# The Quantum Abacus: Analog Computing using Surface Rydberg States

## TL;DR

This paper proposes a novel quantum computing approach called the Quantum Abacus, which uses surface Rydberg states confined by a cryogenic substrate for potentially more stable and scalable quantum computation.

## Contribution

It introduces a new method of using surface Rydberg states confined by a cryogenic substrate for quantum computing, enhancing stability and coherence times.

## Key findings

- Rydberg atoms have millisecond-range lifetimes.
- Surface confinement can improve quantum coherence.
- A conceptual design of the quantum abacus is presented.

## Abstract

Recently, Rydberg atoms appeared as a viable alternative to the quantum gates built on atomic or molecular ions. The lifetimes of the circular Rydberg states can be in the millisecond range. That prevents inherent metastability of the Rydberg atoms to influence computation at the typical decoherence times, which are now being achieved in the range of 1 ms. The paper proposes to use a pinning potential of an image charge on a cryogenic substrate (liquid He, in particular) to confine large densities of Rydberg atoms to dielectric surfaces. The substrate can also act as a natural cooler medium. A design of the computer (quantum abacus) based on these ideas is briefly sketched in the paper.

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Source: https://tomesphere.com/paper/1802.08303