Quantum Computing with Cs Atoms in a 3D Optical Lattice

3D 光学晶格中铯原子的量子计算

• 批准号: 2112842
• 负责人: David Weiss
• 金额: $ 40万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2112842&HistoricalAwards=false
• 关键词: Quantum; Computing; Cs; Atoms; 3D; Quantum; Computing; Cs; Atoms; 3D

Quantum computers are built around quantum bits, or qubits. Unlike classical bits, which can be either 0 or 1, qubits can be in quantum superpositions of these two states. Furthermore, two qubits can be quantum entangled. An example of an entangled two qubit state is 00+11, where the system is in a superposition of both qubits in state 0 and both qubits in state 1. With N qubits, a system can simultaneously be in 2^N unique states at once. Such entanglement gives a quantum computer its power, allowing some properly framed problems that are intractable on classical supercomputers to be solved with as few as 60 qubits. For this project, the troup will be working on a new method to entangle neutral atom qubits, a platform that has seen the most dramatic advances in the last few years. These qubits are identical, they can be well isolated from their environment, and their internal states can be precisely controlled and measured, all critical qubit features. The experimental system is unique, in that it is possible to densely trap 3D arrays of atoms, which allows for superlative connectivity among qubits and a high density of quantum information. The entangling procedure could also be applied in more common 1D and 2D neutral atom arrays.The group will implement a variant of a two-qubit Rydberg gate for entangling neutral atoms. One ground qubit state will be excited to a high lying Rydberg state by a two-photon transition using an ultraviolet (UV) photon and a microwave photon. This approach has most of the advantages of using a Rydberg S state, which are reduced sensitivity to photoionization and electric fields, isotropic dipole-dipole coupling, and a simple fine structure. It avoids the use of high visible light powers that can cause photoionization, spontaneous emission, and large, unwanted ac Stark shifts. The large dipole matrix element for the microwave part of the transition allows for fast gates. Although the UV plus microwave Rydberg excitation technique could be used for any neutral atom array, it will be developed here for atoms trapped in a 3D optical lattice. Toward this end, the group will implement an “anti-addressing” technique that is able to select which atoms to entangle while minimally affecting the two-qubit gate fidelity or the surrounding quantum information. The goal is for each atom to be selectively entanglable with any of 24 surrounding atoms, a very high connectivity. The gate will be implemented on significantly colder and better localized atoms than previous Rydberg gates, which should help to reach the two-qubit gate fidelity goal of 0.999. Other experimental modifications, including implementing gray molasses for the initial loading and increasing the volume of atoms that can be accessed using one and two qubit addressing techniques, will raise the number of addressable qubits in the 3D array to 250.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.

量子计算机围绕量子位或Qubits构建。与经典位不同，可以是0或1，Qubits可以是这两种状态的量子叠加。此外，可以纠缠两个量子位。一个纠缠两个量子状态的一个示例是00+11，其中系统在状态0中的两个量子位和状态1中的两个量子位。使用n个量子位，系统可以同时仅在2^n个唯一状态下。这种纠缠赋予了量子计算机的功率，从而使一些适当的框架问题在经典的超级计算机上可以用只有60个Quarbits解决。对于这个项目，该团将采用一种新方法来纠缠中性原子量子位，该平台在过去几年中取得了最大的进步。这些量子位是相同的，它们可以与环境隔离，并且可以精确控制和测量其内部状态，所有关键的量子功能。实验系统是唯一的，因为它可以密度陷阱3D原子阵列，从而可以在数量和高密度的量子信息之间建立最高的连通性。纠缠过程也可以应用于更常见的1D和2D中性原子阵列中。该组将实现一个两Q Quibit Rydberg Gate的变体来纠缠中性原子。使用紫外线（UV）光子和微波炉光子的两光子过渡，一个地面Lydberg状态将被激发到高躺的Rydberg状态。这种方法具有使用rydberg的状态的大多数优点，这些状态降低了对光电电场和电场的敏感性，各向同性偶极 - 偶极偶联以及简单的精细结构。它避免使用高可见光功率，该功率可能导致光电离心，赞助发射以及大型不必要的AC鲜明变化。过渡的微波部分的大偶极基质元件允许快速门。尽管可以将UV Plus Microwave Rydberg兴奋技术用于任何中性原子阵列，但它将在这里开发用于被困在3D光学晶格中的原子。为此，该小组将实施一种“抗原”技术，该技术能够选择哪些原子纠缠，同时最小化两分之二的门忠诚度或周围的量子信息。目标是使每个原子与24个周围原子中的任何一个有选择性地纠缠在一起，这是非常高的连接性。与以前的Rydberg Gates相比，该大门将在明显更冷，局部原子更高的原子上实施，这应该有助于达到0.999的两个Qubit Gate Fidelity目标。其他实验性修饰，包括为初始负载实施灰糖，并增加可以使用一个和两个量子问题寻址技术访问的原子的数量，这将使3D阵列中的可寻址量子数的数量提高到250。此奖项反映了NSF的法定任务，并通过使用基金会的智力效果和宽阔的范围来评估，并以评估为贵重的智力。