Albert Einstein famously referred to quantum entanglement as “spooky action at a distance” due to its strange behavior that appears to break one of the fundamental rules of the universe, the speed of light.
What scientists have observed is that once two or more particles are entangled a change in one particle’s spin is instantaneously reflected in any entangled particle, no matter the distance between them. So, two particles could be separated by light years — one on each side of the universe — and a change in one would instantaneously be reflected in the other.
How and why this data transfer happens continues to stump the world’s greatest minds. However, this has not stopped engineers from exploiting the phenomenon to build entirely new types of computers, communication platforms, and even “teleport” information.
Entanglement in quantum computers
Entanglement is a cornerstone process for the operation of quantum computers. According to Microsoft’s Azure Quantum, “entanglement is used to enable quantum parallelism, which is the ability of quantum computers to perform multiple calculations simultaneously.”
While classical computers use bits to compute, quantum computers use what are called qubits.
Success
You are now signed up for our newsletter
Success
Check your email to complete sign up
A qubit, or quantum bit, is the basic unit of quantum information in quantum computing. Unlike a classical bit, which can be either 0 or 1, a qubit can be in a state of 0, 1 or both simultaneously, thanks to a property called superposition. This allows quantum computers to perform complex calculations more efficiently than classical computers.
Microsoft explains how it exploits quantum entanglement this way, “Consider two qubits that are initially prepared in an entangled state. If a measurement is made on one of the qubits, and it is found to be in the state |0⟩, then the state of the other qubit immediately collapses to the state |0⟩ as well. Similarly, if the first qubit is measured to be in the state |1⟩, then the state of the second qubit collapses to the state |1⟩ as well.”
Entanglement allows quantum computers to implement various functions and algorithms that would be impossible to perform on a classical computer. It allows for quantum teleportation — which we will explore further a little later — which, according to Microsoft’s Azure Quantum, “allows for the transfer of quantum states between two distant systems.”
Entanglement is also central to error correction in quantum computers. Error correction is necessary to ensure the information output of quantum computers is correct and it protects the information from decoherence.
Simply put, decoherence occurs when a qubit loses its quantum properties, like superposition, due to interactions with its environment. This causes the qubit to behave more like a classic bit which can disrupt computations.
Environmental factors that can lead to decoherence include interactions with an electromagnetic field, a collision with another particle or temperature fluctuations. These types of interactions interrupt the qubits state, leading it to lose coherence.
In short, quantum computers, which will solve complex problems much more efficiently than classical computers, enhance cryptography and security, optimize large systems like supply chains, and advance fields like medicine, would be impossible without the phenomenon of quantum entanglement.
READ MORE:
- The Quantum Internet Is Emerging; What Is It and What Can We Expect?
- Senate Passes Bill Investing Billions in Next-Generation Tech to Counter China, Spur Innovation
- Washington Puts Chinese Quantum Computing Firms On Blacklist
Quantum communication
Quantum entanglement could one day improve communication by allowing people, and computers, to share information over incredible distances in a way that is both secure and instantaneous.
Imagine being on Earth and communicating with a distant colony on Mars. Communicating at those distances would be very difficult and laggy with current technology. Currently, it takes a signal to travel from Mars to Earth an average of 13 minutes. When Mars is closest to Earth it takes about three minutes, and when it is at its furthest distance from Earth it takes around 20 minutes.
Exploiting quantum entanglement would eliminate this lag-time entirely, allowing for instantaneous communication with far-off colonies.
The quantum internet — currently under construction in the United States — also relies on quantum entanglement.
The phenomena is being used to develop this next generation internet by ensuring secure communication channels between distant nodes in the network.
Using entangled qubits, information can be transmitted both securely and instantly.
The U.S. Department of Energy (DoE) began work on the new infrastructure in July 2020 when then Under Secretary for Science, Paul Dabbar announced America’s Blueprint for the Quantum Internet.
Currently, developers have conducted successful experiments in quantum communication over longer distances and have managed to connect multiple quantum devices.
Quantum Teleportation
Quantum entanglement also allows for a process called, “quantum teleportation.”
It’s not teleportation in the classical sense, like what you would see on Star Trek, but does share a few similarities with it.
It’s a process that allows the transfer of information from one place to another without moving the physical particles themselves.
So, unlike classical computers, that transmits physical packets from one device to another over a network, with quantum teleportation nothing physical is transmitted.
Again, this would be impossible without quantum entanglement.
With quantum teleportation when one piece of entangled information’s state is changed, the entangled partner reflects that change instantly, no matter how far it is away.
This allows the original state to be recreated at the new location, effectively “teleporting” the information.
Researchers are still exploring the fundamental nature of entanglement, a phenomena that goes against our everyday experiences and intuition about how objects should behave.
Quantum theory, and all of its principles, are often counterintuitive, making them very difficult to grasp. The math behind quantum principles is extraordinarily complex and experimenting with quantum principles is both technically demanding and difficult to do properly.
