Superconductors can be forced to group electrons into fours instead of the usual pairs, creating a new state of matter.
April 23, 2026
Original Paper
Nonequilibrium Cooper quartet generation in superconducting devices
arXiv · 2604.16647
The Takeaway
Superconductivity depends on electrons pairing up into Cooper pairs to flow without resistance. This new proposal uses a double-quantum-dot system to isolate Cooper quartets made of four correlated electrons. These quartets are generated by driving the system out of its normal equilibrium state. Finding stable groups of four electrons would shatter the long-held rule that superconductivity is strictly a two-particle phenomenon. This discovery could lead to a new class of electronic devices that are even more stable than current quantum computers. It opens a door to exploring entirely new phases of correlated matter.
From the abstract
Cooper quartets are aggregates of four electrons that generalize the concept of Cooper pairs, and their study can unfold unexplored perspectives in correlated matter and many-body physics. We propose a method to isolate them in a double-quantum-dot system coupled to conventional superconducting and normal leads. By driving the system out of equilibrium, we show that a resonance between the vacuum $|0\rangle$ and the four-electron state $|4e\rangle$ emerges in the high bias voltage regime, which