Skip to content

Commit

Permalink
Add qsim and qsimh simulators.
Browse files Browse the repository at this point in the history
  • Loading branch information
@sergeisakov
sergeisakov committed Feb 7, 2020
0 parents commit 598c0b0
Show file tree
Hide file tree
Showing 80 changed files with 45,360 additions and 0 deletions.
30 changes: 30 additions & 0 deletions CONTRIBUTING.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
# How to Contribute

We'd love to accept your patches and contributions to this project. There are
just a few small guidelines you need to follow, but don't worry about
(or expect to) get everything right the first time! Create a pull request and
we'll nudge you in the right direction.

## Contributor License Agreement

Contributions to this project must be accompanied by a Contributor License
Agreement. You (or your employer) retain the copyright to your contribution;
this simply gives us permission to use and redistribute your contributions as
part of the project. Head over to <https://cla.developers.google.com/> to see
your current agreements on file or to sign a new one.

You generally only need to submit a CLA once, so if you've already submitted one
(even if it was for a different project), you probably don't need to do it
again.

## Code reviews

All submissions, including submissions by project members, require review. We
use GitHub pull requests for this purpose. Consult
[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
information on using pull requests.

## Community Guidelines

This project follows
[Google's Open Source Community Guidelines](https://opensource.google/conduct/).
202 changes: 202 additions & 0 deletions LICENSE
Original file line number Diff line number Diff line change
@@ -0,0 +1,202 @@

Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/

TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

1. Definitions.

"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.

"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.

"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.

"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.

"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.

"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.

"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).

"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.

"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."

"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.

2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.

3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.

4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:

(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and

(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and

(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and

(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.

You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.

5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.

6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.

7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.

8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.

9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.

END OF TERMS AND CONDITIONS

APPENDIX: How to apply the Apache License to your work.

To apply the Apache License to your work, attach the following
boilerplate notice, with the fields enclosed by brackets "[]"
replaced with your own identifying information. (Don't include
the brackets!) The text should be enclosed in the appropriate
comment syntax for the file format. We also recommend that a
file or class name and description of purpose be included on the
same "printed page" as the copyright notice for easier
identification within third-party archives.

Copyright [yyyy] [name of copyright owner]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
93 changes: 93 additions & 0 deletions README.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,93 @@
# qsim and qsimh

Quantum circuit simulators qsim and qsimh. These simulators were used for cross
entropy benchmarking in
[[1]](https://www.nature.com/articles/s41586-019-1666-5).

[[1]](https://www.nature.com/articles/s41586-019-1666-5), F. Arute et al,
"Quantum Supremacy Using a Programmable Superconducting Processor",
Nature 574, 505, (2019).

## qsim

qsim is a Schrödinger full state-vector simulator. It computes all the $$2^n$$
amplitudes of the state vector, where $$n$$ is the number of qubits.
Essentially, the simulator performs matrix-vector multiplications repeatedly.
One matrix-vector multiplication corresponds to applying one gate.
The total runtime is proportional to $$g2^n$$, where $$g$$ is the number of
2-qubit gates. To speed up the simulator, we use gate fusion
[[2]](https://arxiv.org/abs/1601.07195), single precision arithmetic, AVX/FMA
instructions for vectorization and OpenMP for multi-threading.

[[2]](https://arxiv.org/abs/1601.07195) M. Smelyanskiy, N. P. Sawaya,
A. Aspuru-Guzik, "qHiPSTER: The Quantum High Performance Software Testing
Environment", arXiv:1601.07195 (2016).

## qsimh

qsimh is a hybrid Schrödinger-Feynman simulator
[[3]](https://arxiv.org/abs/1807.10749). The lattice is split into two parts
and the Schmidt decomposition is used to decompose 2-qubit gates on the
cut. If the Schmidt rank of each gate is $$m$$ and the number of gates on
the cut is $$k$$ then there are $$m^k$$ paths. To simulate a circuit with
fidelity one, one needs to simulate all the $$=m^k$$ paths and sum the results.
The total runtime is proportional to $$(2^{n_1} + 2^{n_2})m^k$$, where $$n_1$$
and $$n_2$$ are the qubit numbers in the first and second parts. Path
simulations are independent of each other and can be trivially parallelized
to run on supercomputers or in data centers. Note that one can run simulations
with fidelity $$F < 1$$ just by summing over a fraction $$F$$ of all the paths.

A two level checkpointing scheme is used to improve performance. Say, there
are $$k$$ gates on the cut. We split those into three parts: $$p+r+s=k$$, where
$$p$$ is the number of "prefix" gates, $$r$$ is the number of "root" gates and
$$s$$ is the number of "suffix" gates. The first checkpoint is executed after
applying all the gates up to and including the prefix gates and the second
checkpoint is executed after applying all the gates up to and including the
root gates. The full summation over all the paths for the root and suffix gates
is performed.

If $$p>0$$ then one such simulation gives $$F\approx 1/m^p$$ (for all the
prefix gates having the same Schmidt rank m). One needs to run $m^p$
simulations with different prefix paths and sum the results to get $$F = 1$$.

[[3]](https://arxiv.org/abs/1807.10749) I. L. Markov, A. Fatima, S. V. Isakov,
S. Boixo, "Quantum Supremacy Is Both Closer and Farther than It Appears",
arXiv:1807.10749 (2018).

## C++ Usage

The code is basically designed as a library. The user can modify sample
aplications in [apps](apps) to meet their own needs. The usage of sample
applications is described in [docs](docs/usage.md).

### Input format

Circuit input format is described in [docs](docs/input_format.md).

### Sample Circuits

A number of sample circuits are provided in
circuits.

### Unit tests

Unit tests are located in [tests](tests). The Google test framework is used.
Paths to Google test include files and to Google test library files should be
edited in [tests/make.sh](tests/make.sh).

## Cirq Usage

[Cirq](https://github.com/quantumlib/cirq) is a framework for modeling and
invoking Noisy Intermediate Scale Quantum (NISQ) circuits.

To run qsim on Google Cirq circuits, or just to call the simulator from Python,
see [docs](docs/cirq_interface.md).

## Authors

Sergei Isakov (Google): qsim and qsimh simulators, Vamsi Krishna Devabathini
(Google): Cirq interface.

## Disclaimer

This is not an officially supported Google product.
21 changes: 21 additions & 0 deletions apps/make.sh
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
# Copyright 2019 Google LLC. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

#!/bin/bash

g++ -O3 -mavx2 -mfma -fopenmp -lgomp -o qsim1 qsim1.cc
g++ -O3 -mavx2 -mfma -fopenmp -lgomp -o qsim2 qsim2.cc
g++ -O3 -mavx2 -mfma -fopenmp -lgomp -o qsim3 qsim3.cc
g++ -O3 -mavx2 -mfma -fopenmp -lgomp -o qsimh1 qsimh1.cc
g++ -O3 -mavx2 -mfma -fopenmp -lgomp -o qsimh2 qsimh2.cc
Loading

0 comments on commit 598c0b0

Please sign in to comment.