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Welcome to GPUE, the fastest zero temperature BEC routines in the land (the last time we checked).
Runs on CUDA 7.0 (C++11 functionality needed) on both Linux and Mac OS X (Nvidia GPU only). We have not tested on Windows. Other requirements are Python 2.6+ (though PyPy is MUCH faster), Numpy, Scipy, Matplotlib, Mencoder.
To build, first check the predefined paths in the Makefile (CUDA lib/lib64, bin, include, etc).
Configuring the simulation parameters is as easy as editing the bin/run_params.conf file, and entering them as specified. Each new line will represent another simulation, with the maximum number of simultaneous simulations to be given in run.sh.
To run the simulations: chmod +x ./run.sh; ./run.sh
If the image generation fails, this can be rectified manually by editing the file py/vis.py, and selecting the appropriate operation. Not all Python code may currently not behave as expected, due to the switch over to vortex tracking entirely in C++.
Many routines are also being converted from C host-code to C++11 host-code, so if there is any strange behaviour then please let me know. Bug reports are always welcome, as well as comments, improvements, cake, free-dinners and cold weather.
If you enjoy/use/learn from this code, please give me a citation, as it took a long time to develop, and I'd appreciate it greatly! A nice email would suffice too :)
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This software is a CUDA-enabled non-linear Schrodinger (Gross-Pitaevskii) equation solver. The primary use of this code was for my research on rapidly rotating Bose-Einstein condensates. Due to the complexity and timescales needed to simulate such system, it was essential to write some accelerated code to understand the behaviour of such systems. If you would like to know more, check my Google scholar profile https://scholar.google.com/citations?user=s-6jND0AAAAJ&hl=en which will update as we finish some papers.
The premise is the following: We want to simulate how a Bose-Einstein condensate (BEC) behaves in a trap. The trap is parabolic (harmonic), and for the lowest energy state of the system (ground-state) the BEC will want to sit about the centre. Due to the interaction between the particles it will occupy more space than a standard Schrodinger equation, which has zero interactions. As a result of these interactions many interesting things happen.
The main purpose of the code is to investigate the behaviour of quantum vortices (think really small tornadoes). Instead of having a continuous range of angular momentum values, the condensate can only accept angular momentum in quantised predefined units.
The most interesting fact is that instead of getting bigger and bigger with faster rotation (as a tornado would), these vortices only allow themselves to enter with a singular unit of angular momentum (think 100x 1 unit vortices instead of 1x 100 unit vortex). This gives us a nice well arranged lattice if performed correctly. It is this lattice that we have been researching (read as: playing with). However, this code can be used in any trapping geometry, rotation, etc. that you wish to use. Bear in mind, we have developed this for a 2D system only. Extensions to 3D are currently in the works, and are in the beta branch lead by the amazing James Schloss (leois). When completed, these will be merged into master.
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Well, first you need to look at the run_params.conf file, and give it some necessary parameters to generate your favourite condensate.
As an example ./gpue -x 256 -y 256 -T 1e-3 -t 1e-3 -n 1e5 -g 1e3 -e 1e3 -p 1 -r 0 -w 0.3 -o 10 -d 0 -l 1 -s 1 -i 1.0 -P 0.0 -G 1.0 -L 0 -X 1 -Y 1 -k 0 -O 0.0 -W 1 -U 0 -V 0 -S 0.0
As an example, here are some simulations performed with the code: https://www.youtube.com/playlist?list=PLiRboSbbz10s6cXxvYLFOn3QbmQpdtQVd
The above parameters will be better explained when the papers have been published (which is only fair). Comments will be added for relevant sections too to allow for their use.
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############################################################################### I would like this tool to be a suite for 1D, 2D and 3D simulations of both Schrodinger and non-linear Schrodinger systems.
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############################################################################### A citation would be nice :) Feel free to cite as:
Lee James O'Riordan et al., GPUE: Phasegineering release, Zenodo. (2016) \url{https://github.com/mlxd/GPUE} DOI:10.5281/zenodo.57968
Otherwise, an email with a message, comments, or anything is appreciated. I'm curious as to who is using this, so regardless of what you do with it, feel free to get in touch.
If you would like to help, I am always looking for some additional improvements. There is a lot remaining to be done, but many hands make light work, after all.
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############################################################################### We are greatly thankful to the support provided by Okinawa Institute of Science and Technology Graduate University, without whom this research code would be a fraction of what it currently has become. To the various people who have contributed in ideas and parts to this project, in no particular order: Albert Benseney Cases, who assisted with the multivortex vortex tracking and various discussions; Angela White, who assisted with calculating the spectra and with a variety of physics discussions; Tadhg Morgan, for initial discussions and works with simulating cold atoms; Thomas Busch, for guidance over the many areas of physics this code has touched upon.