Synopsis: ac/dc Spin Control

Manganese defects in zinc oxide have been identified as a class of electrically controllable qubits.
Synopsis figure
R. E. George et al., Phys. Rev. Lett. (2013)

Electron spins of individual atoms are natural candidates for realizing quantum bits (qubits) in quantum computing schemes. Controlling such spins with electric rather than magnetic fields is particularly advantageous, since electric fields can be applied at length scales as short as tens of nanometers, the separation between qubits in a device. However, not all spins are equally amenable to electric control. Writing in Physical Review Letters, Richard George and collaborators at the University of Oxford, UK, have identified a class of spin systems that can be easily manipulated with electric fields.

The team studied high-spin paramagnetic manganese defects that have a significant axial anisotropy in zinc oxide. By applying dc electric field pulses, the authors modulate the manganese ion anisotropy to generate phase shifts of the spin coherence. This means that they can, by electrical means, tune spins in and out of resonance with other spins for spintronic applications. Further, using ac microwave fields, they can control spin populations by driving resonant electric dipole transitions between different spin states, which could be used for switching applications.

For both the dc and ac case, the response is fast, which allows them to carry out about a million single-qubit operations within the spin coherence lifetime (on the order of milliseconds at low temperatures). Since the results should be extendable to any high-spin defect in a polar material, next steps may involve the use of iron defects (possibly with a larger spin-electric coupling than manganese) or a different substrate such as strontium titanate, whose ferroelectric properties would open up further possibilities for electric control. – Daniel Ucko


Features

More Features »

Announcements

More Announcements »

Subject Areas

Quantum InformationSpintronics

Previous Synopsis

Next Synopsis

Biological Physics

Through the Eye of the Needle

Read More »

Related Articles

Focus: Germanium Revived from the Spintronics Graveyard
Spintronics

Focus: Germanium Revived from the Spintronics Graveyard

Germanium produces a surprisingly large separation of electron spins in response to electric current—good news for spin-based devices, since germanium is highly compatible with silicon. Read More »

Viewpoint: Photonic Hat Trick
Optics

Viewpoint: Photonic Hat Trick

Two independent groups have provided the first experimental demonstration of genuine three-photon interference. Read More »

Viewpoint: Microwave Quantum States Beat the Heat
Quantum Information

Viewpoint: Microwave Quantum States Beat the Heat

A new quantum communication protocol is robust in the presence of thermal noise, paving the way for all-microwave quantum networks. Read More »

More Articles