Quantum Supremacy Experiment: Lecture Response

    I have been going to a UBC lecture every thursday for a while. The most recent one was by John Martinis, who is working with Google to build and test quantum computers. The lecture was about an upcoming experiment by him and his team, which will hopefully demonstrate the superior power of quantum computers by checking the results from one with a classical supercomputer.
So what is a quantum computer? Many people have heard of them, but it’s quite hard to understand how they actually work.
    In normal computers, information is stored in the form of ‘bits’, which can either be 1 or 0. The 1s and 0s are processed by millions of tiny electrical switches called transistors, which can either be on or off. Modern consumer grade computers currently can have up to 7.2 billion transistors, and the number is constantly rising- but eventually it has to stop. Transistors are extremely small, and we’re reaching the minimum size; if they were to get much smaller, electricity starts to behave in strange ways- like jumping from wire to wire through a weird process called quantum tunneling.
    This is where quantum computing comes into play.
Instead of the bits of classical computers, quantum computers have Qubits, which, instead of just 1 or 0, can be 1 and 0, and every combination of the two of them.
If a classical bit was a coin sitting on a table, a qubit would be a coin floating in space. Instead of just heads or tails, it could be at any angle or combination of them.
    So what use are qubits? Are they any better than classical bits? They are a lot better. And their power increases exponentially; For example, a processor with just 50 qubits would be almost as powerful as our best supercomputers, while one with around 300 qubits would be able to process every atom in the whole universe (in other words, 1080, or a 1 with 80 zeros after it). While most computers can only do one thing at a time, quantum computers can do millions, which is water makes them so powerful.
    Why don’t we all have quantum computers, then?
First of all, qubits are quite hard to maintain. Current qubits involving superconductors require complex cooling systems to keep them working. But that’s not the main problem; the most difficult thing about qubits is that they aren't necessarily always accurate in their calculations.
Let’s go back to the coin analogy, with the classical bit being represented by a coin on a table. Classical bits might have some randomness or outside interference, but they always have the restoring force of the table underneath keeping them stable. Quantum bits, on the other hand, are floating in space, and any outside interference can cause them to turn any which way, messing up whatever operation they are trying to complete.
    Despite this challenge, qubit technology has come a long way recently, breakthroughs are being made all the time. Hopefully within a few years we will have a working quantum computer!