Improving electron control

Dec 05, 2013
An artist's impression of the experiment: Individual electrons (blue) will cross a potential barrier (foreground) if they still have enough energy, and the barrier is low enough, when they arrive

In principle, the strange features of quantum mechanics can be accessed using single electrons as carriers of quantum information. However, while electrons can be captured in solid-state electrostatic traps, it is difficult to control them or to discover what happens to them once they are released.

Now, research from the National Physical Laboratory (NPL) has revealed key details about how are ejected from a trap and demonstrated that the electrons can actually be detected relatively far from the source.

The new research, published in Physical Review Letters, places an electrically-controlled barrier into the path of the electrons ejected from the trap. The strength of the barrier can be varied and the electrons will only cross the barrier if they retain enough energy to do so.

Using this technique, NPL's Quantum Detection Group found that the electrons travel for many micrometres before they lose energy - a large distance when considering the small scale of the experiment.

NPL's Jonathan Fletcher, who worked on the project, said:

"At a crude level, it's like a ballistics experiment where you find out how much energy a bullet has by firing it at a target and seeing whether or not it penetrates. The difference is that in this case the whole experiment is tiny. Our 'catapult' is a quantum dot, the projectile is a single electron, and the 'target' is an electrically-controlled barrier whose strength we can vary."

By rapidly turning the barrier on and off at different times the scientists could also probe the electrons with very precise time resolution. This technique works because the electrons are actually forced out of the pump by a trigger signal, against which the blocking detector can be synchronised.

The flexibility and resolution of this system was revealed by a new trick which emerged during the measurements. Two electrons ejected from a doubly loaded trap could actually be split into different paths using either the small energy or ejection time difference.

The measurement techniques described in this research could be used to guide the design of electron pumps or as part of a future method of transport using electrons.

Explore further: New filter could advance terahertz data transmission

More information: J. D. Fletcher, P. See, H. Howe, M. Pepper, S. P. Giblin, J. P. Griffiths, G. A. C. Jones, I. Farrer, D. A. Ritchie, T. J. B. M. Janssen, and M. Kataoka, "Clock-Controlled Emission of Single-Electron Wave Packets in a Solid-State Circuit." Phys. Rev. Lett. 111, 216807 (2013) DOI: 10.1103/PhysRevLett.111.216807

Physics Focus article: physics.aps.org/articles/v6/127

add to favorites email to friend print save as pdf

Related Stories

New nanodevice builds electricity from tiny pieces

Jul 06, 2012

(Phys.org) -- A team of scientists at the National Physical Laboratory (NPL) and University of Cambridge has made a significant advance in using nano-devices to create accurate electrical currents. Electrical ...

Quantum information motion control is now improved

Apr 03, 2012

Physicists have recently devised a new method for handling the effect of the interplay between vibrations and electrons on electronic transport. Their paper is about to be published in the European Physical Journal B. This s ...

What can happen when graphene meets a semiconductor

Nov 21, 2013

For all the promise of graphene as a material for next-generation electronics and quantum computing, scientists still don't know enough about this high-performance conductor to effectively control an electric ...

Recommended for you

New filter could advance terahertz data transmission

Feb 27, 2015

University of Utah engineers have discovered a new approach for designing filters capable of separating different frequencies in the terahertz spectrum, the next generation of communications bandwidth that ...

The super-resolution revolution

Feb 27, 2015

Cambridge scientists are part of a resolution revolution. Building powerful instruments that shatter the physical limits of optical microscopy, they are beginning to watch molecular processes as they happen, ...

A new X-ray microscope for nanoscale imaging

Feb 27, 2015

Delivering the capability to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright ...

Top-precision optical atomic clock starts ticking

Feb 26, 2015

A state-of-the-art optical atomic clock, collaboratively developed by scientists from the University of Warsaw, Jagiellonian University, and Nicolaus Copernicus University, is now "ticking away" at the National ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.