Cryogenic Neutral Atom Arrays for Quantum Processors

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

In less than a century, quantum physics has grown from an interesting puzzle, to a striking reality, to a source of revolutionary computational ideas. A computer based upon the power of quantum physics will be able to solve certain tasks at rates unmatched by classical computers, and measurement tasks will benefit from the ability to harness correlations between quantum particles. However, physicists and engineers face seemingly impossible tasks in assembling these devices. Fully isolating thousands of single quantum particles and at the same time introducing ways for them to interact is very difficult. The fragility of entanglement means that the disturbance of just one of those particles can be a catastrophic event. The goal of this project is to devise techniques to advance isolation and control of neutral atoms in ‘tweezers’ made from focused laser beams, a potential new platform for realizing many interacting quantum particles. By operating at temperatures achieved with liquid cryogens, 4 degrees above absolute zero, the atoms can held in traps for longer times, and highly-excited atomic states, known as Rydberg states, can have longer lifetimes. The proposed work will study quantum processing with Rydberg atoms focusing on gate fidelity advances achievable with these advances. The work will encompass graduate student training and impact on undergraduate education. The bottom-up assembly of arrays of single atoms, their individual control, and entangling mechanism such as Rydberg excitation have enabled new perspectives on scalable and addressable sets of neutral atoms for quantum computing. However, advances could soon saturate due to limitations in multiple aspects of quantum coherence. Neutral atom platforms should aspire to the same, and in some areas even better, control than is currently afforded by trapped ions. One unique path for improvement in a few of the key metrics is embedding the neutral atoms in a cryogenic system, where atoms can potentially be stored in microscopic traps for hours and blackbody radiation is defined by a low temperature environment. A new cryogenic apparatus has been developed based on a closed-cycle cryostat that retains single-atom control of 87Rb through optical tweezers. The proposed work will deploy and study this system for quantum processing with Rydberg atoms, focusing on two-qubit gate fidelity advances utilizing the cryogenic apparatus and through harnessing single atom cooling and magic trapping conditions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.