QNDLATTICE

Quantum control: manipulating and interfacing selected atoms in optical lattices with light

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 Obiettivo del progetto (Objective)

'The interdisciplinary boundary between the fields of quantum information science, condensed matter, and ultra-cold atomic physics is at the heart of the new field of quantum engineering and will play an important role for the enhancement of our understanding of strongly correlated materials. One of the most important tools in this domain is optical lattices, which are periodic optical potentials – artificial 'crystals' - created by counter-propagating laser beams. The dynamics of ultra-cold atoms in optical lattices is very similar to that found in solid state systems. In contrast to these, however, optical lattices have a high degree of purity, regularity, and tunability. They are therefore an ideal test bed for many condensed matter models such as those relevant for high-Tc-superconductivity and are a strong candidate for scalable quantum computation. The proposal will address two fundamental issues. Challenge 1: interface ultra-cold atoms in optical lattices with light. Although a non-destructive probe of the states in optical lattices would have great implications for the investigation of the rich many-body dynamics as well as for the field of quantum information processing it has never been implemented. In this project the experience of the applicant in non-destructive probing of room-temperature atomic gasses will be extended to optical lattices. Challenge 2: the manipulation and detection of single sites in an optical lattice represents a formidable technical challenge since the lattice spacing is of the order of 0.5um. In two hallmark experiments this resolution was achieved optically recently but the approach is very expensive and technically involved. Within this proposal a new way of achieving this resolution is introduced based on the interference of multiple coherent beams. Apart from technical simplicity it also offers enhanced sensitivity since the manipulation is controlled via the frequency – one of the most well-controlled properties in physics.'

Introduzione (Teaser)

It has only been about 10 years since pioneering experiments started on quantum gases trapped by laser beams. Now, scientists have pointed the way to use of a highly sensitive technique for manipulation of the spin of a single atom in such a system.

Descrizione progetto (Article)

An optical lattice is a periodic optical potential field (it has spatially dependent potential energy) created by the interference of counter-propagating laser beams. The dynamics of ultracold atoms in optical lattices are very much like those of solid-state systems, but with superior purity, regularity and tunability. This makes optical lattices a fertile test bed for the most exciting predictions in quantum engineering.

With EU support of the project 'Quantum control: Manipulating and interfacing selected atoms in optical lattices with light' (QNDLATTICE), scientists set out to merge the study of ultracold atoms in optical lattices with non-destructive (quantum non-demolition (QND)) measurements. QND measurements exploit the interaction of light with the atomic states in optical lattices. They enable one to observe a quantum system without altering it due to interference with the measurement apparatus itself.

Optical imaging of a single lattice site was achieved just prior to initiation of the reintegration grant, but the optical approach is expensive and technically quite complicated. During the reintegration phase, researchers focused on QND detection and manipulation in the optical lattice. In addition to being simpler, this technique is more sensitive because it exploits frequency that is relatively easy to control.

Given the lack of theoretical background merging the two distinct fields, the QNDLATTICE group developed the required simulation code. This enabled scientists to create and publish new architectures for scalable quantum computation, atomtronics and quantum control of many-body states using QND measurements. Development of a new laser system for QND imaging of ultracold atoms led to the first-ever probing of such atoms in optical lattices using the Faraday interaction (of light and a magnetic field).

The experimental setup and theoretical background for QND manipulation of individual sites in an optical lattice have been established. The objective is expected to be reached within a half-year of project-end. Access to an inexpensive and relatively simple experimental setup to manipulate the spin of a single atom will open a new window onto the quantum world. It will be an invaluable tool in the hands of the best and brightest.