1. braket

1.1. Overview

braket is a tool for simulations of quantum gates on (classical) computers. This document will explain the use of braket with examples of its use on Fugaku.

The supported version of braket on Fugaku is v1.6.0.

For more information about Qulacs, refer to https://github.com/naoki-yoshioka/braket.

1.2. How to use braket

braket is available through Spack, a software package management system for high performance computing.

1.2.1. Preparation of Spack environment

The Spack environment on Fugaku can be constructed based on Fugaku Spack User Guide.

This document explains how to use Qulacs assuming the use of public instances of Spack.

1.2.2. Loading braket

If you use braket, load it with the following command.

$ spack load braket %fj

1.2.3. Unloading braket

If you do not use braket, unload it with the following command.

$ spack unload braket %fj

1.3. Example of Usage

This section shows an example of running braket in a batch job on Fugaku.

1.3.1. Input data

You can obtain the input data of this exanple with the following commands.

$ wget https://github.com/naoki-yoshioka/braket/archive/refs/tags/v1.6.0.tar.gz
$ tar xvf v1.6.0.tar.gz

1.3.2. Creating batch job script

The following batch job script (run.sh) is an example for running Qulacs on Fugaku.

※ For single account users, the execution group id (check with the id command) must be specified in run.sh.

（Example: #PJM -g hp*****）

$ cat run.sh
#!/bin/sh
#PJM -g hp*****
#PJM -L "node=1"
#PJM -L "rscgrp=small"
#PJM -L "elapse=00:20:00"
#PJM --mpi "max-proc-per-node=12"
#PJM -x PJM_LLIO_GFSCACHE=/vol0004
#PJM -S

export PATH=/opt/FJSVxtclanga/tcsds-1.2.36/bin:$PATH
export LD_LIBRARY_PATH=/opt/FJSVxtclanga/tcsds-1.2.36/lib64:$LD_LIBRARY_PATH
. /vol0004/apps/oss/spack/share/spack/setup-env.sh
spack load braket %fj

mpiexec -np 4 bra --mode simple --file qcx/hadamards08.qcx 1> stdout 2> stderr

1.3.3. Execution of batch job

Please submit the batch job script (run.sh) by the following command.

$ pjsub run.sh

1.3.4. Confirmation of result

In the stdout file created under output.job-id, the <Qx>, <Qy>, and <Qz> values in the Expectation values of spins field consistent with the follows, braket is working without problems.

Operations finished: 0.002061 (0.002061)
Expectation values of spins:
  <Qx>     <Qy>     <Qz>
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
 -0.000    0.500    0.500
Expectation values finished: 0.002574 (0.000512)