A quantum computer uses quantum physics to do calculations. The reason this is so amazing is that it allows exponentially faster calculation, compared to the digital computer in front of you. To see how this is, recall that normal digital computers use bits, ones, and zeros.
In contrast, quantum computers use Qubits or quantum bits. Quantum bits can exist as both a one and a zero. And so they can do two calculations at once. This may not seem very impressive, but each Qubit has a multiplicative effect.
Ten Qubits can do a thousand calculations at once, and 30 Qubits can do a billion calculations at once. This still doesn’t mean that you just install your favorite app on a quantum computer, and you are ready to go.
The code required for quantum computers is so different, that it needs specialized quantum algorithms to operate. And right now, there aren’t many of these.
The quantum algorithms are usually developed by physicists and mathematicians, and so take advantage of the unique properties of quantum physics. A quantum computer also relies on probability, so the answers it produces may not always be correct. This might seem odd.
How can a computer give an incorrect answer? It’s because, in the world of quantum physics, things are always a bit fuzzy, and the answer may occasionally be wrong. This is why most applications will be hybrid quantum-digital, to combine the speed of quantum with the certainty of digital.
An example might be modeling the chemical process for fertilizer. The digital computer can set up the basic model, and the quantum computer can determine the right energy levels.
Since fertilizer is about 2% of the world’s energy supply, this could have enormous consequences for food production and energy costs.
So, if you’re homework involves some of the most promising applications, cryptography, molecular modeling, financial predictions, yes, you will be doing your homework on a quantum computer.