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Related Concept Videos

Entropy02:39

Entropy

Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...
Entropy01:18

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The first law of thermodynamics is quantitatively formulated via an equation relating the internal energy of a system, the heat exchanged by it, and the work done on it. A quantitative formulation of the second law of thermodynamics leads to defining a state function, the entropy.
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Entropy, a measure of disorder in a system, changes during phase transitions like freezing or boiling. At the transition temperature Ttrs, where two phases are in equilibrium, the phase transition is a reversible process. The entropy change can be calculated from a substance's enthalpy of transition using the equation ΔStrs = ΔtrsH /Ttrs.When a perfect gas expands isothermally from one volume to another, entropy increases logarithmically with volume. Conversely, isothermal compression results...
Superconductor01:24

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A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a superconductor. In 1911, Heike Kamerlingh Onnes of Leiden University, a Dutch physicist, observed a relation between the temperature and the resistance of the element mercury. The mercury sample was then cooled in liquid helium to study the linear dependence of resistance on temperature. It was observed that, as the temperature decreased, the...
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Atomic Nuclei: Nuclear Spin State Population Distribution

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Atomic Spectroscopy: Effects of Temperature01:27

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Atomization, converting samples into gas-phase atoms and ions, is essential for atomic spectroscopy. The flame temperature required for atomization affects the efficiency of the atomic spectroscopic methods by increasing the atomization efficiency and the relative population of the excited and ground states.
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Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
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Increasing quantum degeneracy by heating a superfluid.

D J Papoular1, G Ferrari, L P Pitaevskii

  • 1INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.

Physical Review Letters
|September 26, 2012
PubMed
Summary
This summary is machine-generated.

A novel thermomechanical effect in superfluids causes atoms to flow from hotter to colder compartments, increasing quantum degeneracy. This phenomenon occurs in superfluid helium at low temperatures and in dilute quantum gases below critical temperature.

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Area of Science:

  • Thermodynamics
  • Quantum Mechanics
  • Condensed Matter Physics

Background:

  • Superfluidity is a state of matter characterized by frictionless flow.
  • The fountain effect in superfluid helium demonstrates flow from colder to hotter regions.
  • Understanding thermomechanical effects is crucial for quantum gas and superfluid research.

Purpose of the Study:

  • To investigate a novel thermomechanical effect in a two-compartment superfluid system.
  • To analyze the direction of superfluid flow under thermal gradients.
  • To explore the impact on quantum degeneracy.

Main Methods:

  • Theoretical analysis of a uniform superfluid in two connected compartments.
  • Consideration of thermal gradients and superleak dynamics.
  • Examination of quantum degeneracy changes.

Main Results:

  • Superfluid atoms flow from hotter to colder compartments under specific conditions, reversing the fountain effect.
  • This flow leads to increased quantum degeneracy in the colder compartment.
  • The effect is observed in superfluid helium at low temperatures and dilute quantum gases below T(c).

Conclusions:

  • A new thermomechanical effect, opposite to the fountain effect, has been identified in superfluids.
  • This effect provides a mechanism to enhance quantum degeneracy.
  • The findings are relevant for both superfluid helium and dilute quantum gases.