QCircuits 0.3.0

A package for simulating small-scale quantum computing

Full documentation at www.awebb.info/qcircuits/index.html.

QCircuits is a lightweight Python package for simulating the operation of small-scale quantum computers, based on the quantum circuit model. It uses type (d, 0) and type (d, d) tensors to represent state vectors for and operators on d-qubit systems, rather than using straight vectors and matrices produced by Kronecker products, as is more typical.

Installation

Install with pip:

pip install qcircuits

or from the source available here.

Example usage

Quantum teleportation example:

Quantum circuit:

Code:

import qcircuits as qc

# Instantiating the operators we will need
CNOT = qc.CNOT()
H = qc.Hadamard()
X = qc.PauliX()
Z = qc.PauliZ()

# Alice's hidden state, that she wishes to transport to Bob.
alice = qc.qubit(theta=1, phi=1, global_phase=0.2)

# A previously prepared Bell state, with one qubit owned by
# alice, and another by Bob, now physically separated.
bell_state = qc.bell_state(0, 0)

# The state vector for the whole system.
phi = alice * bell_state

# Alice applies a CNOT gate to her two qubit, and then
# a Hadamard gate to her private qubit.
phi = CNOT(phi, qubit_indices=[0, 1])
phi = H(phi, qubit_indices=[0])

# Alice measures the first two bits, and transmits the classical
# bits to Bob.
# The only uncollapsed part of the state vector is Bob's.
M1, M2 = phi.measure(qubit_indices=[0, 1], remove=True)

# Apply X and/or Z gates to third qubit depending on measurements
if M2:
    print('First bit 1, applying X\n')
    phi = X(phi)
if M1:
    print('Second bit 1, applying Z\n')
    phi = Z(phi)

print('Original state:', alice)
print('\nTeleported state:', phi)

Details