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The HEPQPR.Qallse project encodes the HEP (ATLAS) pattern recognition problem into a QUBO and solves it using a D-Wave or other classical QUBO libraries (qbsolv, neal). Master's project (2019).



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The HEPQPR.Qallse project encodes the HEP (ATLAS) pattern recognition problem into a QUBO and solves it using a D-Wave or other classical QUBO libraries (qbsolv, neal).

The algorithm acts as a doublet classifier: the input is a large collection of potential doublets, the output is a subset of those doublets that are believed to form true track candidates.

Contribution and reuse

This code is under an Apache 2.0 license, so you are free to do pretty much everything you want with it ;).

However, I put a lot of work and time on it, so it is easy to use/read/fork/understand. If you happen to be interested, I would really appreciate if you could add a star to the project and use the Github fork mechanism (and mention the repo/the author in case you present your results somewhere).

I am available for any question (email or Github issue is fine) and would be glad to hear about your ideas and improvements ! 🐙🐙



Algorithm overview

algorithm overview

Current models

Different versions of the model building (i.e. QUBO generation) exist. They are organised into a class hierarchy starting at the abstract class hepqpr.qallse.QallseBase:

  • .qallse.Qallse: basic implementation, using constant bias weights.
  • .qallse_mp.QallseMp: adds a filtering step during triplets generation, which greatly limits the size of the QUBO;
  • .qallse_d0.QallseD0: adds variable bias weights in the QUBO, based on the impact parameters d0 and z0.


The datasets used for benchmarks can be recreated by executing the scripts/ script. All you need is to have the TrackML training set ("").

All benchmarks have initially been made using QallseMp (initial model). QallseD0 is an improvement to limit the number of fakes, but relies on skewed physics assumptions. It has also been benchmarked (less thoroughly).

The raw results of all benchmarks are available here:

Performance overview


  • model building is kind of slow: expect up to 1 hour for the biggest benchmark dataset;
  • QUBO solving using qbsolv can be slow, especially using a D-Wave: expect up to 30 minutes in simulation (unbounded using a D-Wave, up to 5 hours in our experience)
  • QUBO solving using neal is nearly instantaneous: up to 14 seconds.


Physics performance overview

Setup and usage


Clone this repo, create a virtualenv and run

# clone
git clone <this repo>
cd <dir>

# create and activate virtualenv
python3 -m venv my_virtualenv
source ./my_virtualenv/bin/activate

# install
cd src
python install # or python develop for development


# create a small dataset of 1% of a full event (be verbose)
create_dataset -n 0.01 -p mini1 -v

# run the algorithm
qallse -i mini1/event000001000-hits.csv quickstart

Commandline tools

The main commandline scripts are:

  • create_dataset: to create datasets from TrackML events.
  • qallse: run the algorithm.

Other tools are:

  • run_seeding: generate the initial doublets, you only need it if you call create_dataset with the --no-doublets option.
  • parse_qbsolv: this parses a qbsolv logfile (with verbosity>=3) and generates a plot showing the energy of the solution after each main loop.
  • filter_doublets: this can be used to remove doublets with too many holes from the input doublets.

Each tool comes with a -h or --help option.

Typical example:

> mkdir /tmp/mini

# generate a dataset of 5% in /tmp/mini/ds05
> create_dataset -o /tmp/mini -p ds05 -n 0.05
Dataset written in /tmp/mini/ds05/event000001000* (seed=376778465, num. tracks=409)

# build the model
> qallse -i /tmp/mini/ds05/event000001000-hits.csv -o /tmp/mini build
INPUT -- precision (%): 0.8610, recall (%): 99.5885, missing: 1
2019-01-29T09:54:05.691 [hepqpr.qallse.qallse_d0 INFO ] created 15341 doublets.
2019-01-29T09:54:06.995 [hepqpr.qallse.qallse_d0 INFO ] created 3160 triplets.
2019-01-29T09:54:07.022 [hepqpr.qallse.qallse_d0 INFO ] created 686 quadruplets.
2019-01-29T09:54:07.022 [hepqpr.qallse.qallse_d0 INFO ] Model built in 3.12s. doublets: 15341/0, triplets: 3160/0, quadruplets: 686
2019-01-29T09:54:07.030 [hepqpr.qallse.qallse_d0 INFO ] MaxPath done in 0.02s. doublets: 544, triplets: 628, quadruplets: 638 (dropped 48)
2019-01-29T09:54:07.073 [hepqpr.qallse.qallse_d0 INFO ] Qubo generated in 0.07s. Size: 2877. Vars: 628, excl. couplers: 1611, incl. couplers: 638
Wrote qubo to /tmp/mini/qubo.pickle

# solve using neal
> qallse -i /tmp/mini/ds05/event000001000-hits.csv -o /tmp/mini neal
2019-01-29T09:56:51.207 [hepqpr.qallse.cli.func INFO ] QUBO of size 2877 sampled in 0.14s (NEAL, seed=1615186406).
2019-01-29T09:56:51.619 [hepqpr.qallse.track_recreater INFO ] Found 0 conflicting doublets
SAMPLE -- energy: -165.7110, ideal: -163.1879 (diff: -2.523028)
          best sample occurrence: 1/10
SCORE  -- precision (%): 99.1769547325103, recall (%): 99.1769547325103, missing: 2
          tracks found: 48, trackml score (%): 99.38064159235999
Wrote response to /tmp/mini/neal_response.pickle

