Quantum gates and interfaces with atomic Rydberg interactions

Bindiya Arora, Safronova, Charles W. Clark

Ayelet Hasson, Gal Dekel, Ehud Shahar +2 more

Hybrid quantum systems combining neutral atoms and trapped ions offer the prospect of integrating the scalability of atom arrays with the high-fidelity control available in trapped-ion platforms. Here we propose and analyze a quantum interface between individually trapped neutral atoms and a trapped-ion crystal. In our scheme, a neutral 88Sr atom trapped in optical tweezers interacts with a small 88Sr+ ion crystal, and by exciting the atom to a Rydberg state, the atom-ion polarization interaction is strongly enhanced, resulting in a state-dependent modification of the ions' collective motional modes. We show that this shift enables conditional control of a MS gate, allowing the neutral atom to act as a control qubit for an entangling operation between two ions. We investigate the feasibility of the scheme by analyzing Rydberg trapping in the combined optical tweezers and Paul trap potentials, identifying negative-polarizability Rydberg states as particularly favorable for stable confinement. We further evaluate the relevant trapping conditions, Rydberg lifetimes, and coherence requirements, and show that the proposed interface is compatible with realistic experimental parameters. These results establish a practical route toward deterministic atom-ion hybrid quantum gates and quantum interfaces.

Pei‐Yao Song, F.-Q. Guo, Jin‐Lei Wu +1 more

Abstract Hybrid quantum systems provide versatile physical properties that could be qualified for high‐fidelity quantum information storage, distribution, and processing in a quantum network. This work proposes to synthesize a hybrid generalized Jaynes‐Cummings (JC) model among two mircowave (MW) cavities and a Rydberg atom, where the Rydberg transition occurs by simultaneously absorbing or emitting two MW photons distributed in different cavities. Based on this synthesized Rydberg two‐mode two‐photon JC (TMTP‐JC) model, a hybrid MW‐MW‐atom Toffoli gate is constructed with the atomic qubit encoded on two stable ground states. Furthermore, the Rydberg atom is considered as an interface in an MW‐optical quantum network and a scheme is demonstrated for generating a three‐body photonic entangled state among the two MW cavities and an optical cavity, assisted by the synthesized Rydberg TMTP‐JC interaction. The proposed setup provides a Rydberg‐state–mediated interface for constructing MW‐MW‐atom three‐qubit gates and entangling three‐body MW‐MW‐optical photons, which may bridge the gap for modular, scalable, and cross‐platform quantum networks.

David Petrosyan

R. J. C. Spreeuw, Vanessa Y. F. Leung, Atreju Tauschinsky +1 more

Francisco D. Santillan, Andreas Hanke

The interaction between atoms and a quantized radiation field is fundamentally important in quantum optics and quantum information science. Due to their unusual properties, Rydberg atoms are promising building blocks for two-qubit gates and atom-light quantum interfaces, exploiting the Rydberg blockade interaction which prevents two atoms at close distance ( < 10 μ m ) from being simultaneously excited to Rydberg states. Recently, this effect was used to engineer quantum processors based on arrays of interacting Rydberg atoms illuminated by Raman lasers. Motivated by these experiments, we extend the Jaynes–Cummings model to study the interaction between two Rydberg atoms interacting by the Rydberg blockade and a quantized radiation field. We consider both number (Fock) states of the field and single-mode quantum coherent states. In particular, we discuss different types of entanglements between various components of the total system consisting of the two Rydberg-interacting atoms and coherent states of the field, and show that the behavior is significantly different compared to a system with non-interacting atoms corresponding to the two-atom Tavis-Cummings model. Our results are relevant in view of atom-light quantum interfaces as components for future long-distance quantum communication.