[ad_1]
Researchers at the CNRS Higher Institute of Optics and Paris-Saclay University in France used a laser technique to rearrange cold atoms one by one in fully-ordered 3D patterns. The networks, which contain up to 72 neutral atoms contained in an optical trap, could be used to simulate multi-body complex systems in physics.
While conventional computers store and process information as "bits" that can have two states – "0" or "1" – a quantum computer exploits the ability of quantum particles to "overlay" two states or more. Such a device could in principle outperform a conventional computer to solve complex computer problems, such as taking large numbers into account or simulating the interactions between many fundamental particles.
In recent years, researchers have attempted to adapt a number of quantum methods and technologies, such as superconducting qubits and trapped ions, to create quantum computers in the real world, and many advances have been made in this area. A team led by Antoine Browaeys of the Charles Fabry Laboratory reports on a new technology based on trapped neutral atoms.
Neutral atoms are promising for quantum computing because the qubits derived from them are extremely well isolated from ambient noise, so their coded state remains intact. They can also be finely controlled using optical traps (or forceps) and scaled for a large number of qubits. Optical tweezers work by trapping tiny objects near the focus of a laser beam and the technique can pick up these objects and move them to another location using only light forces.
Controlled interactions needed
Quantum computing operations require controlled interactions between atoms. Thus, computers based on quasits of neutral atoms will first have to be arranged accurately in a specific model. Such models have proved difficult to do so far, in particular by using qubits of neutral atoms. Although the researchers have managed to organize these atoms in 1D and 2D, they will have to be able to stack them in 3D as the number of qubits will reach the hundred and to create structures that are not possible in 2D .
In their experiments, Browaeys and colleagues used a spatial light modulator to generate microtaches (arranged, for example, in two-layer graphene structures or pyrochlore arrays) separated by a few microns. "We initially loaded and half filled these traps with cold rubidium atoms," says lead author Daniel Barredo. "We then use a combination of acousto-optical deflectors and electrically tunable lenses to create moving optical tweezers that can" pluck "and transport atoms, one at a time, from" reservoir "traps to empty berry sites.
The technique allows researchers to sort out disordered atom networks into a single sand, creating faultless 3D qubit arrays in a variety of different patterns. This also allows them to overcome one of the major problems encountered when working with ultra-cold atoms. Normally, each optical trap is simply randomly loaded into a matrix and therefore only has a 50% probability of being filled with one atom at a time, but for applications, a fully charged matrix flawless is ideal. This is a case in which each trap has a 100% probability of containing a single atom.
Browaeys and his colleagues measured the complete occupation of the matrix sites by illuminating the system with light and observing the fluorescence of the rubidium atoms using a CCD camera (see image ).
Promising platform
They did not stop there though: they then managed to design interactions between two individual qubits in one of the arrays by exciting atoms in so-called Rydberg states. These produce atomic electric dipoles that allow the qubits to "understand each other" through dipole-dipole interactions.
"Neutral arrays excited by Rydberg states have recently emerged as a very promising platform for quantum simulations of large physical systems," says Barredo. World of Physics. "Indeed, recent work has shown that Rydberg's interactions between small neutral atom qubit systems can be used to perform quantum logic operations. Until now, the largest quantum simulations that can be performed with these systems involved about 50 qubits in 1D and 2D geometries. Access to the third dimension, as we realized in this work, allows not only to increase the size of these qubits (up to 72 atoms in our case), but also to simulate phenomena and more complex physical materials.
Researchers, reporting their work in Nature 10.1038 / s41586-018-0450-2, they are now looking at using their fully reconfigurable 3D arrays of individually controlled atoms to study, for example, the role of "frustration" in quantum systems or how topology can give place to new phases of the material. "At the same time, we will try to increase the size of our larger network, which until now has been limited only by the life of the atoms in the microchips (about 10 seconds)," says Barredo.
Source link
