由腔體介導的原子量子位元的新型穿行糾纏邏輯閘

Abstract

量子計算以指數級速度超越經典計算，可能重塑計算世界。在各種平台中，我們專注於在相同原子態中編碼的量子位元（qubits），這些量子位元具有更高的保真度和移動性，提供了增強的連接性。標準的離子阱（trapped ions）方案依賴於集體運動，而在離子阱，離子穿梭過程需要停停走走和冷卻步驟，不可避免地導致保真度的損失和時間的增加。雷德堡（Rydberg）原子方案也需要在偶極有效範圍內的短程相互作用。光學共振腔可以調節兩個原子的基本糾纏。我們的邏輯閘設計通過改變兩個原子之間相對耦合來實現共振的Tavis-Cummings模型，這取決於它們的軸向位置。此外，通過引入雷射和適當的失諧條件，我們實現了一個有效的共振Tavis-Cummings模型，其相對耦合比由雷射束控制。總體來說，我們通過使兩個遠距離的離子/原子穿過長程腔模來實現CZ閘。離子/原子的穿越性質將糾纏過程與傳輸結合為一個步驟，顯著節省了時間。此外，由於我們的共振模型，我們的邏輯閘時間與非共振模型相比基本上更快，但對高品質共振腔的需求更高。此外，腔體調解的特性使我們的方案適用於各種原子系統，包括雷德堡原子和困離子。然而，對於混合系統，需要額外的設計考慮。

Quantum computing outperforms classical computing with exponential speedup, potentially reshaping the field of computing. Among various platforms, we focus on qubits encoded in identical atomic states, which possess higher fidelity and mobility, providing enhanced connectivity. Standard gate schemes with trapped ions rely on the ion shuttling process. In ion trap, ions require stop-and-go and cooling steps, inevitably leading to a loss of fidelity and increased time consumption. Rydberg atom gate schemes also require short-range interactions, restricted within the dipole effective range. Optical cavity can mediate the fundamental entanglement of two atoms. Our gate design utilises an on-resonance Tavis-Cummings model by altering the relative coupling between two atoms based on their axial position. Furthermore, with laser incorporation and proper detuning conditions, we achieve an effective on-resonance Tavis-Cummings model, with the relative coupling ratio controlled by laser beams. Overall, we achieve a CZ gate by entangling two distant ions/atoms by passing them through a long-range cavity mode. The drive-through nature of ions/atoms combines the entangling process with transportation in a single step, significantly saving time. Also, as of on-resonance model, our gate time is fundamentally faster compared with off-resonance model but accompanied with stronger demand of high Q cavity. Additionally, the cavity-mediated nature makes our scheme applicable to various atomic species, including Rydberg atoms and trapped ions. However, additional design considerations are required for mixed platforms.