Q-Sylvan

Q-Sylvan extends the parallel decision diagram library Sylvan (v1.8.0) with MTBDDs and QMDDs (i.e. factored EVBDDs with complex edge weights), as well as functionality to simulate and benchmark quantum circuits.

Installation

Dependencies

Q-Sylvan requires the following libraries: popt, GMP, MPFR and MPC. On Ubuntu these can be installed with

• sudo apt install libpopt-dev libgmp-dev libmpfr-dev libmpc-dev

Compiling the code

After downloading or cloning the repository, from the repository folder the code can be compiled with:

1. mkdir build
2. cd build
3. cmake ..
4. make

Test can be run with ctest.

Example usage

C interface

The following code snippet is a toy example for creating the Bell state |Phi^+> = 1/sqrt(2) (|01> + |10>) using the C interface directly.

// Create |Phi^+>
int nqubits = 2;
QMDD state = qmdd_create_all_zero_state(nqubits);
state = qmdd_gate(state, GATEID_H, 0);     // H on q0
state = qmdd_cgate(state, GATEID_X, 0, 1); // CNOT on c=q0, t=q1
state = qmdd_gate(state, GATEID_X, 0);     // X on q0

// Measure state
bool outcome[] = {0, 0};
double prob;
qmdd_measure_all(state, nqubits, outcome, &prob);

This code can be found in examples/bell_state.c and after compiling the code as described above can be run with ./build/examples/bell_state. A more complete set of available functions can be found here.

Simulation of quantum circuits

Quantum circuits in the Open QASM 2.0 format (see example below) can be simulated using EVDDS with ./build/qasm/run_qasm_on_qmdd <qasm_filename>, or using MTBDDs using ./build/qasm/run_qasm_on_mtbdd. For both, the full state vector can be obtained by including the argument --state-vector. The example circuit below can be found in qasm/circuits/bell_state.qasm. All gates specified in qelib1.inc are supported, as well as measurements. Custom definitions of gates and classical conditioning are currently not supported.

OPENQASM 2.0;
include "qelib1.inc";

// 2 qubit quantum register and 2 bit classical register
qreg q[2];
creg c[2];

// Create |Phi^+>
h q[0];
cx q[0], q[1];
x q[0];

// Measure state
measure q[0]->c[0];
measure q[1]->c[1];

Equivalence checking of quantum circuits

Equivalence checking of two circuits in the QASM format can be done using ./build/examples/circuit_equivalence <qasm_file1> <qasm_file2>. The additional argument --algorithm alternating or --algorithm pauli can be used to use a specific equivalence checking algorithm. By default the alternating algorithm is used.

Documentation

A more complete documentation of the C interface can be found here.

Acknowledgements

This work is supported by the NEASQC project, funded by the European Union's Horizon 2020 programme, Grant Agreement No. 951821.