Qulacs

Qulacs is a python/C++ library for fast simulation of large, noisy, or parametric quantum circuits.

Qulacs is licensed under the MIT license.

Quick Install

pip install qulacs

If you have NVIDIA GPU with CUDA installed try:

pip install qulacs-gpu

Feature

• Fast quantum circuit simulation with parallelized C/C++ backend
• Noisy quantum gate for simulation of NISQ devices
• Parametric quantum gates for variational methods
• Circuit compression for fast simulation
• GPU support for fast simulation
• Many utility functions for research

Performance

• Compared processing time with following libraries on October 1st, 2018

  • Qulacs CPU & GPU (ours)
  • Cirq
  • ProjectQ
  • pyQuil
  • Q#
  • Qiskit Terra QASM Simulator
  • Qiskit Aer
  • QuPy CPU & GPU

• Test environment:

  • 100 shot sampling of 10 layers of all random rotation X gate and 9 layers of all neighboring CNOT
  • Intel Core i7-8700 CPU
  • NVIDIA GTX 1050 Ti GPU
  • OpenMP enabled
  • MKL enabled (numpy runs in multi thread)
  • Circuit compression disabled

QuEST and qHiPSTER is also fast circuit simulator but we excluded since it doesn't have python interface.

Supported environment

Qulacs is tested on the following systems.

• OS
  • Ubuntu 16.04
  • MacOS X Sierra
  • Windows 10

The following languages are supported.

• C++
  • gcc/g++ >= 7.0.0
  • Microsoft VisualStudio C++ 2015, 2017
• python
  • python 2.7
  • python 3.x

If you want to use GPU, install CUDA >= 8.0.

Install from Source

If you encounter some troubles, see troubleshooting (Japanese). Currently, if you want to use GPU, qulacs must be installed from source.

Requirements

• C++
  • gcc/g++ >= 7.0.0 (for python on Unix platforms in Linux, MacOS, or Windows)
  • Microsoft VisualStudio C++ 2015 or 2017 (for other python on Windows)
• python 2.7 or 3.x
• cmake >= 3.0
• (optional) CUDA >= 8.0

Install qulacs from source

Install

git clone https://github.com/qulacs/qulacs.git
cd qulacs
python setup.py install

Uninstall

pip uninstall qulacs

Build C++ and python library

GCC

git clone https://github.com/qulacs/qulacs.git
cd qulacs
./script/build_gcc.sh

When you want to build with GPU, use build_gcc_with_gpu.sh.

MSVC

git clone https://github.com/qulacs/qulacs.git
cd qulacs
script/build_msvc.bat

When you want to build with GPU, use build_msvc_with_gpu.bat.

Tutorial and API document

See the following documents for more detail.

• Python Tutorial
• C++ Tutorial
• Examples
• API document

Sample code

Python

from qulacs import Observable, QuantumCircuit, QuantumState
from qulacs.gate import Y,CNOT,merge

state = QuantumState(3)
state.set_Haar_random_state()

circuit = QuantumCircuit(3)
circuit.add_X_gate(0)
merged_gate = merge(CNOT(0,1),Y(1))
circuit.add_gate(merged_gate)
circuit.add_RX_gate(1,0.5)
circuit.update_quantum_state(state)

observable = Observable(3)
observable.add_operator(2.0, "X 2 Y 1 Z 0")
observable.add_operator(-3.0, "Z 2")
value = observable.get_expectation_value(state)
print(value)

If you want to run it on GPU, install qulacs from source and replace QuantumState with QuantumStateGpu.

C++

#include <iostream>
#include <cppsim/state.hpp>
#include <cppsim/circuit.hpp>
#include <cppsim/observable.hpp>

int main(){
    QuantumState state(3);
    state.set_Haar_random_state();

    QuantumCircuit circuit(3);
    circuit.add_X_gate(0);
    auto merged_gate = gate::merge(gate::CNOT(0,1),gate::Y(1));
    circuit.add_gate(merged_gate);
    circuit.add_RX_gate(1,0.5);
    circuit.update_quantum_state(&state);

    Observable observable(3);
    observable.add_operator(2.0, "X 2 Y 1 Z 0");
    observable.add_operator(-3.0, "Z 2");
    auto value = observable.get_expectation_value(&state);
    std::cout << value << std::endl;
    return 0;
}

Build command for g++:

g++ -O2 -I ./<qulacs_path>/include -L ./<qulacs_path>/lib <your_code>.cpp -fopenmp -lcppsim_static.so

If you want to run it on GPU, include cppsim/state_gpu.hpp and replace QuantumState with QuantumStateGpu.