Synopsis: Early detection

Quick detection of photogenerated electrons in a quantum dot may lead to a better method to transfer quantum information between optical and electrical media.
Synopsis figure
Credit: Courtesy of A. Pioda et al.

In a quantum dot, the spin of an electron can act as a unit of quantum information. The photon is the ideal carrier of this information, which it can convey undisturbed over large distances. Researchers are therefore always on the lookout for robust means to transfer a quantum state between the storage (electron spin) and the messenger (photon).

In recent years, the quantum dot has come to be seen as a useful source of photogenerated electrons, which can be probed by so-called single-shot measurements using quantum point contacts. That said, such detection techniques are hampered by the need to complete the detection process before the electron spin flips thermally. Now, Alessandro Pioda, at the University of Tokyo, and coauthors in Japan report in a paper in Physical Review Letters that they may have dealt with this limitation in quantum dots formed from GaAs-based semiconductor heterostructures. By manipulating the electrical properties of the dot, and hence the tunneling time across the dot, they tune the time it takes to detect photogenerated electrons, on occasion making it shorter than the spin-flip time. The short timescale and tunability allows them to determine the spin direction of electrons generated by circularly polarized light. The authors hope that the ability to transfer the polarization of a photon to the spin of an electron will some day lead to a device to coherently transfer quantum information between an optical and an electrical medium—a solid-state quantum repeater. – Sami Mitra


Announcements

More Announcements »

Subject Areas

Quantum InformationOpticsMesoscopics

Previous Synopsis

Materials Science

Switched on ferroelectrics

Read More »

Next Synopsis

Astrophysics

Tuning in to gravity

Read More »

Related Articles

Focus: Strong Light Reflection from Few Atoms
Optics

Focus: Strong Light Reflection from Few Atoms

Up to 75% of light reflects from just 2000 atoms aligned along an optical fiber, an arrangement that could be useful in photonic circuits. Read More »

Synopsis: Controlling a Laser’s Phase
Optics

Synopsis: Controlling a Laser’s Phase

A compact scheme can directly modulate the phase of a laser without a bulky external modulator. Read More »

Focus: Chip Changes Photon Color While Preserving Quantumness
Photonics

Focus: Chip Changes Photon Color While Preserving Quantumness

A new device that can potentially be scaled up for quantum computing converts visible light to infrared light suitable for fiber-optic transmission without destroying the light’s quantum state. Read More »

More Articles