Laser control helps store light

A method for storing and "repeating" light pulses was discovered by a team of researchers from the Australian National University (ANU), which allows laser light to act as a soft optical memory. flexible and capable of supporting the expansion of the scope of quantum information systems. This research result is an ideal application for creating nanocrystals with high uniformity.

Technologies such as quantum cryptography are being developed to send confidential information encrypted into a beam of light based on the properties of quantum physics. However, at present these systems cannot extend beyond the distance of 50-100 km, because beyond that range, much information will be lost.

But the team from the Center for Quantum Optics - ARC Atom at ANU University demonstrated how photons can be used to create a quantum memory device, that is, Light pulses can be retained, stored and then released as needed. Thus, the device will be an important part, which can extend the scope of secure quantum communication.

Dr. Ben Buchler, a member of the research team explained, light can be a great means to convey information quickly, but does not maintain at a certain location. This is the problem of optical memory, how to keep the information encrypted in one place so you can access it again later. The method that scientists have discovered is to absorb light in a cloud of atoms, which in turn can release light at will.

In his experiments, Associate Professor Mahdi Hosseini and his research team at ANU have developed a new way in which pulses of laser light are absorbed into a cloud of atoms surrounding a coil of electricity. The coils create a magnetic field that changes the frequency of the atoms. After absorbing the laser pulses, the rotational speed of all atoms starts differently, depending on its frequency. If the magnetic field is reversed, the atoms will directly change and rotate in different directions. When returning to its original state, these atoms will absorb light, and laser pulses are released.

However, Dr. Buchler emphasized that they want to have further steps. They can stretch, compress or split pulses as they gain more knowledge and better understanding of the mechanism of action. Scientists can recall the order of pulses, like a random access memory in a computer, that can recall electronic information in any order. To accomplish all this, the team used to combine a second control laser beam to switch the magnetic field, having a precise and quick selection when recalling any one of the pulses. storage.

This study, published in Nature, offers a way to store laser pulses with an initial efficiency of up to 40%. This research was carried out by Dr. Ben Buchler, Ben Sparkes, Gabriel Heter, Mahdi Hosseini and scientists from ANU University and Otago University.