Cooper-Pair Splitting on Demand

Physics 17, s18
A proposed device can repeatedly grab pairs of electrons from a superconductor and separate them while preserving their entangled state.
F. Brange et al. [1]

Many quantum technologies rely on separating and interrogating entangled particles. Superconductors already come with a supply of paired-up entangled electrons—the Cooper pairs that give these materials their transport properties. However, extracting and separating them on demand is a challenge. Now theorist Christian Flindt of Aalto University in Finland and his collaborators have shown that the splitting of Cooper pairs can be accurately controlled using time-dependent voltages [1].

A Cooper pair comprises two electrons whose spins are entangled and point in opposite directions. In existing Cooper-pair splitters, these electrons, once split, tunnel into separate quantum dots, or artificial atoms. However, this process has proved noisy, uncontrollable, and therefore unsuitable for most applications. Flindt and his collaborators propose a way to make the splitting of Cooper pairs much more reliable.

The key to the operation of their proposed device lies in the multitasking of its electrodes, which define two quantum dots, one on each side of a superconducting strip. These electrodes draw Cooper pairs to the tip of the superconductor and separate them. They also set the energy levels in the two quantum dots so that each dot can readily accept a separated electron before passing it on through a nanowire. Importantly, the voltage applied to the electrodes on one side varies periodically in time in such a way that exactly two Cooper pairs are split and emitted in each period of the drive.

Using realistic values for materials and components, Flindt and his collaborators estimate that their on-demand Cooper-pair splitter could operate in the gigahertz range. They also speculate that yoking several of them together could form the basis of a quantum computer than runs on entangled electrons.

–Charles Day

Charles Day is a Senior Editor for Physics Magazine.


  1. F. Brange et al., “Adiabatic Cooper pair splitter,” Phys. Rev. B 109, L081402 (2024).

Subject Areas

Condensed Matter PhysicsQuantum Information

Related Articles

A General Equation of State for a Quantum Simulator
Condensed Matter Physics

A General Equation of State for a Quantum Simulator

Researchers have characterized the thermodynamic properties of a model that uses cold atoms to simulate condensed-matter phenomena. Read More »

Harness Strain to Harvest Solar Energy
Condensed Matter Physics

Harness Strain to Harvest Solar Energy

The engineering of structural deformations in light-sensitive semiconductors can boost the efficiency of solar cells. Read More »

Constraining Many-Body Localization
Statistical Physics

Constraining Many-Body Localization

Theoretical work sheds light on why some many-body quantum systems get locally stuck and fail to reach thermal equilibrium—a phenomenon known as many-body localization. Read More »

More Articles