How do Superconductors work at the Quantum level?

Summary

In this video, Arvin Ash explains the fascinating phenomenon of superconductivity, which was first discovered in 1911 by Heike Onnes. He details how superconductors, when cooled to extreme temperatures, can conduct electricity without resistance, a concept that defies the typical behavior of electrons in metals. The video delves into the quantum mechanics behind this, including Cooper pairs and the Meissner effect, and explores real-world applications like maglev trains. It also touches on recent advancements in the field, such as the creation of room-temperature superconductors, which could revolutionize technology in the future.

Takeaways

• 😀 In 1908, Heike Onnes liquefied helium for the first time, achieving a milestone in low-temperature physics.
• 😀 Onnes discovered superconductivity in mercury by running electricity through it at extremely low temperatures, resulting in no resistance and no energy loss.
• 😀 Superconductors allow current to flow indefinitely with no added energy or voltage, and they expel magnetic fields, causing magnetic levitation.
• 😀 The Meissner effect, discovered in 1933, showed that superconductors expel magnetic fields when cooled in a magnetic environment, leading to levitation.
• 😀 In 1957, Bardeen, Cooper, and Schrieffer developed the BCS theory, explaining the phenomenon of superconductivity with Cooper pairs of electrons.
• 😀 Resistance in materials occurs due to collisions between electrons and atoms, which causes energy loss in the form of heat.
• 😀 At extremely low temperatures, electrons in a conductor pair up to form Cooper pairs, which act as bosons and can flow without resistance.
• 😀 The formation of Cooper pairs leads to superconductivity because these pairs can occupy the same quantum state, unlike fermions which cannot.
• 😀 Superconductivity is lost when the temperature rises above a critical point, disrupting the Cooper pairs due to increased energy.
• 😀 Research on superconductivity is ongoing, with recent advancements like the first room-temperature superconductor in 2020, although it requires extreme pressures to work.

Q & A

What was the significance of Heike Onnes' achievement in 1908?

Heike Onnes' achievement in 1908 was the first successful liquefaction of helium, which was significant because helium liquefies at extremely low temperatures close to absolute zero, which had never been accomplished before.

What did Heike Onnes discover when he ran electricity through a cooled sample of mercury?

Heike Onnes discovered that when he ran electricity through a cooled sample of mercury, it had no electrical resistance, meaning there was no energy loss, leading to the discovery of superconductivity.

What is superconductivity?

Superconductivity is a state of matter in which a material can carry an electric current with zero resistance and no energy loss. It also has the property of expelling magnetic fields, known as the Meissner effect.

How does the Meissner effect relate to superconductivity?

The Meissner effect is the phenomenon where a superconducting material expels magnetic fields. This leads to effects like levitation, where a magnet placed above a superconductor can float due to the expelled magnetic flux.

What is the BCS theory, and how does it explain superconductivity?

The BCS theory, proposed in 1957 by Bardeen, Cooper, and Schrieffer, explains superconductivity by suggesting that electrons form pairs known as Cooper pairs. These pairs behave like bosons, allowing them to move without scattering, resulting in zero resistance.

What role do phonons play in superconductivity?

Phonons, which are collective vibrations of atoms in a lattice, are crucial in the formation of Cooper pairs. Electrons attract phonons, and this interaction helps electrons pair up, which is fundamental to the phenomenon of superconductivity.

Why does resistance occur in regular conductors?

Resistance in regular conductors occurs because electrons scatter off vibrating atoms and lattice imperfections, losing energy in the process, which results in heat and energy dissipation.

What is the Pauli Exclusion Principle, and how does it relate to fermions?

The Pauli Exclusion Principle states that no two fermions (particles with half-integer spin, like electrons) can occupy the same quantum state simultaneously. This principle explains why electrons in atoms or solid matter do not collapse into the same state.

What is the significance of Cooper pairs in superconductivity?

Cooper pairs are pairs of electrons that form at low temperatures due to attractive interactions mediated by phonons. These pairs behave like bosons, allowing them to move freely without resistance, which is what makes superconductivity possible.

What was the breakthrough discovery in 2020 related to superconductivity?

In 2020, the first room-temperature superconductor was synthesized, a carbonaceous sulfur hydride, which operates at 15°C (59°F), but it requires extremely high pressures, making it impractical for most applications at the moment.