Cooper Pairs: Non-Ideal Gas Behavior & BEC Comparisons

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Discussion Overview

The discussion revolves around the behavior of Cooper pairs in relation to non-ideal gas behavior and comparisons with Bose-Einstein condensates (BECs), particularly in the context of Josephson junctions (JJs). Participants explore theoretical aspects and analogies between Cooper pairs and BECs, as well as the implications of repulsive interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that repulsive interactions are a key attribute of Cooper pairs that prevent them from behaving like an ideal gas and questions if other attributes contribute to this non-ideal behavior.
  • Another participant suggests that a condensate is not necessary for forming a Josephson junction and mentions that the Josephson equations can be derived without a microscopic model, indicating the generality of the Josephson effect.
  • A different participant expresses interest in relating the two islands of a Josephson junction to two BECs of Cooper pairs, particularly under conditions where the charging energy is significantly larger than the Josephson coupling energy, while noting challenges in understanding this analogy.
  • One participant acknowledges the previous reply, indicating engagement with the discussion.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are differing views on the necessity of a condensate for Josephson junctions and the relationship between Cooper pairs and BECs. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some limitations include the potential dependence on specific definitions of terms like "ideal gas" and "BEC," as well as the unresolved nature of the analogy between Josephson junctions and BECs of Cooper pairs.

petr1243
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Repulsive interactions are an attribute of Cooper Pairs, which mean that Cooper Pairs don't behave like an ideal gas . Are these the only attributes that prevent Cooper pairs to behave like an "ideal" boson? How could we show that the two superconductors of a JJ behave just like two BEC's?
 
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I am not sure I understand the questions. AFAIK you do not need a condensate in order to form a JJ (I presume you mean a Josephson junction). You do not even need a microsopic model for what is going on in the two banks in ordet to derive the Josephson equations (which is fortunate since this means that we can model high-Tc junctions).
There is a very nice (and simple) derivation of the equations in the Feynman lectures. I like it because it shows that the Josephson effect is very "general" (at least once the equations have been generalized to non-sinusoidal CPRs, Feynman's approach can be easily modified to cover this).
Hence, it is not surprising that it can be created using so many different systems including two BEC.

Alexander Golubov wrote a very nice review of the Josephson effects a few years ago (which includes unconventional current-phase relations); you should be able to find it using Google schoolar (I don't remember the title but I do have it on my computer at work).
 
i appreciate the above reply
 
I'm not interested in the derivations of the well know ac and dc josephson equations. However, I am interested in trying to relate the two islands of a josephson junction with two BE condensates of Cooper pairs when the charging energy is sufficiently much larger than the Josephson coupling energy. I'm just having a difficult time in understanding this analogy. I understand that quasiparticle tunneling is minimal, when we have strong repulsive interactions between the two electrons. Any help would be well appreciated.
 
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