Imagine a computer so powerful it can process data, and solve problems in seconds that would take today’s best computers millions of years. Welcome to the fascinating world of quantum computing! Let’s explore this revolutionary technology in detail, breaking it down in the simplest terms possible to see what makes a quantum computer work.

#### What is Quantum Computing?

If you’re like most of us, when you see the term quantum computing you think, “Oh great, they’re making progress, but I’m not reading that.” In this post, illumy hopes to take some of the intimidation out of the term and get down to the brass tacks of what it is and why it’s relevant. At its core, quantum computing is like regular computing but supercharged. Traditional computers use bits, which are like tiny switches that can be either on or off (represented as 1 or 0). Quantum computers, on the other hand, use qubits. No, not some “where we go one, we go all” conspiracy bits. The name just means quantum bits. Qubits can exist in a state of superposition, meaning they can be both on and off at the same time. This duality is thanks to the principles of quantum physics. Ok, well…that wasn’t very helpful. Don’t give up quite yet!

#### What Exactly is a Bit?

In standard computers, a bit a basic unit of information. Its the smallest unit a computer can process and store in one of two physical states. So, on/off like a light switch? Essentially, yes. Let’s explain:

0: The switch is off.

1: The switch is on.

Then programmers just combine them so computers can represent more complex information. For example:

Two bits: Can represent four possible states (00, 01, 10, 11).

Four bits: Can represent sixteen possible states (0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111).

And so on…

These classical bits are the building blocks of all data in a computer, and by combining a sequence of bits, computers can represent more complex information like numbers, letters, and images.

Eventually, you’ll get up to the 64-bit, 128-bit, 256-bit, 512-bit, etc, that you’re probably used to seeing in regular computer hardware and software. Why did we skip three and go right to four? That’s a really good question and a fair one. Bits are not always even numbers, but the ones we use in traditional computing almost always are. Mostly because of efficiency and standardization. Keeping things in twos also helps when designing and manufacturing hardware. In fact, the number of transistors that can be squeezed onto a silicon chip has been doubling almost every two years since 1970. Some guy even made a “law” about it. You can read about that here if you want to.

However, at some point, this just becomes impractical. It can’t possibly go on forever right? That’s where quantum computing comes in. What if that light switch isn’t just on or off? What if it can be both on AND off at the same time? Bits operating in quantum states. This is where most people get lost, and rightly so. Let’s keep going.

#### The Basics of Quantum Computing

Think of a simple maze on paper. If we ask a classical computer to find shortest route to the end of the maze, it needs to try every single combination of routes through the maze (remember this on/off binary thing?), and pick the winner after its computation cycle is complete. A quantum computer on the other hand, will look the maze in an entirely new way. It will see every route at the same time (on/off together) and determine the winner in much less time. It’s like a novice chess player up against a grandmaster. In quantum computing this is called superposition and entanglement.

#### The Magic of Superposition and Entanglement

**Superposition**

Think of superposition as a spinning coin. In classical computing, your coin is either heads (1) or tails (0). In quantum computing, the coin can be spinning in the air, showing both heads and tails simultaneously. This spinning state allows quantum computers to process a vast amount of information at the same time.

**Entanglement**

Another key principle is quantum entanglement. When qubits –yeah those things– become entangled, the state of one qubit is directly related to the state of another, no matter how far apart they are. Imagine two dice that are tangled up that roll in tandem. They’ll always show the same number when rolled, even if one is on Earth and the other is on Mars. This is kind of like the connection in quantum computers and allows them to solve complex problems much more efficiently.

**Quantum Gates**

*Instructions*: Just like conventional computers use logic gates to perform operations, quantum computers use quantum gates to manipulate qubits.

*Processing*: Quantum gates help qubits process a lot of information at the same time.

#### Cold, Cold, Cold

All of this problem-solving complexity puts out a lot of thermal activity, including noise, and can mess things up if you’re a qubit. These qubits needs to stay cold…VERY COLD. Quantum computers often need to be close to absolute zero (Around 10-20 millikelvin: This is a fraction of a degree above absolute zero (0 kelvin or -273.15°C)) to operate effectively. At these low temperatures the qubits are in a state with the lowest energy possible. They are so cold, that they can’t even contain information about the state they were in milliseconds before. All off this leads to incredible computing power.

These temperatures are achieved using dilution refrigerators, which can cool the qubits to the necessary levels for superconductivity and stable quantum operations. That explains the huge machines you see in the news, with heat exchangers, pumps, copper and stills. They’re not like traditional refrigerators which compress gases to cool food. They evaporate subatomic particles (specifically helium isotopes) into one another and the temperatures go way way down. Imagine instead of throwing a steak into your freezer, you throw it into the middle of Antarctica then decrease that temperature roughly 2.8 times. That’s some serious cold. This incredibly low temperature reduces the chance of outside interference and thermal vibrations which can disrupt the fragile state of qubits and cause errors. It also explains why you can’t build a quantum computer at home.

#### The Early Days of Quantum Physics

The story of quantum computing begins with the strange and wonderful world of quantum physics, discovered in the early 20th century. Pioneering scientists like Albert Einstein, Niels Bohr, and Erwin Schrödinger explored how tiny particles, such as electrons and photons, behave in bizarre and non-intuitive ways.

Quantum physics revealed that particles can exist in multiple states at once and can be entangled over vast distances. These discoveries laid the groundwork for quantum computing, even though the concept itself wouldn’t emerge until decades later.

