SECTIONS or CHAPTERS

🆚 1. Quantum Computing vs. Regular Computing
🎆 2. Quantum Properties
🧠 3. Why Quantum Computers Are Better
⚙️ 4. Quantum Circuits
🌲 5. Uses in the Real World

🆚 1. Quantum Computing vs. Regular Computing

Quantum computing is largely different from the regular computing we know today.

🖥️ REGULAR COMPUTERS

A regular computer, as you may already know, use bits. A bit can only be two numbers: 0 or 1. All information you can find online or on your computer, such as images, text, video, even this post you’re reading right now, is made out of long strings of bits, like 011001101000100111101010, except a lot longer.

Operations on a regular computer is performed using logic gates for example (NOT, AND, OR).

To think of it simply, it’s a light switch. ON or OFF. 0 or 1.

🛞 QUANTUM COMPUTERS

A quantum computer does not use bits. Instead, it uses quantum bits, short for qubits.

A qubit can be in:

• |0⟩ (quantum state of zero)
• |1⟩ (quantum state of one)
• or even any combination of both |0⟩ and |1⟩, aka superposition.

A quantum computer is a lot more powerful than the regular computer because it allows a computer to do many processes at once:

• a bit = 0 or 1
• a qubit = infinite states between 0 or 1

• that means with more qubits, you can represent more values simultaneously.

∣ψ⟩=α∣0⟩+β∣1⟩

This equation is a general rule. This is the standard form to describe a qubit in quantum computing. It is how quantum mechanics shows the state of any single qubit.

Don’t worry! That expression looks intimidating, but let me explain it:

• This equation is called a quantum state vector. Every qubit is required to be described like this:

• ∣ψ⟩ (psi) from the left-hand side of the equation is the qubit’s state.
• α∣0⟩+β∣1⟩ from the right-hand side of the equation shows a qubit is a superposition from the two base states:
  |0⟩ and |1⟩
• The variables on the equation, α and β are the amplitudes. They represent how strong the qubit leans to each state.

🎆 2. Quantum Properties

🔗 ENTANGLEMENT

Qubits are able to be entangled. What this means is that what happens to one qubit effects the other qubit. For example, you have two qubits. You change one, the other is immediately affected, even though they are extremely far apart.

Entanglement allows correlations and parallelism between two qubits and data.

📌 SUPERPOSITION

An example of superposition is a coin. Usually, the coin is only heads or tails. But with superposition, it’s both heads and tails. A qubit in superposition is able to easily do multiple calculations at once.

Here’s an example:
Look at these four numbers. 00, 01, 10, 11
If you have 2 regular bits, you can only represent one of the four combinations.
If you have 2 qubits in superposition, you can represent all 4 of the combinations at once.

🤜🏻 INTERFERENCE

Quantum algorithms– they use interference. What exactly does this mean? They use interference to amplify good answers and block out bad answers.

🧠 3. Why Quantum Computers Are Better

Quantum computers are special. They operate a different way than your regular computer which is why they can do complicated processes.

👍🏻WHAT THEY ARE BETTER AT

However, they’re not faster at everything, only specific topics and problems. Quantum computers are good at:

• Searching through data
• Simulations to do with quantum systems
• Large number calculations

⚙️ 4. Quantum Circuits

🚪 REGULAR LOGIC GATES

Regular computers use the following logic gates:

• OR (one or the other)
• AND (one and the other)
• NOT (anything except this)

🧮 QUANTUM GATES

Instead of using logic gates, quantum computers use something known as quantum gates. Here are some instances of quantum gates:

• Hadamard
• CNOT

What do these gates do? Let’s find out.

– HADAMARD GATE –

This gate puts the qubit in superposition. For example, the qubit is in |0⟩ right now. Using the gate, you can make it equal chance to be |0⟩ or |1⟩. Like flipping a coin: before it lands, it is both 0 and 1.

Why is the Hadamard Gate important? It creates superposition. Superposition is one of the key things to quantum computing. Without the Hadamard Gate, your quantum computer would be similar and only slightly more powerful than a regular computer.

– CNOT (Controlled-Not) Gate

This gate is different from the Hadamard Gate. It flips a qubit if the control is |1⟩.

• Control = |0⟩
  OUTPUT: nothing happens
  
• Control = |1⟩
  OUTPUT: flip target

🌲 5. Uses in the Real World

🔢 CRYPTOGRAPHY

Quantum computers can break codes easier than a regular computer, but the reason we have not yet used it because of its stability. We still do not understand much about quantum computers, so sticking to regular computers for now!

🧪 CHEMISTRY

A lot of chemistry is molecules. Molecules are quantum systems, that means it is easier to experiment with them on quantum computers, because it comes naturally with quantum computers.

⚕️ PROBLEMS WITH OPTIMIZATION

Problems related to routes and logistics are categorized as optimization problems. Here’s an example of a problem easy for a quantum computer to solve:

Let’s say there are 15 coffee shops in town, and you want to try all of them using the shortest route. It will be hard for a regular computer to solve this; they have to go every possible path. So, if we use factorial and look how many combinations there are: 15 * 14 * 13 * 12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = 1,307,674,368,000 combinations. A regular computer would take quite a while calculating the shortest path through all the combinations…

📔 IN SUMMARY

Quantum computers are not ready for public use and are still under development because of complexity. We still do not know much about them! But in the near future, we may be using quantum computers instead of regular computers!

That’s all for today. A quite confusing topic indeed… see you next time!