qsim and qsimh are designed to be extensible to a variety of different
applications. The base versions of each are qsim_base and qsimh_base;
sample extensions are provided in apps. To compile the codes, just run
make. Binaries of the form qsim(h)_*.x will be added to the apps
directory.
Sample circuits are provided in circuits.
./qsim_base.x -c circuit_file -d maxtime -t num_threads -v verbosity
circuit_file - circuit file to run
maxtime - maximum time
num_threads - number of threads to use
verbosity - verbosity level
qsim_base computes all the amplitudes and just prints the first eight of them (or a smaller number for 1- or 2-qubit circuits).
Example:
./qsim_base.x -c ../circuits/circuit_q30 -d 16 -t 8 -v 1
Note that this particular simulation requires 8 GB of RAM.
./qsim_von_neumann.x -c circuit_file -d maxtime -t num_threads -v verbosity
circuit_file - circuit file to run
maxtime - maximum time
num_threads - number of threads to use
verbosity - verbosity level
qsim_von_neumann computes all the amplitudes and calculates the von Neumann entropy. Note that this can be quite slow for large circuits and small thread numbers as the calculation of logarithms is slow.
Example:
./qsim_von_neumann.x -c ../circuits/circuit_q24 -d 16 -t 4 -v 1
./qsim_amplitudes.x -c circuit_file -d times_to_save_results -i input_files -o output_files -t num_threads -v verbosity
circuit_file - circuit file to run
times_to_save_results - comma-separated list of circuit times to save results at
input_files - comma-separated list of bitstring input files
output_files - comma-separated list of amplitude output files
num_threads - number of threads to use
verbosity - verbosity level
qsim_amplitudes reads input files of bitstrings, computes the corresponding amplitudes at specified times and writes them to output files.
Bitstring files should contain bitstings (one bitstring per line) in text format.
Example:
./qsim_amplitudes.x -c ../circuits/circuit_q24 -t 4 -d 16,24 -i ../circuits/bitstrings_q24_s1,../circuits/bitstrings_q24_s2 -o ampl_q24_s1,ampl_q24_s2 -v 1
./qsimh_base.x -c circuit_file -d maxtime -k part1_qubits -w prefix -p num_prefix_gates -r num_root_gates -t num_threads -v verbosity
circuit_file - circuit file to run
maxtime - maximum time
part1_qubits - comma-separated qubit indices for part 1
prefix - prefix value
num_prefix_gates - number of prefix gates
num_root_gates - number of root gates
num_threads - number of threads to use
verbosity - verbosity level
qsimh_base just computes and just prints the first eight amplitudes. The hybrid
Schrödinger-Feynman method is used. The lattice is split into two parts.
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. The path for the prefix gates is specified by prefix. It is
just a value of bit-shifted path indices in the order of occurrence of prefix
gates in the circuit file.
Example:
./qsimh_base.x -c ../circuits/circuit_q30 -d 16 -k 0,1,2,6,7,8,12,13,14,18,19,20,24,25,26 -t 8 -w 0 -p 0 -r 5 -v 1
./qsimh_amplitudes.x -c circuit_file -d maxtime -k part1_qubits -w prefix -p num_prefix_gates -r num_root_gates -i input_file -o output_file -t num_threads -v verbosity
circuit_file - circuit file to run
maxtime - maximum time
part1_qubits - comma-separated list of qubit indices for part 1
prefix - prefix value
num_prefix_gates - number of prefix gates
num_root_gates - number of root gates
input_file - bitstring input file
output_file - amplitude output file
num_threads - number of threads to use
verbosity - verbosity level
qsimh_amplitudes reads the input file of bitstrings, computes the corresponding amplitudes and writes them to the output file. The hybrid Schrödinger-Feynman method is used, see above.
Bitstring files should contain bitstings (one bitstring per line) in text format.
Example:
./qsimh_amplitudes.x -c ../circuits/circuit_q40 -d 47 -k 0,1,2,3,4,5,6,7,8,9,10,13,14,15,16,17,23,24 -t 8 -w 0 -p 9 -r 4 -i ../circuits/bitstrings_q40_s1 -o ampl_q40_s1_w0 -v 1
./qsimh_amplitudes.x -c ../circuits/circuit_q40 -d 47 -k 0,1,2,3,4,5,6,7,8,9,10,13,14,15,16,17,23,24 -t 8 -w 1 -p 9 -r 4 -i ../circuits/bitstrings_q40_s1 -o ampl_q40_s1_w1 -v 1
...
SimulatorBasic can be used on older systems that do not support AVX instructions. In this case, simulator_basic.h should be included instead of simulator_avx.h and SimulatorAVX should be replaced by SimulatorBasic<ParallelFor, float>.