, a dynamical tangle of reconnecting quantum vortices. BECs are experimentally accessible and can be finely tuned, promising great control over aspects such as single-vortex dynamics to well resolved vortex imaging. There are a couple of projects available to investigate under this topic:  

One project is to investigate how to minimise acoustic energy, or sound, produced in forced quantum turbulent systems, through two or three dimensional numerical simulations of the Gross-Pitaevskii equation. In other words, you will try to answer the question: Can the condensate trap be designed in such a way as to mimic an anechoic chamber for a BEC? 

An alternative project will be to look at the interplay of chaos and turbulence by studying vortex dynamics in Bose-Einstein condensates. This will require integrating the time-dependent Gross-Pitaevskii equation. 

Characterizing chaotic dynamics for a four mode BEC in a double well

A Bose-Einstein Condensate (BEC) is a coherent state of matter in which many ultra-cold bosonic particles share the same wavefunction. In a double well potential, there are usually two states (or modes) possible, corresponding to atoms in the left or the right well. Depending on the height of the barrier and interaction strength between atoms, the atoms can be allowed to tunnel from one well to the other. In a mean field theory, each mode can be described with a classical coordinate system.

In this project, we want to investigate the dynamics of the system if two additional excited modes are added to the system. More specifically, using existing classical Hamiltonian and equations of motion, we want to highlight and characterize the presence of chaotic dynamics in the system depending on initial conditions and physical parameters.

Quantum Phase Transitions around a Tapered Nanofiber.

Tapered optical nanofibers, which are just a few hundred nanometers in diameter, offer a wealth of applications for trapping, sensing and probing atoms.  Such tapered fibers are created by stretching a single mode fiber over a hot flame until its diameter is reduced to a size smaller than the propagating radiation wavelength. Under these conditions most of the power of the field propagating in the fibre is sitting outside the fiber surface. This evanescent light field around a nanofiber can be used to trap and guide atoms. The geometry of the resulting trapping configurations can be tailored by adjusting the parameters of the propagating light field or also by introducing two propagating fields at once. Trapping geometries can be prepared in the form of a double helix wrapped around the fibre surface, or even in the form of a regularly spaced lattice trap.

Ultracold neutral bosonic atoms can be stored in magnetic traps and cooled down to very low temperatures (of just a few micro Kelvin) where they condense into a superfluid below a critical temperature.  The transition can be probed by tuning the system's interaction parameters. The importance of the interactions can be drastically enhanced by subjecting the atomic gas to a periodic lattice potential. In a regular optical lattice formed by the interference of counter propagating laser fields the celebrated Mott-insulator superfluid transition has been observed. We want to investigate the possibility of observing such a quantum phase transition in the vicinity of the fibre.