Quantum-Computing-JavaScript

Simulator of an ideal quantum computer in JavaScript. The unitary operations are optimized with matrix-free algorithms. This project is a direct conversion to JavaScript of the QCSim written in Python: https://github.com/lvillasen/Quantum-Computer-Simulator where you can find more examples.

Usage

Clone the repository
Open the file index.html with any web browser

Live Demo

https://ciiec.buap.mx/QCSim

Brief description

This is an ideal simulator.

The maximum number of qubits it can handle is limited, in a natural way, by the resources available on the system used to run the programs.

The gates and commands implemented so far are the following:

• h q[i]; Hadamard gate H applied to qubit i

• x q[i]; X Pauli gate applied to qubit i

• y q[i]; Y Pauli gate applied to qubit i

• z q[i]; Z Pauli gate applied to qubit i

• cx q[i], q[j]; CNOT gate applied to control qubit i and target qubit j

• verbose 0(1); verbose mode off(on)

• sign i; flips sign of states with index i in the standard basis

Lines that do not terminate with a semicolon are treated as comments, they can be merged with code after the ; terminator or in new lines

The code implements an automatic extension of the range of qubits for the commands X, Y, Z and H, for instance

h q[0:4];

is equivalent to

h q[0];
h q[1];
h q[2];
h q[3];
h q[4];

The initial state is |000...00>

As usual, qubits are ordered from right to left on the quantum states |psi>

Examples

The code

Bell state
verbose 1;
h q[0];
cx q[0], q[1];

produces

Number of Qubits = 2
 Scanning .....
 Hadamard gate applied to qubit 0
 resulted in state |psi> =0.707|00> + 0.707|01> 
 CX gate applied to control qubit 0 and target qubit 1
 resulted in state |psi> =0.707|00> + 0.707|11> 
Final State |psi> =0.707|00> + 0.707|11> 

the code

GHZ state
verbose 1;
h q[0:1];
x q[2];
cx q[1], q[2];
cx q[0], q[2];
h q[0:2];

produces

Number of Qubits = 3
 Scanning .....
 Hadamard gate applied to qubit 0
  resulted in state |psi> =0.707|000> + 0.707|001> 
 Hadamard gate applied to qubit 1
  resulted in state |psi> =0.5|000> + 0.5|001> + 0.5|010> + 0.5|011> 
 X gate applied to qubit 2
  resulted in state |psi> =0.5|100> + 0.5|101> + 0.5|110> + 0.5|111> 
 CX gate applied to control qubit 1 and target qubit 2
  resulted in state |psi> =0.5|010> + 0.5|011> + 0.5|100> + 0.5|101> 
 CX gate applied to control qubit 0 and target qubit 2
  resulted in state |psi> =0.5|001> + 0.5|010> + 0.5|100> + 0.5|111> 
 Hadamard gate applied to qubit 0
  resulted in state |psi> =0.354|000> - 0.354|001> + 0.354|010> + 0.354|011> + 0.354|100> + 0.354|101> + 0.354|110> - 0.354|111> 
 Hadamard gate applied to qubit 1
  resulted in state |psi> =0.5|000> - 0.5|011> + 0.5|100> + 0.5|111> 
 Hadamard gate applied to qubit 2
  resulted in state |psi> =0.707|000> - 0.707|111> 

Final State |psi> =0.707|000> - 0.707|111>