Quantum computer vs classical computer
Since the 1940s, the rules of computing haven't changed. Computers have continued to get smaller and faster year after year, but their fundamental operations remain the same. They still obey the laws of information processing, and process information by performing operations on bits. Quantum computers manipulate qubits instead of bits. With superposition and entanglement, the states of multiple qubits become very complex. By harnessing these complex states, quantum computers will be able to solve many problems much faster than today’s computers.
Quantum Computing vs Classical Computing: From Bits to Qubits
The main difference between quantum computing and classical computing is their calculation. Classical computers manipulate ones and zeroes to crunch through operations, but quantum computers use quantum bits or qubits.
A digital computer both stores and processes information using bits, which can be either 0 or 1. Physically, a bit can be anything that has two distinct configurations: one represented by “0”, and the other represented by “1”. It could be a light bulb that is on or off, a coin that is heads or tails, or any other system with two distinct and distinguishable possibilities. In modern computing and communications, bits are represented by the absence or presence of an electrical signal, encoding “0” and “1” respectively.
A quantum bit is any bit made out of a quantum system, like an electron or photon. Just like classical bits, a quantum bit must have two distinct states: one representing “0” and one representing “1”. Unlike a classical bit, a quantum bit can also exist in superposition states, be subjected to incompatible measurements, and even be entangled with other quantum bits. Having the ability to harness the powers of superposition, interference and entanglement makes qubits fundamentally different and much more powerful than classical bits.
An ordinary computer chip uses bits. These are like tiny switches, that can either be in the off position – represented by a zero – or in the on position – represented by a one. Every app you use, the website you visit and the photograph you take is ultimately made up of millions of these bits in some combination of ones and zeroes. This works great for most things, but it doesn’t reflect the way the universe actually works. In nature, things aren’t just on or off. They’re uncertain. And even our best supercomputers aren’t very good at dealing with uncertainty. That’s a problem.
That's because, over the last century, physicists have discovered when you go down to a really small scale, weird things start to happen. They’ve developed a whole new field of science to try and explain them. It’s called quantum mechanics. Quantum mechanics is the foundation of physics, which underlies chemistry, which is the foundation of biology. So for scientists to accurately simulate any of those things, they need a better way of making calculations that can handle uncertainty. Enter, quantum computers.
Unlike advances in digital computing, which add memory capacity or increase the speed of the processor, quantum computing dramatically alters how we solve problems at the fundamental level. Algorithms have to be re-designed from the ground up, and figuring out which problems benefit from using a quantum computer remains an active field of study.
There are many problems where quantum computers are expected to be no better than digital computers. For example, there is no evidence that a quantum computer will be better at running a word processor than a digital computer. Other problems are “easy” for digital computers already, such as multiplying two numbers together. However, for certain problems, quantum computers can offer strong advantages. While multiplying two numbers together is easy for a digital computer, the reverse process (factoring) is much harder. Even the world’s most powerful supercomputers would take years to factor a 400-digit number. In 1994, Peter Shor proved that a large and robust quantum computer would be able to find those factors exponentially faster.
Will quantum computers replace classical computers?
Quantum computers can solve problems that are impossible or would take a traditional computer an impractical amount of time (a billion years) to solve. It’s crucial to leverage the strengths of both to unlock quantum’s full potential. Quantum computing will transform many industries in the next decade. Classical computers will always play a role, however.
Classical computers have unique qualities that will be hard for quantum computers to attain. The ability to store data, for example, is unique to classical computers since the memory of quantum computers only lasts a few hundred microseconds at most. Additionally, quantum computers need to be kept at temperatures close to absolute zero, which is on the order of -270 degrees Celsius (-450 degrees Fahrenheit). All of these challenges suggest that quantum computers are unlikely to become a fixture of most households or businesses.
What can we do with a quantum computer?
It could help develop lifesaving drugs with unprecedented speed, build better investment portfolios for finance, usher in a new era of cryptography, and deliver new applications and developments.
Drug Development: Computational simulations of drug molecules are essential since they cut costs and time, sometimes dramatically. Today, this type of simulation is only possible with relatively small molecules though. If, however, companies are interested in proteins, which often have thousands of constituents, they need to manufacture them and test their properties in real life because today’s computing resources are not sufficient to make an accurate simulation. Quantum simulations could dramatically reduce the costs of development and help bring drugs to the market faster. Nevertheless, since quantum computing always returns a range of possibilities, the optimal molecular structure of a drug will still need to be confirmed with a classical computer.
Optimization Problems: What is the most efficient placement of equipment in a factory? What is the best way to deploy vehicles to ensure an efficient transportation network? What is the best investment strategy for optimal returns in five, 10 or 30 years? These are complex problems for which the best answer isn’t always obvious. With quantum computers, one could dramatically narrow down the possibilities and then use classical computers to get straightforward answers. These problems abound in diverse sectors, from manufacturing to transportation to finance.
Quantum Artificial Intelligence: Billions of dollars are being invested in autonomous vehicles. The aim is to make vehicles so smart that they’re fit for busy roads anywhere on Earth. Although there is a lot of talent working on training AI algorithms to learn how to drive, accidents are still a problem. Quantum AI, which might be a lot faster and more powerful than current methods, may help solve this problem. The benefits might only be reaped in a decade from now, however, since quantum AI is a lot less developed today than quantum simulation or cryptography. Therefore, the majority of AI algorithms will continue to be deployed on classical computers. Although it’s too early to confidently predict right now, it is not unthinkable that most AI will be quantum in a couple of decades.
Cryptography: Today’s security protocols rely on random numbers and number factorization in heights that classical computers can compute to generate a password but rarely solve in order to crack a password. In a few years, though, quantum computers might be so powerful that they could crack any password. That’s why it’s imperative that researchers start investing into new, quantum-safe cryptography. Quantum technology is a double-edged sword, however, in the sense that it won’t only crack every password, but also be able to generate new, unhackable cryptographic keys. The space is moving fast to incorporate this new reality. Since classical computers will remain relevant, it’s imperative that quantum-safe cryptography exists for these too. This is possible, and companies have already started securing their data on classical computers this way.
Quantum algorithms have also been discovered for tasks such as search and optimization, and are waiting for the right hardware to be run on. Researchers are working on algorithms and mathematical models so that in a near future tasks that take a long time today can be executed more efficiently. There are likely many more quantum algorithms that haven’t been discovered yet. Quantum computing is just getting started, we are very much in the early days.
How do I buy stock in quantum computing?
Given the technology's potential, it's certainly understandable why investors are excited about the future of quantum computing. To buy quantum computing stocks, investors should open a brokerage account. Popular online brokerages with access to the U.S. stock market include WeBull, Vanguard, Robinhood, TD Ameritrade, Charles Schwab, Interactive Brokers, eToro, and more.
