Quantum mechanics is weird, or so you have been told. But what are some of the repercussions of this potentially groundbreaking field of Quantum Computing? We list the more surprising aspects of this field, which are potentially strange compared to classical computers but could radically change how we tackle some of the world’s toughest computational challenges.
Superposition: A Quantum Leap Beyond Binary Logic
The very foundation of classical computing is the binary system, where each bit can be either a 0 or a 1. However, in quantum computing, we move beyond this constraint. Quantum bits, or qubits, can exist in a state of superposition, meaning they can be 0, 1, or both simultaneously. This ability to hold multiple states simultaneously gives quantum computers immense computational power. This principle was introduced by physicist Erwin Schrödinger and is one of the cornerstone concepts in quantum mechanics (Source: “Introduction to Quantum Mechanics” by David J. Griffiths, 2004).
Entanglement: The Spooky Action at a Distance
Quantum entanglement is a phenomenon where the state of one particle becomes intimately connected with the state of another, regardless of the distance separating them. This means that a change in the state of one qubit can instantaneously affect the state of an entangled qubit, no matter how far apart they are. Albert Einstein famously called this “spooky action at a distance.” Quantum entanglement allows qubits that are separated by incredible distances to interact with each other instantaneously (Source: “Quantum Mechanics and Path Integrals” by Richard P. Feynman and Albert R. Hibbs, 1965).
Quantum Parallelism: Solving Many Problems at Once
Because of the principles of superposition and entanglement, quantum computers are able to process a vast number of computations simultaneously. This feature, known as quantum parallelism, allows quantum computers to solve certain problems more quickly than classical computers. For instance, factoring large numbers, which is a complex task for classical computers, can be done significantly faster using quantum algorithms like Shor’s algorithm (Source: “Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer” by Peter W. Shor, 1997).
Quantum Supremacy: Quantum Computers Outpacing Classical Machines
The term ‘quantum supremacy’ (sometimes referred to as ‘quantum advantage’) is used when a quantum computer can solve a problem that a classical computer cannot, or when it can solve a problem significantly faster than a classical computer. In 2019, Google’s quantum computer achieved this milestone by solving a problem in 200 seconds that would have taken the world’s most powerful supercomputer 10,000 years to solve (Source: “Quantum Supremacy Using a Programmable Superconducting Processor” by Google AI Quantum and collaborators, Nature, 2019).
Decoherence: The Quantum Achilles’ Heel
While the principles of quantum mechanics grant quantum computers their power, they also present one of the biggest challenges: quantum decoherence. This phenomenon refers to the delicate state of qubits losing their quantum properties due to interaction with the environment. Maintaining the coherence of qubits for a sufficient period of time (the so-called “coherence time”) to perform calculations is one of the most significant hurdles in quantum computing (Source: “Decoherence, einselection, and the quantum origins of the classical” by Wojciech H. Zurek, 2003).
Quantum Teleportation: Moving Information Instantly
Quantum teleportation is the process of transferring the state of a quantum system from one location to another, without any physical transmission of the system itself. This is achieved by utilizing the principles of entanglement and quantum measurement. It’s important to note that this doesn’t involve teleportation in the traditional sense (as in science fiction), but rather the instantaneous transfer of quantum information. Researchers have successfully demonstrated quantum teleportation experimentally over several kilometres (Source: “Quantum teleportation across a metropolitan fibre network” by Sheng-Kai Liao et al., Nature Photonics, 2016).
Reversibility: Undoing Quantum Operations
In classical computing, many operations are irreversible. For example, if you delete a file, it’s gone. In quantum computing, operations are reversible due to the unitary nature of quantum evolution. This means that for every operation, there is an inverse operation that can undo the effects of the first. This is what allows quantum error correction, a crucial aspect for reliable quantum computing (Source: “Fault-Tolerant Quantum Computation” by Peter Shor, 1996).
No Cloning Theorem: No Copies Allowed in the Quantum World
The no-cloning theorem is a fundamental principle of quantum mechanics which states that it is impossible to create an identical copy of an arbitrary unknown quantum state. This principle has profound implications on quantum computing and quantum information theory. It is one of the key factors that makes quantum communication secure, as any attempt to copy the quantum information would lead to its destruction (Source: “The No-Cloning Theorem” by William K. Wootters and Wojciech H. Zurek, Nature, 1982).
Uncertainty Principle: Precision is Limited
Heisenberg’s uncertainty principle is a fundamental concept in quantum mechanics, which states that it is impossible to measure a quantum particle’s exact position and momentum simultaneously. In the context of quantum computing, the uncertainty principle implies that there’s always some degree of uncertainty involved when we’re working with quantum states. This can make quantum systems challenging to control and manage (Source: “Quantum Mechanics: Concepts and Applications” by Nouredine Zettili, 2009).
To learn more about the implementation of quantum computing, try our simple guide to quantum gates. To start with quantum computing and programming with languages such as Qiskit you can follow our programming guides. Brian Siegelwax has written some great simple guides to quantum programming approached from a non-programmer / non-technical perspective. Brian has reviewed many of the cloud-based quantum programming platforms, such as Classiq, Strangeworks and Q-CTRL, to make it hopefully easier for people to get started!