# Quantum Computing at a glance: What, Why, When, Where, and How to get started?

*Why do we need Quantum Computing? When can we access an actual Quantum computer?Where are we now? And How to get started?*

We will together address these questions in this blog post to help you *get a feel* for the current state of quantum computing — a promising paradigm shift in the near future.

# What is Quantum Computing?

Quantum computing is based on the theory of

quantum mechanics, and therefore, isfundamentally differentfrom classical computing.

**Wait, what is quantum mechanics?** Quantum mechanics is a branch of physics to actually explain the nature of phenomena at the scale of atoms.

**But why fundamentally different?**

We could start to answer this question from the basic unit of the classical computer and quantum computer: **bits** and quantum bits (or **qubits**). As we have learned, the fundamental unit of information in today’s computer is the bit, which could be either 0 or 1 (we could call they are states). In other words, we could break every digital information into 0s and 1s. `10010`

is the bit representation of 18, for example. However, quantum data are made up of qubits, which could be `0`

, `1`

, or a combination of `0`

and `1`

at the same time (we called a ** superposition** state). That means, with 1 qubit, we could have 2 states simultaneously. How about if we have 3 qubits? - 8 states, right? 10 qubits? 1024 states at the same time with the quantum computer while it still is 1 state once with the classical solution.

Along with superposition, quantum computing has another important characteristic called **entanglement**. We can simply think about an example of entanglement in a special situation, in which 2 qubits are *strongly correlated *regardless of how far away they are. Strongly correlated means that one qubit could always determine the state of the second qubit without interacting with the second one. Looks like we could transfer the quantum information faster than the speed of light using entanglement. It is really *“spooky”* (as Einstein dubbed it).

Exploiting this characteristic, we could take *exponential* speed-up when using quantum computing to solve some intractable issues of today’s computers. A bit fancy, but it’s not an easy game, there are many things we need to learn and control before achieving all the quantum advantages. We will discuss more in later posts, don’t make it complicated at the beginning 🥲

# Why do we need Quantum Computing?

For some problems, supercomputers aren’t that super.

Quantum computing is a promising technology to solve multiple intractable tasks even with “classical” supercomputers. For example, factorizing a large number into prime factors, which is the *“Achilles heel” *of crypto algorithms like RSA, could be “impossible” with the most powerful supercomputer. However, it’s not the rough way for quantum computers in near future by utilizing Shor’s algorithm. This security risk has urged the emergence of another field called Post-Quantum Cryptography to develop quantum-resistant crypto algorithms.

Apart from cryptography, quantum computing could be a solution for many prominent areas such as chemistry, finances, machine learning, networks, and communications. That’s why more countries now put quantum computing on top of their national strategy to prioritize large investments.

# When can we access an actual Quantum computer?

**Now!** Why not? 🤔

Actually, several years ago, we can get access to real quantum computers developed by IBM. The most popular way to run a program on a quantum computer is through a cloud service, provided by some well-known vendors, such as IBM Quantum, Amazon Braket, and Azure Quantum. That means you can write your quantum application at your local computer and then send them to a quantum cloud service for execution, then wait for the results. If you want to learn and try using a quantum computer, go ahead to IBM Quantum — you can send your first quantum job to (up-to) 5-qubit quantum computers for **FREE**! Yup. We still have Free access to some quantum computers provided by IBM Quantum at the moment.

# Where are we now on the Quantum Race?

We are now staying in the **NISQ** — *Noisy Intermediate-Scale Quantum* era. That simply means the *quantity* and *quality* of qubits are not good enough to apply to practical problems at the moment. However, we witnessed numerous advancements in developing quantum hardware recently. The most powerful quantum computer presently (April 2022) is released by IBM last year with 127 qubits — a big milestone for the future of quantum computing. They also targeted to develop an 1121-qubit quantum computer by the end of next year, 2023. Google also claimed that their quantum computer just needs 200 seconds to solve a 10,000-year problem of the world’s fastest supercomputer in 2019. They called it “ *quantum supremacy*”. Moreover, many research topics related to quantum computing becoming trending and very “hot” topics recently, such as *Quantum Machine Learning,* and *Quantum Error Correction*.

# How can we get started learning Quantum Computing?

When I started learning Quantum computing, I found this interesting quote:

Quantum computing isfundamentally differentfrom classical computing. To master quantum computing, you must unlearn what you have learned.Frank Zickert (PyQML)

😱 But don’t worry too much!

You will realize what you should do if you really deep dive into it!

Nowadays, we can learn almost anything new by ourselves in many ways. There are many resources to learn about quantum computing, and it depends on your curiosity, how deep you want to dive in and how you intend to use quantum for your work.

- If you would like to get a bit more “feeling” about quantum computing and quantum mechanics, check out a website called
**Quantum Country**(by Andy Matuschak and Michael Nielsen). - If you want to have a solid understanding of quantum, read the quantum “
*bible*” entitles**Quantum Computation and Quantum Information**by Isaac Chuang and Michael Nielsen. - If you want an interactive textbook to learn Quantum computing in a more practical way and start to write your first quantum program using your Python skill, check out Qiskit Textbook.

Just named a few, but there are numerous good books, online courses, tutorial videos, and documentation available.

Check out my **Quantum Awesome list** to learn more!

If you are really interested to learn, defining your keywords and your Google-ing skill will definitely help.

*Happy learning!*

*Originally published at **https://hoaio.com** on May 27, 2022.*