# Synopsis: Spins control spins

Nuclear spins may enable enhanced control of electron spins in quantum information devices.

A promising approach to the development of devices that process quantum information depends on the manipulation and control of individual electron spins in semiconductor quantum dots. A particular challenge is that the interaction of electron spins with their environment, particularly with nuclear spins in the semiconductor, can lead to decoherence. If the nuclear spins are adequately controlled, however, they can become an asset for manipulating an electron-spin qubit.

In a theoretical article recently published in Physical Review Letters, Michael Gullans and coauthors from Harvard University, MIT, and the University of Maryland at College Park, all in the US, study how the spins of two electrons in a pair of electrically gated $\text{GaAs}$ quantum dots interact with nuclear spins of the $\text{GaAs}$. As electrons are pumped through the dots, nuclei can be polarized differentially in the two dots by the process of dynamic nuclear polarization. The authors identify three regimes relevant to long-term behavior of the nuclei, each with specific behaviors for the difference between the dot’s Overhauser fields—the effective magnetic fields caused by the nuclear spins. These techniques could allow the nuclei to be used for fast qubit manipulation and for long-lived quantum memory. – Sami Mitra

### Announcements

More Announcements »

## Previous Synopsis

Particles and Fields

## Next Synopsis

Biological Physics

## Related Articles

Quantum Information

### Viewpoint: Hiding a Quantum Cache in Diamonds

Entanglement purification, a vital enabler for practical quantum networks, has been shown to be feasible with secluded nuclear memories in diamond. Read More »

Optics

### Viewpoint: Classical Simulation of Quantum Systems?

Richard Feynman suggested that it takes a quantum computer to simulate large quantum systems, but a new study shows that a classical computer can work when the system has loss and noise. Read More »

Quantum Physics

### Focus: Landmarks—Correcting Quantum Computer Errors

In the mid-1990s, researchers proposed methods to preserve the integrity of quantum bits—techniques that may become the key to practical quantum computing on a large scale. Read More »