In quantum computers, our basic variable is the qubit: a quantum variant of the bit.
the same restrictions as normal bits do: they can store only a single binary piece of information, and can only ever give us an output of 0 or 1
Each element in the statevector contains the probability of finding the car in a certain place:
statevectors happen to be a very good way of keeping track of quantum systems, including quantum computers.
This restriction is lifted for quantum bits. Whether we get a 0 or a 1 from a qubit only needs to be well-defined when a measurement is made to extract an output
At that point, it must commit to one of these two options. At all other times, its state will be something more complex than can be captured by a simple binary value.
mutually exclusive
two orthogonal vectors.
|0⟩=[10]|1⟩=[01].
the bra-ket notation, introduced by Dirac.
Since the states |0⟩|0⟩|0\rangle and |1⟩|1⟩|1\rangle form an orthonormal basis, we can represent any 2D vector with a combination of these two states.
the qubit’s statevector
In quantum mechanics, we typically describe linear combinations such as this using the word ‘superposition’.
In Qiskit, we use the QuantumCircuit object to store our circuits, this is essentially a list of the quantum operations on our circuit and the qubits they are applied to.
