Quantum computing is a technology that’s often wrapped in mystery. This is because to the experts who are already knee-deep into the tech, it’s hard to take the quantum out of them to explain in a way that regular folks like us understand.
It’s akin to asking doctors to describe the liver without saying “hepato”. Their mouths might cramp up trying.
Even common analogies like comparing quantum computing to a spinning coin don’t always do the job. So let’s try to change that.
What are quantum computers?
Quantum computers are not just faster versions of normal computers – they are a completely different kind of machine. They process mind-blowing amounts of data using the principles of quantum physics, solving problems that could take normal computers days, months or years – in a matter of seconds.
How they work is where it gets a bit tricky. But stay with me. Take a deep breath.
How do quantum computers work?
Let’s use the example of a multiple-choice question.
Which of these is the capital of Malaysia?
- Penang
- Singapore
- Bali
- Kuala Lumpur
Normal computers approach this question like we do – by process of elimination. We read the question, eliminate answers we know are wrong, and land on what we believe is right.
Quantum computers read the question, then all four answers, and eliminate all the wrong answers simultaneously. Then they give you the most probable correct answer.
In case you are curious, the jargons for reading the four answers and eliminating all the wrong answers at a go are called Superposition and Interference. The most probable answer is called Measurement.
How they do this superpositioning and interference? It’s by qubits.
What are qubits?
Qubits are quantum bits. When quantum scientists and researchers run tests, they tend to select the number of qubits to entangle to solve complex problems.
Entanglement is when two or more qubits are connected together. This means that when working on a problem, they know what each other is thinking, constantly checking in with each other, and helping eliminate wrong answers to surface the most likely right one.
The more qubits are connected, the higher the chance of getting an accurate result. But it’s easier said than done. The more qubits you connect, the harder it is to keep things stable – and instability can disrupt the calculation and lead to wrong answers. That’s why, in today’s climate, it’s usually done in a controlled setting and scaled up gradually.
Why “most probable answer”?
If you have not realised, I did not say quantum computers give you the correct answers but most probable answers – because that’s just how quantum physics work.
Quantum computers work on probability and pattern to determine the best answers. Will it be inaccurate? Yes. That’s why often there’s a need to prompt quantum computers on the same question over and over and over again. If after 1,000 reruns, 984 times give you the answer of Kuala Lumpur, the probability that Kuala Lumpur is the right answer is high. Thus, Kuala Lumpur is the most probable answer.
Oh! This is just like what Dr Strange said in the movie, Avengers: Infinity War –
“I looked forward in time… I saw 14,000,605 possible outcomes.”
He didn’t just guess. He reran all those possible futures to find the one where they beat Thanos.
That’s what a quantum computer does – it doesn’t guess blindly. It explores every possibility, cancels the bad ones, and finds the best outcome.
Perhaps a better example: cracking passwords
Maybe this multiple-choice question doesn’t fully show the power of quantum computers. So let’s use a more practical one – cracking passwords.
Say you have a password that’s 8 characters long with letters and numbers. The possible combinations are 200 billion. To crack the password with brute force using normal computers, it could take potentially centuries.
With quantum computers, they can superposition many combinations at the same time and cancel out wrong ones using interference to surface possible correct combinations.
This is what keeps a lot of organisations – like the banks – up at night.
Of course, there are ways to counter using quantum methods like quantum key distribution and post-quantum cryptography. But this is a story for another day.
Summing it up…
Quantum computers are difficult to understand. But it’s not impossible.
- They are a new kind of computer that allows fast processing of huge amounts of data in seconds.
- Qubits are how quantum computers can read and eliminate wrong answers concurrently, to surface the most probable answers.
- And if misused, quantum computers could be powerful enough to crack passwords without breaking a sweat.
So what do you think? Do you know what quantum is now? More a video person?
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