Researchers closer to mastering the 'spookiness' of quantum mechanics

December 15, 2006
Researchers closer to mastering the 'spookiness' of quantum mechanics
One of the most famous code-breakers is the Colossus – used by the British during World War Two to break German signals intelligence. Credit: TopFoto/HIP.

Oxford theorists and their Cambridge collaborator have moved a step closer to creating a machine that would fully harness the deepest laws of physics, quantum mechanics. The machine, called a quantum computer, would have a range of potential uses – including code breaking. It could exactly simulate the behaviour of matter at the atomic scale, providing new insights to chemists and biologists.

Quantum dots – tiny nuggets of one material embedded inside another – could be the ideal building blocks for a quantum computer. However, in order to build such a device, it is necessary to create ‘entanglement’ between different dots, a phenomenon labelled ‘spooky’ by Einstein and the essential resource that would give a quantum computer its power.

In Physical Review Letters, Oxford student Avinash Kolli and his coauthors suggest a new way to create entanglement, by identifying two different stable states of a quantum dot (call them ‘A’ and ‘B’) and then targeting two such dots simultaneously with a laser.

The team discovered that, by watching the light emitted back from the dots, they would learn exactly one piece of information – namely, whether the two dots are in the same state as one another (AA or BB) or different states (AB or BA).

Crucially, this is the only piece of information that would come back. If the two dots are in different states, and if there really is no further information, then nature itself has absolutely no evidence indicating which is A and which is B. This would mean that the actual state of the two dots would be both AB and BA at the same time.

This strange state is a so-called quantum superposition. It is also an entanglement between the dots – the maximum possible degree of entanglement in fact.

Avinash Kolli said: ‘So, simply by illuminating the two dots with a laser and watching the light they emit, entanglement can be created – the elusive resource that will make quantum computation possible.’

A lot of work still needs to be done to flesh out this idea into a full blueprint for a quantum dot computer, but the predictions are testable with existing laboratory equipment. The team is now looking for experimentalists to collaborate on testing this proposal.

Source: University of Oxford

Explore further: Researchers use quantum dots to manipulate light

Related Stories

Researchers use quantum dots to manipulate light

August 30, 2016

Leiden physicists have manipulated light with large artificial atoms, so-called quantum dots. Before, this has only been accomplished with actual atoms. It is an important step toward light-based quantum technology. The study ...

JQI researchers create entangled photons from quantum dots

November 18, 2009

To exploit the quantum world to the fullest, a key commodity is entanglement—the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another. Now, physicists ...

Producing spin-entangled electrons

July 1, 2015

A team from the RIKEN Center for Emergent Matter Science, along with collaborators from several Japanese institutions, have successfully produced pairs of spin-entangled electrons and demonstrated, for the first time, that ...

Physicists Demonstrate Three-Color Entanglement

October 7, 2009

( -- For the first time, physicists have demonstrated the quantum entanglement of three light beams, all of different wavelengths. Entanglement of two light beams of different wavelengths has already been demonstrated, ...

Recommended for you

Researchers discover new rules for quasicrystals

October 25, 2016

Crystals are defined by their repeating, symmetrical patterns and long-range order. Unlike amorphous materials, in which atoms are randomly packed together, the atoms in a crystal are arranged in a predictable way. Quasicrystals ...

Making silicon-germanium core fibers a reality

October 25, 2016

Glass fibres do everything from connecting us to the internet to enabling keyhole surgery by delivering light through medical devices such as endoscopes. But as versatile as today's fiber optics are, scientists around the ...


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.