Classical vs. Quantum Computing

- Overview

Widespread implementation of quantum computing may still be years away. However, explore the differences between classical and quantum computing to see if the technology will become more widespread.

Quantum computers have four fundamental functions that differ from today's classical computers: 

• Quantum simulation, in which quantum computers model complex molecules.
• Optimization (i.e., solving multivariate problems at unprecedented speed). 
• Quantum Artificial intelligence (AI), with better algorithms, can transform machine learning in different industries like pharma and automotive. 
• Prime factorization, which can revolutionize encryption. 

There are four types of quantum computers currently under development that use: 

• light particles
• trapped ions
• superconducting qubit
• Nitrogen vacancy centers in diamonds

Due to quantum mechanics, quantum computers typically must operate under more regulated physical conditions than classical computers. Classical computers have less computing power than quantum computers and cannot be easily scaled up. They also use different units of data -- classical computers use bits, while quantum computers use qubits.

- Units of Data: bits and bytes and qubits

In classical computers, data is handled in binary. 

Classical computers use bits (a unit of eight bits called a byte) as their basic unit of data. Classical computers write code in binary, either 1 or 0. Simply put, these 1s and 0s represent an on or off state, respectively. They can also indicate true or false, yes or no, for example. 

This is also known as serial processing and is sequential in nature, which means that one operation must complete before another completes. Many computing systems use parallel processing, an extension of classical processing to perform simultaneous computing tasks. A classical computer would also return a result because 1 and 0 bits are repeatable due to their binary nature. 

However, quantum computing follows a different set of rules. Quantum computers use qubits as units of data. Unlike bits, qubits can have a value of 1 or 0, but can also be 1 and 0 at the same time, existing in multiple states at the same time. This is called superposition, where properties can only be defined after they have been measured. 

According to IBM, "superimposed qubits can create complex multidimensional computing spaces," enabling more complex computations. When qubits are entangled, changes in one qubit directly affect the other, which allows for faster information transfer between qubits.

In classical computers, algorithms require massively parallel computing to solve problems. Quantum computers can explain a variety of outcomes when analyzing data with a large number of constraints. Outputs have associated probabilities, and quantum computers can perform more difficult computational tasks than classical computers.

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- The Power of Classical Vs. Quantum Computers

Most classical computers operate based on Boolean logic and algebra, with power increasing linearly with the number of transistors (1s and 0s) in the system. This direct relationship means that in a classical computer, power increases 1:1 with more transistors in the system. 

Because a quantum computer's qubits can represent both 1 and 0, the performance of a quantum computer increases exponentially with the number of qubits. Due to superposition, the number of calculations a quantum computer can perform is 2^N, where N is the number of qubits.

- Operating Environment

Classic computers are great for everyday use and normal conditions. Consider something as simple as a standard laptop. Most people can pull their computer out of their briefcase and use it in an air-conditioned coffee shop or on a porch on a sunny summer day. In these environments, performance for normal use, such as browsing the web and sending e-mail for short periods of time, will not be affected. 

Data centers and large computing systems are more complex and more temperature sensitive, but still operate at what most people would consider "reasonable" temperatures, such as room temperature. For example, ASHRAE recommends that Class A1 to A4 hardware be kept at 18 to 27 degrees Celsius or 64.4 to 80.6 degrees Fahrenheit. 

However, some quantum computers need to reside in tightly regulated and strictly physical environments. Although the first room-temperature computer was recently developed by Quantum Brilliance, some need to be kept at absolute zero, which is around -273.15 degrees Celsius or -459.67 degrees Fahrenheit. 

The reason for the cold working environment is that qubits are extremely sensitive to mechanical and thermal influences. Interference could cause the atoms to lose their quantum coherence (essentially the qubit's ability to represent both 1 and 0 at the same time), which could lead to calculation errors.

- Quantum Computing Facing the Biggest Challenge: Noise

In the past 20 years, hundreds of companies, including giants such as Google, Microsoft, and IBM, have announced the establishment of quantum computing. Investors have invested more than $5 billion to date (2024). All of these efforts have one purpose: to create the world’s next big thing.

Quantum computers use counterintuitive rules to manage matter at the atomic and subatomic levels, processing information in ways that are impossible with traditional or "classical" computers. Experts suspect the technology will be able to impact fields as diverse as drug discovery, cryptography, finance and supply chain logistics.

The promise is certainly there, but so is the hype. For example, some scientists claim that quantum computing will be "bigger than fire and bigger than any revolution humanity has ever seen." Even among scientists, the large number of claims and malicious counterclaims makes it a difficult field to assess.

But ultimately, assessing our progress toward building useful quantum computers comes down to one core factor: whether we can handle the noise. The delicate nature of quantum systems makes them extremely susceptible to the slightest disturbance, whether it's stray photons generated by heat, random signals from surrounding electronics or physical vibrations. 

This noise can wreak havoc, generate errors, and even halt quantum computing. It doesn’t matter how big your processor is, or what your killer app is: Quantum computers will never surpass the capabilities of classical computers unless the noise can be suppressed.