# Source code for qutip.qip.qubits

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__all__ = ['qubit_states']

from qutip.tensor import tensor
from numpy import sqrt
from qutip.states import basis

[docs]def qubit_states(N=1, states=[0]):
"""
Function to define initial state of the qubits.

Parameters
----------
N : Integer
Number of qubits in the register.
states : List
Initial state of each qubit.

Returns
----------
qstates : Qobj
List of qubits.

"""
state_list = []
for i in range(N):
if N > len(states) and i >= len(states):
state_list.append(0)
else:
state_list.append(states[i])

return tensor([alpha * basis(2, 1) + sqrt(1 - alpha**2) * basis(2, 0)
for alpha in state_list])