Summary of Key Points
This news article focuses on three seemingly unrelated items—liquid helium, magnets, and LED bulbs—and reveals their common capability to achieve extremely low temperatures close to absolute zero (-273.15°C). It also discusses why such cooling technology is essential for quantum computers and whether ordinary computers can benefit from these methods.
Detailed Analysis
1. How do liquid helium, magnets, and LEDs reduce temperature to near absolute zero?
Although the cooling principles of these three substances are different, they all manage to reach “cosmically cold” temperatures:
- Liquid helium: It cools by evaporating and absorbing heat. With a boiling point of only -268.9°C, liquid helium absorbs a large amount of heat as it evaporates from a container, significantly lowering the surrounding temperature. This process is millions of times more effective than the cooling effect of sweat on the skin during summer.
- Magnets: They use “adiabatic demagnetization”. Imagine a strong magnet holding a collection of iron particles; the particles are arranged in an orderly manner (low energy state). When the magnet is removed, the particles scatter and release energy. If this process occurs in isolation (adiabatically), the temperature drops dramatically. Scientists use special materials instead of iron particles to achieve temperatures below one millionth of a degree.
- LED bulbs: They utilize “electrical refrigeration”. While regular LEDs generate heat when emitting light, certain special LED types (e.g., those made with gallium arsenide) can transfer some electrons to a lower energy state while releasing surrounding heat, effectively cooling the area to around -200°C.
2. Why are quantum computers dependent on near-absolute zero temperatures?
The “core components” of quantum computers, known as qubits, are extremely fragile:
- Qubits function in a quantum superposition state (being both 0 and 1 simultaneously), but this state is very susceptible to interference. Even slight temperature increases can cause the particles to collide and disrupt the superposition, a phenomenon called “decoherence”.
- At near-absolute zero temperatures, particle motion nearly comes to a halt, allowing qubits to remain in their superposed state without interference. This is similar to how you can concentrate on reading in a quiet library; quantum bits work more stably at such low temperatures.
3. Are these cooling technologies useful for ordinary computers?
The answer is both unnecessary and impractical:
- High cost: Liquid helium requires specialized storage containers, and one liter costs several hundred dollars. Magnet-based cooling systems are larger than refrigerators, and the materials used in special LEDs are also expensive.
- Complex maintenance: Ordinary computers have sufficient cooling capabilities (e.g., fans or water cooling) for temperatures within a few dozen degrees Celsius, so there’s no need to invest in these high-tech solutions.
- Excessive cooling may be harmful: Chips in ordinary computers operate perfectly at 60–80°C; lowering the temperature too much could cause damage, such as material shrinkage and cracking.
4. What other applications do extreme low-temperature cooling technologies have?
These technologies are not limited to quantum computers:
- Medicine: MRI machines use superconducting magnets that require liquid helium to maintain their superconducting state (zero electrical resistance), enabling strong magnetic fields.
- Astronomy: Detectors in telescopes (e.g., infrared detectors) need extreme low temperatures to minimize thermal noise and capture clearer cosmic signals.
- Materials science: Researchers study high-temperature superconductors at low temperatures to test their properties.
- Biological research: Some biological samples (e.g., stem cells) must be preserved at near-absolute zero to prevent damage.
In Conclusion
Extreme low-temperature cooling is crucial for quantum computers but is often overkill for ordinary computers. Although liquid helium, magnets, and LEDs have different cooling mechanisms, they each play a vital role in advancing quantum technology as well as in various other fields such as medicine and astronomy. Next time you encounter these terms, remember that they’re more than just everyday items—they represent cutting-edge cooling technologies!