Neutral atoms as quantum computers: science fiction or reality

Quantum computers could be built using different physical modalities, with neutral atoms being one of them. Each modality has its pros and cons, and computers of different modalities are hardly directly comparable. The underpinning technology of neutral atom computers is both enthralling and seemingly unattainable. Recent advancements in this technology highlight the promise of neutral atoms as a powerful quantum computing platform, and several neutral-atom quantum computing companies pursue their construction, like Pasqal, ColdQuanta, Atom Computing, Planqc, M Squared and QuEra Computing.

QuEra recently unveiled an insightful white paper (https://arxiv.org/pdf/2306.11727.pdf), shedding light on the workings and applications of the 256-qubit Aquila neutral atom quantum computer.

Aquila operates at room temperature, utilising neutral Rb-87 atoms. These atoms are suspended and cooled to microkelvin temperatures by laser beams within a vacuum cell. Since these atoms are naturally quantum, they encode qubits in their electronic states. These states are manipulated with highly accurate laser pulses, allowing for the processing of quantum information, which can be subsequently detected.

In terms of its computation, atoms are arranged in a structure that mirrors the computational problem. Do not you think that the very concept of manoeuvring individual atoms and programming them might seem straight out of a science fiction narrative. Once arranged, computation is run through a sequence of laser pulses. Interestingly, Aquila represents an analog quantum computer. This denotes the use of continuous variables as opposed to discrete ones. Like most analogous devices, it is not immune to noise disturbances, which limits its computational capabilities.

For a more in-depth exploration of this subject, it's recommended to consult the original paper.