How Does Quantum Computing Work?

How does a qubit work? What makes quantum computers superior? How does quantum computing even work? Quantum computing is complex, so it’s no surprise you have questions. It might seem too complicated to learn, but we broke it down into easy-to-understand segments. Here’s everything a beginner needs to know about quantum technology. 

Quantum Computing Versus Classical Computing

So, how does quantum computing work? You need a basic working knowledge of classical computing to understand how quantum computing works. A regular computer uses bits — the smallest unit of data it can process and store. Its central processing unit registers these electrical signals as either on or off. 

A bit is always represented as either a one or a zero. This is because binary code — the primary language of computers — uses only two digits. Even though only two states exist, they can represent many more numbers. 

Ones and zeroes have meaning when put into a series. You can even translate them into English using the American Standard Code for Information Interchange. For example, 01101000 01100101 01101100 01101100 01101111 is “hello” and 01010010 01100101 01001000 01100001 01100011 01101011 represents “ReHack.”

Quantum computers use the quantum equivalent of bits. As with binary code, these quantum bits — qubits, for short — have just two possible states. However, unlike regular bits, they exist in both states at once, thanks to quantum principles. 

Wait, what is a qubit? A qubit is created by manipulating quantum particles — subatomic particles with unique properties — like electrons, trapped ions or photons. They interact with each other differently than regular objects. They’re effectively the building blocks of quantum computing. They’re also what makes these computers so fast.

An Introduction to Quantum Computing Basics

Now that you’re familiar with the difference between classical computing and quantum computing, let’s go a little further and explore the quantum principles behind qubits.

Superposition

How do qubits work? They exist as both a one and a zero until you measure them. Since quantum particles have wave-like properties, they can overlap. When they’re in superposition, the two different states represent two equally possible outcomes. Until you measure them, they exist in both states simultaneously. If you need help visualizing it, think of Schrodinger’s cat.

Entanglement

Quantum entanglement is pretty straightforward. When quantum particles in a quantum system have the same energy value, they can’t be separated. They’re indistinguishable from one another. No matter how far apart they are — even light-years away — they remain dependent on each other. A change that affects one also affects the other. 

Interference

Remember those wave-like properties quantum particles have? Think of quantum interference like dropping stones in water. When the ripples overlap, some will fade away and some will grow stronger. The technical terms for this process are destructive or constructive interference. You use this phenomenon to determine the probability of an outcome. 

Decoherence 

Quantum coherence is a system’s ability to stay stable and predictable. As you might’ve guessed, decoherence is the loss of quantum coherence. When you measure a quantum particle, it immediately collapses into one definite state. Remember, superposition works like Schrodinger’s cat — if you open the box, the only possible outcome is the one you see.

Wait, How Does Quantum Computing Actually Work?

Even though you now know how qubits work and what role quantum principles play, there’s still more to the process. The mechanics behind how quantum computing works on a technical level are complex, but we’ll try to keep it simple. First off, quantum computers trap ions or contain subatomic particles like electrons. 

Using lasers or microwave beams, you manipulate those superposed quantum particles. Since entangled qubits are intrinsically connected, you only need to measure one to immediately know precise information about the rest. This mitigates the chance of decoherence, meaning you’re less likely to experience errors. 

Entanglement generates interference between the two states — as directed by the quantum algorithm — which weakens or amplifies waves. You can measure the superposed qubits’ probability amplitudes. Think back to the stone-in-water analogy. The coherent “ripples” are the most probable, meaning they’re most likely the correct solution.

The Technical Details Behind Quantum Computers

A quantum computer is a lot different from its classical counterpart. It doesn’t have a screen, keyboard or mouse. That said, researchers may use regular computers to monitor things like waveforms or electromagnetic pulses. They have specialized hardware for containing and manipulating qubits.

Why do quantum computers look nothing like their predecessors? Functionality and stability are the main driving factors. They usually hang from a ceiling to make cooling easier. Qubits are very, very sensitive. Even thermal noise — the sound electrons make when moving — is enough to create unexplainable errors. 

Quantum computers must be kept at negative 459 degrees Fahrenheit to prevent the unexpected loss of quantum coherence. The mess of gold wires, glass tubes and metal disks suspended from the ceiling may look odd, but it helps researchers keep everything cool. Typically, the entire structure is encased in some sort of cylindrical tubing for the same reason.

Now You Know How Quantum Computing Works

The jump from classical to quantum computing was as big as the shift from pen and paper to early computers, so it’s no surprise everything is so complex. A quantum machine can be confusing even if you’re familiar with today’s PCs. Luckily, you should now have a solid understanding of how they work.