10,000 Ft. View — The Quantum Properties

Superposition

You’ve probably heard of the famous Schrödinger’s Cat paradox.

Schrödinger stated that if you place a cat and something that could kill the cat (a radioactive atom) in a box and sealed it, you would not know if the cat was dead or alive until you opened the box, so that until the box was opened, the cat was (in a sense) both “dead and alive”. — Wikipedia

Doesn’t that sound super counter-intuitive? This property of being in two states at the same time is essentially what superposition is.

Superposition is like a spinning coin

Now, imagine a coin with two possible states — heads or tails. When you toss it, only one side can come on top, right? Kind of like binary bits of classical computers — every bit is either a 0 or 1. But what if the coin is actually spinning, where it could be both heads and tails at the same exact time?

What if a bit could be both 0 and 1 AT THE SAME TIME? That’s superposition. Classical bits stored states as a scalar value (0 or 1) whereas Quantum bits (Qubits) are capable of storing states in the form of probabilistic wave functions (a superposition where it is both 0 and 1). And they will only collapse to scalar values when you decide to “measure” the qubits.

The probabilistic waves of superposition

How does superposition exactly make quantum computers powerful, you ask?

At a single point in time Classical Computer with n bits

1st bit — 1 state (0 or 1)

2nd bit — 1 state

nth bit — 1 state

Computer's state = 1^n = 1 Quantum Computer with n Qubits

1st bit - 2 states (Both 0 & 1)

2nd bit - 2 states

nth bit - 2 states

Computer's state = 2^n

As you can see, the ability of each qubit to be in two states at the same time exponentially boosts the capacity of quantum computers to process large computations without space and memory constraints that limit classical computers.

Tip: View superposition as a function rather than a single value.