Memory closes in on single photons

Mar 18, 2014
Memory closes in on single photons
An electron micrograph of the hollow-core fibre used in the team's experiment

(Phys.org) —In a world-first, an optical memory – a key component for quantum computers – has been created within a hollow-core optical fibre and shown to operate at the level of a single particle of light (a photon).

Single of light are the basic building blocks for quantum-enhanced computers and sensors. Unfortunately, creating exactly one photon is exceptionally challenging; most sources of single photons succeed in working only rarely and at random intervals. As a result, creating many single photons at the same instant becomes extremely unlikely, which is a major drawback for anyone hoping to use single photons to perform calculations. In theory, an optical memory could store single photons generated by individual sources, in effect briefly 'caching' them, so that many synchronised single photons could be produced at once. Such synchronised photons could be used to perform calculations many times faster than conventional computers.

Now an international team led by scientists at Oxford University has demonstrated in a new experiment that light pulses can be stored and retrieved using caesium atoms confined in the centre of a specially designed hollow-core optical fibre at room temperature. A report of the research is published in Nature Photonics.

'Unlike the standard fibre made with a glass core that might be buried under your street to carry your home broadband, these fibres can guide light in an empty core that can then be loaded with atoms to enhance their interaction with optical pulses,' said Michael Sprague of Oxford University's Department of Physics, lead author of the report.

'As the light and atoms are confined to a small area inside the fibre, the amount of energy needed to operate the memory is reduced by a factor of 200. We showed that we could store light with a noise level that was much less than that of a single photon, which points to the memory's promise for storing pulses of with interesting quantum properties,' he adds.

While caesium-based fibres are not compatible with the standard optical fibres used in telecommunications, it would be feasible to splice a hollow fibre optical memory into a conventional optical network. At the moment, the duration of the experimental is 30 nanoseconds, but the team believes it should be possible to increase this to 100 nanoseconds; not very long for some applications but long enough to create synchronised groups of single photons.

'So far nobody has managed to achieve the milestone of storing a true single photon in a room-temperature memory, but our work shows that memories that can get tens of synchronised single photons working together may only be a few years away,' said Michael Sprague.

Explore further: Scientists demonstrate switching effects caused by single photons

add to favorites email to friend print save as pdf

Related Stories

On-chip quantum buffer realized

Nov 13, 2013

Nippon Telegraph and Telephone Corp. has realized a quantum buffer integrated on an optical waveguide. The buffer is based on the "slow light effect", where the propagation speed of a pulsed light in a special ...

Into the quantum internet at the speed of light

Feb 04, 2013

Not only do optical fibers transmit information every day around the world at the speed of light, but they can also be harnessed for the transport of quantum information. In the current issue of Nature Ph ...

Optics: Statistics light the way

May 22, 2013

Millions of years of evolution have molded our eyes into highly sensitive optical detectors, surpassing even many man-made devices. Now, Leonid Krivitsky and his co-workers at the A*STAR Data Storage Institute ...

Quantum cryptography goes maintream

Dec 05, 2012

(Phys.org)—Researchers from Toshiba and the Department of Engineering have perfected a technique that offers a less expensive way to ensure the security of high-speed fibre-optic cables, protecting communication ...

Recommended for you

'Comb on a chip' powers new atomic clock design

2 hours ago

Researchers from the National Institute of Standards and Technology (NIST) and California Institute of Technology (Caltech) have demonstrated a new design for an atomic clock that is based on a chip-scale ...

Creating optical cables out of thin air

6 hours ago

Imagine being able to instantaneously run an optical cable or fiber to any point on earth, or even into space. That's what Howard Milchberg, professor of physics and electrical and computer engineering at ...

New material puts a twist in light

Jul 18, 2014

Scientists at The Australian National University (ANU) have uncovered the secret to twisting light at will. It is the latest step in the development of photonics, the faster, more compact and less carbon-hungry ...

Plasmon-enhanced Polarization-selective filter

Jul 17, 2014

As we all know, some optical devices can only work with a certain incident polarization direction. In this case, a polarizer is necessary to shift the polarization direction of linearly polarized light. A ...

User comments : 0