# plot the results
qallse -i /tmp/mini/ds05/event000001000-hits.csv -o /tmp/mini plot -r /tmp/mini/neal_response.pickle

Solving QUBOs with qbsolv and D-Wave

qbsolv logs: the qallse qbsolv commandline tool is quite rich. Here is an example on how to visualise the main loops of qbsolv (using the qubo created in the previous section):

# !!!!!!!! ensure there no buffered io !!!!!!!!

# get the qbsolv logs into a file (verbosity should be at least 3)
qallse -i /tmp/mini/ds05/event000001000-hits.csv -o /tmp/mini qbsolv \
    -l /tmp/qbsolv.log \
    -v 4
# plot the energies after each main loop
parse_qbsolv -i /tmp/qbsolv.log

D-Wave: the only thing you need is a valid D-Wave configuration file (you can create an account on the D-Wave LEAP cloud platform to get 1 minute of QPU time for free). Then, simply use the -dw option and that's it ! The sub-QUBOs are now solved on a D-Wave:

qallse -i /tmp/mini/ds05/event000001000-hits.csv -o /tmp/mini qbsolv \
    -dw /path/to/dwave.conf


The examples directory contains some examples on how to do everything from scripts instead of using the commandline.

Other very useful functions are available in hepqpr.qallse.cli.func and pretty self-explanatory.

Running from an IPython notebook

Just create a conda environment and to install the package using (see conda doc).

To get the output of qallse in the notebook, use:

import logging
# turn on logging
# optional: display the time as well
fmt = logging.Formatter("%(asctime)s.%(msecs)03d %(levelname)s %(name)s: %(message)s", datefmt='%H:%M:%S')
for handler in logging.getLogger().handlers: handler.setFormatter(fmt)
# set the logging level for qallse

See the notebook example for more information.


The plotting module

You can use hepqpr.qallse.plotting for plotting doublets and tracks easily.

Jupyter: if you are running in a notebook, you need to tell the module so by calling set_notebook_mode().

The methods take a DataWrapper and a list of xplets (an xplet is here a list of hit ids). The argument dims lets you define the plane to use (2D or 3D). The default is xy. A lot more options are available, just look at the source.

Typical usage:

from hepqpr.qallse import DataWrapper
from hepqpr.qallse.cli.func import process_response
from hepqpr.qallse.plotting import *

set_notebook_mode() # if running inside a notebook

# load the dataset and the response (created using the qallse tool)
dw = DataWrapper.from_path('/path/to/eventx-hits.csv')
with open('/path/to/response.pickle', 'rb') as f: 
    import pickle
    response = pickle.load(f)

# process the response and get the set of missing doublets
final_doublets, final_tracks = process_response(response)
precision, recall, missings = dw.compute_score(final_doublets)

# plotting examples
iplot_results(dw, final_doublets, missings)
iplot_results(dw, final_doublets, missings, dims=list('zr'))
iplot_results_tracks(dw, final_tracks)

Exporting plots as pdf

Use the return_fig argument to get hold of the Figure object, then use the orca tool as described in the plotly documentation. Note that extra arguments are passed to the plotly layout object constructor. Here is a complicated example:

import as pio

fig = iplot_results(
    dw, final_doublets, missings, 
    yaxis=dict(range=[0, 1100]), # clip the Y axis
    xaxis=dict(range=[-500, 500]), # clip the X axis
    width=600, height=700, # change the figure size
    legend=dict(font=dict(size=16)), # bigger font in legend
    show_buttons=False, # don't show the interactive buttons
    shapes=xy_layer_shapes, # draw the layers
    return_fig=True # return the figure object

pio.write_image(fig, '/tmp/foo.pdf')

Further information


This code is intended to work on chunks of events from the TrackML dataset, which is representative of real HEP experiments.

When creating chunks/new datasets, the following simplifications are performed:

  1. remove all hits from the endcaps;
  2. keep only one instance of double hits (i.e. duplicate signals on one volume from the same particle).

Then, a given percentage of particles and noisy hits a selected to be included in the new dataset. The weight used to compute the TrackML score are potentially modified ignore low pt and/or short particles (default cuts: <1 GeV, <5 hits) ==> focused and unfocused particles.

A command line script, create_dataset is available. See the file src/hepqpr/qallse/dsmaker/ for more details.


The metrics used through the project are the TrackML score (computed using the trackml-library), the precision and the recall (see wiki).

In this project:

  • precision = (number of focused doublets found) / (number of doublets in the solution - number of unfocused doublets found)
  • recall = (number of focused doublets found) / (number of true focused doublets)


Just as in the TrackML dataset documentation, we try to stick to particles for the truth and to tracks or tracks candidates for reconstructed particle trajectories.

Doublets classifiers:

  • true: when directly coming from the truth file;

  • real: when corresponding to a true doublet. A real doublet can be:

    • focused or
    • unfocused

    depending on whether it belongs to a focused particle (depends on the pt and length cuts applied during dataset creation) or not;

  • fake: a doublet that is not real;

  • missing: a true doublet missing from the solution.





This code was produced during my Msc Thesis at the Lawrence Berkeley National Lab (LBNL). The subject:

This MSc thesis studies the applicability of a special instance of quantum computing, adiabatic quantum optimization, as a potential source of superlinear speedup for particle tracking. The goal is to develop a track finding algorithm that runs on a D-Wave machine and to discuss the interest of Quantum Annealing as opposed to more conventional approaches.

Thank you to all the team that made it possible.


The HEPQPR.Qallse project encodes the HEP (ATLAS) pattern recognition problem into a QUBO and solves it using a D-Wave or other classical QUBO libraries (qbsolv, neal). Master's project (2019).








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