#### The Birth of Quantum Computing

In the 1980s, physicist Richard Feynman and computer scientist David Deutsch proposed the idea of quantum computers. Feynman realized that classical computers struggle to simulate quantum systems due to their complexity. He suggested that a quantum computer, leveraging the principles of quantum mechanics, could simulate these systems more effectively.

Deutsch further developed these ideas by introducing the concept of a universal quantum computer. He proposed that such a machine could perform any computation that a classical computer could, but exponentially faster in some cases.

#### Quantum Pioneers

**IBM and the Quantum Computing Race**

Fast forward to today, and several pioneers are making quantum computing a reality. IBM has been a significant player, developing quantum computers that are accessible to researchers and developers worldwide. IBM’s Quantum Experience allows users to experiment with quantum circuits on real quantum hardware via the cloud.

**Google’s Quantum Supremacy**

In 2019, Google claimed to have achieved “quantum supremacy.” This milestone means their quantum computer performed a task that would be infeasible for a classical computer in a reasonable time frame. Google’s quantum processor, Sycamore, took about 200 seconds to complete a complex calculation that would take the world’s fastest supercomputer 10,000 years.

**D-Wave Systems and Practical Quantum Computing**

D-Wave Systems, a Canadian company, has also made significant strides. They focus on quantum annealing, a specific type of quantum computing suited for optimization problems. D-Wave’s quantum computers are already being used by companies like Volkswagen for traffic flow optimization and by pharmaceutical companies for drug discovery.

#### Current Uses of Quantum Computing

Quantum computing is still in its infancy, but it’s already making phenomenal strides in several fields:

**Cryptography**

Quantum computers can potentially break the encryption that protects our online data. Classical encryption methods rely on the difficulty of factoring large numbers, a task that quantum computers could perform efficiently using algorithms like Shor’s algorithm. This potential threat has spurred the development of quantum-proof security measures, such as quantum key distribution (QKD), which uses the principles of quantum mechanics to create secure communication channels.

**Medicine**

In the field of medicine, quantum computers can simulate molecular structures with unprecedented accuracy. This capability is vital for drug discovery, where understanding the interactions between molecules can lead to the development of new, more effective drugs. For example, quantum simulations can help identify how a potential drug interacts with its target protein, speeding up the process of finding cures for diseases.

**The Quantum Advantage**

Quantum computers excel at solving complex optimization problems. These problems involve finding the best solution from a vast number of possibilities, a task that classical computers find challenging. For instance, quantum computers can optimize supply chain logistics, financial portfolios, and even traffic flow in cities. D-Wave’s work with Volkswagen to optimize traffic flow in Beijing is a practical example of this application.

#### Future Quantum Computers

The potential future applications of quantum computing are mind-boggling. Here are a few areas where quantum computers could make a significant impact:

**Artificial Intelligence:**Quantum computers could revolutionize artificial intelligence (AI) by processing vast datasets much more efficiently. Machine learning algorithms, which power AI, rely on identifying patterns in large datasets. Quantum computers can handle these computations faster, potentially leading to breakthroughs in AI capabilities, from more accurate voice recognition systems to advanced autonomous vehicles.**Climate Modeling:**Climate modeling involves simulating the Earth’s climate to understand and predict changes. These simulations are incredibly complex, requiring massive computational power. Quantum computers could perform these simulations more accurately and quickly, helping scientists develop better climate models. Improved models can lead to better strategies for mitigating and adapting to climate change.**Material Science:**Quantum computers could lead to the discovery of new materials with extraordinary properties. These materials could revolutionize various industries, from creating more efficient batteries for electric vehicles to developing stronger and lighter building materials. For instance, quantum simulations can help scientists understand and design high-temperature superconductors, which could transform how we transmit and store energy.**Transforming Technology:**Quantum computing will transform the world of technology as we know it. Here’s how:**Enhanced Computational Power:**The immense computational power of quantum computers will enable us to process information, and tackle problems that are currently unsolvable. This capability will drive advancements in fields like cryptography, optimization, and AI, leading to new technologies and solutions we can’t even imagine with today’s computers.**New Industries and Jobs:**As quantum computing technology matures, it will create new industries and job opportunities. From quantum software development to quantum hardware engineering, the demand for skilled professionals in quantum computing will rise. Educational institutions are already beginning to offer specialized programs to prepare the next generation of quantum scientists and engineers.**Revolutionizing Existing Technologies:**Quantum computing will also revolutionize existing technologies. For example, our current internet security protocols will need to be updated to withstand quantum attacks. This transition will drive innovation in cybersecurity, leading to more secure and robust systems. Similarly, advancements in AI and machine learning, powered by quantum computing, will enhance technologies like natural language processing, robotics, and data analysis.

#### Final Thoughts

Quantum computing might sound like science fiction, but it’s rapidly becoming science fact. Ordinary computers may one day be a thing of the past. With its roots in the strange laws of quantum mechanics and the efforts of pioneering scientists and companies, quantum computing is set to achieve some pretty amazing things in everything from AI, to financial transactions, to solving important problems in medicine that are unfathomable today. As we stand on the brink of this new technological era, the possibilities are endless, and the future looks incredibly exciting. So, keep an eye on this space – the quantum revolution is just getting started!

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*Photo by Isabella Fischer on Unsplash*