Truly Random Numbers?

If you have a Computer Science background, you may be aware that truly (100% ) random numbers simply do not exist. Random number generation algorithms using classical computers are at, best, reducing the chance of a collision.

Enter Quantum Randomness

While there are several algorithms that can be solved FASTER using quantum computers, there are certain operations that ONLY quantum computers can do. That is, classical computers, cannot, even in principle, perform such operations. One such example is a pure random number generation.

Quantum Randomness

A unitary operator like

    \begin{equation*} Rotation{\theta} = \begin{pmatrix} cos{\theta} & sin{\theta} \\ sin{\theta} & cos{\theta} \\ \end{pmatrix} \end{equation*}

when acting on a stationary state (such as

(1)   \begin{equation*} | 0 \rangle \end{equation*}

)

can place that state into a superposition state (superposition of two states).
This superposition state, when measured, will with PERFECT RANDOMNESS, provide you with a

(2)   \begin{equation*}| 0 \rangle \end{equation*}

or a

(3)   \begin{equation*}| 1 \rangle \end{equation*}

output.

How exactly is a quantum computer implemented?

Imagine a row of atoms aligned in  magnetic field. Imagine this row being bombarded by a light wave. Each atom behaves slightly differently to the incoming wave – and either flips it’s axis – or stays unflipped.

The emerging light wave will contain information about which atoms flipped, and which didn’t.

In effect, this is a quantum calculation. We have an input (the initial state of the row of atoms). And we have an output (the final state, as deciphered from the exiting light wave).