Quantum mechanics is the study of the properties of subatomic particles and their interactions with energy. Quantum mechanics describes characteristics of both particles and waves, becoming a “wave-particle duality”. This is the second article in our “Intro to quantum mechanics” series, and we will now explore the concept of quantum entanglement.
Quantum Entanglement Defined
Quantum entanglement is a counter-intuitive concept to understand. It is common to think that particles that are spread far from one another will have no direct links with one another. However, in the world of quantum mechanics, two subatomic particles can be intimately linked to each other, even if separated by billions of light-years of space. This means that if there is a change in one of the particles, the other particle will be directly affected by the change. However, the quantum state of the system as a whole can be described.
In quantum entanglement, quantum particles have a property called spin, which can be measured as either down or up (0 or 1). If two particles are connected and one is measured to spin up, the other particle will have a down spin. Changing the spin of one qubit (short for quantum bit) in one direction will change the spin of the other in the opposite direction, no matter the distance between the two particles.
Quantum entanglement occurs when a particle system exists in a "superposition" of multiple states. In other words, the particles can be in many different possible states at the same time. Superposition refers to the multitude of possibilities available to qubits. In other words, a qubit can exist in a combination of various states at once. These two concepts, entanglement and superposition, are intertwined. When an entangled particle is in a state of superposition, each of its entangled connections is also in a superposition state. This interconnectedness leads to the enhanced computational power of quantum computers.
The discovery of quantum entanglement was made by Albert Einstein and Erwin Schrödinger back in the 1930s. Perplexed, Einstein famously called this phenomenon “spooky action at a distance”. Einstein and Schrodinger used entanglement in 1935 to prove that quantum mechanics is not a complete theory. However, well-established experiments proving the existence of entanglement were done by John Clauser in 1970, and further experiments proved this phenomenon to be true.
Applications of Quantum Entanglement
The concept of quantum entanglement is used for communications and in quantum computing. In quantum computing, changing the state of an entangled qubit will instantaneously change the state and or direction of the paired qubit, leading to enhanced processing speeds. This significantly improves the power and efficiency of the processing of computers, which can be used in quantum cryptography, superdense coding, quantum teleportation, etc.
In the realm of communication, entangled qubits offer a means to establish instantaneous agreements on information over extensive distances. However, it's important to note that despite this instantaneous agreement, the information exchange does not exceed the speed of light.
Fun facts
Quantum entanglement is not faster than the speed of light!
Quantum entanglement can occur with multiple particles.
Quantum entanglement was used to prove the incomplete theory of quantum mechanics.
Einstein called entanglement “spooky action at a distance.”
Works Cited
Caltech (2023). What Is Entanglement and Why Is It Important? [online] Caltech Science Exchange. Available at: https://scienceexchange.caltech.edu/topics/quantum-science-explained/entanglement.
Emspak, J. (2022). Quantum Entanglement: Love on a Subatomic Scale. [online] Space.com. Available at: https://www.space.com/31933-quantum-entanglement-action-at-a-distance.html.
Emspak, J. and Hickok, K. (2022). What is quantum entanglement? [online] Space.com. Available at: https://www.space.com/31933-quantum-entanglement-action-at-a-distance.html.
Energy.gov. (2023). DOE Explains...Quantum Mechanics. [online] Available at: https://www.energy.gov/science/doe-explainsquantum-mechanics.
Hurley, W. and Smith, F. (2023). What Are Superposition & Entanglement in Quantum Computing. [online] dummies. Available at: https://www.dummies.com/article/technology/computers/what-are-superposition-entanglement-in-quantum-computing-300563/.
Voorhoede, D. (2021). Superposition and entanglement. [online] Quantum Inspire. Available at: https://www.quantum-inspire.com/kbase/superposition-and-entanglement/.
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