Synopsis: Floating Gates

Semiconductor quantum dots connected by floating metallic gates point the way to a scalable quantum computer.
Synopsis figure
L. Trifunovic et al., Phys. Rev. X (2012)

The spin of an electron can act as a qubit—the on/off switch that is the building block of a quantum computer. In 1998, in a paper in Physical Review A, Daniel Loss and David DiVincenzo presented a scenario for implementing spin qubits in semiconductor quantum dots. Considerable experimental progress has since been made, evidenced in particular by longer decoherence times—the time after which the spin’s phase irreversibly changes—that are now around 270 microseconds, an improvement of 7 orders of magnitude.

One barrier to building a scalable quantum computer remains: how to accommodate enough qubits in an arrangement without overrunning it with wires and metallic gates. In a paper in Physical Review X, Luka Trifunovic at the University of Basel, Switzerland, and his coauthors propose a setup that would use a two-dimensional array of quantum dots to address this challenge by spacing dots far enough apart to provide sufficient gaps for wirings and gates, while bridging the distance with a mechanism to enable long-range interdot tunnel coupling of sufficient strength.

Central to the proposal is an ingenious architecture that would connect dots in a two-dimensional electron gas with floating metallic gates (classical objects), leading to a robust entanglement (a quantum phenomenon) between spin qubits that are some distance apart. The authors claim that the technology to build this configuration, a seemingly substantive step towards a full-scale quantum computer, already exists. – Sami Mitra


Announcements

More Announcements »

Subject Areas

Quantum Information

Previous Synopsis

Quantum Information

Neither Here Nor There

Read More »

Next Synopsis

Quantum Information

One Photon Good, Two Better

Read More »

Related Articles

Synopsis: One-Way Quantumness
Quantum Physics

Synopsis: One-Way Quantumness

Experiments provide evidence for one-way quantum steering—an effect by which distant entangled systems can influence one another in a directional way. Read More »

Viewpoint: Quantum Hoverboards on Superconducting Circuits
Quantum Physics

Viewpoint: Quantum Hoverboards on Superconducting Circuits

A new quantum device uses a superconducting circuit to monitor a 2D gas of electrons floating on the surface of superfluid helium. Read More »

Synopsis: Even-Handed Control of Quantum Dot Qubits
Quantum Information

Synopsis: Even-Handed Control of Quantum Dot Qubits

A new way to control the coupling of spins between adjacent quantum dots produces qubits that are less susceptible to electronic noise. Read More »

More Articles