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: Pinpointing Qubits in a 3D Lattice
Quantum Information

Synopsis: Pinpointing Qubits in a 3D Lattice

Researchers manipulate atomic qubits individually in a three-dimensional optical lattice. Read More »

Viewpoint: Sending Quantum Messages Through Space
Quantum Information

Viewpoint: Sending Quantum Messages Through Space

Fragile photon states useful for quantum communication can be faithfully transmitted and distinguished over a link between an orbiting satellite and a telescope on Earth. Read More »

Synopsis: Good Vibrations
Quantum Information

Synopsis: Good Vibrations

With the assistance of lattice vibrations, quantum dots perform as single-photon emitters. Read More »

More Articles