Quantum Error Correction with A Dual Species Atomic Qubit Array

量子计算因其在解决经典计算机上难以解决的实际问题方面的潜力而引起人们的极大兴趣。应用领域包括密码学、新功能材料或化合物的设计，以及利用量子力学现象加速人工智能的机器学习系统。今天的经典计算机是非常可靠的，因为它们包含了在中断计算机运行之前纠正不常见但不可避免的电子错误的电路。为了充分发挥量子计算机的潜力，它们还需要纠错电路。在量子计算机上纠正错误比在经典计算机上纠正错误要困难得多，因为量子态有一个连续的值范围，而不仅仅是经典计算机的二进制0或1。这个项目将展示在量子计算机上实施纠错的新方法。该方法将使用两个不同的原子元素，一个元素保存要保护的数据，而另一个元素将用于检测发生的错误。当检测到错误时，将对数据应用操作以纠正错误。这些想法将在具有纠错功能的小型量子计算机原型中进行实验演示。此外，该项目还将通过培训学生来促进劳动力的科学发展。培训将是跨学科的，借鉴原子和激光物理、电子和计算机控制系统以及量子信息理论的方法和想法。研究成果将被纳入大学的教学课程。该项目将促进使用原子量子比特进行量子计算的最先进水平。它将在一次实验中使用两种不同的原子元素实现新的量子误差校正方法。一个用Cs原子编码数据量子比特，用Rb原子编码的两物种阵列将被用来演示量子错误的纠正和编码的逻辑量子比特对消相干的保护。其中一个物种(Cs)将被用来编码数据量子比特。其他物种(Rb)将被用作测量量子比特。量子信息将使用双物种量子门从Cs传输到Rb，然后作为纠错协议的一部分，将测量Rb原子。这种双物种阵列将使用一种新的技术，只需要单一波长的俘获光来限制空间交错阵列中的两种不同的原子元素。在同一类型的原子对和不同类型的原子对之间创建纠缠的量子逻辑门将通过用激光脉冲激励原子到里德堡态来实现。该项目的主要目标将是演示使用表面代码和7量子比特Steane代码准备逻辑量子比特。将研究逻辑编码状态的相干特性，并将在逻辑量子之间演示门。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum computing is attracting great interest due to its potential for solving practical problems that are intractable on classical computers. Areas of application include cryptography, design of new functional materials or chemical compounds, and speed up of machine learning systems for artificial intelligence using quantum mechanical phenomena. Today’s classical computers are extremely reliable because they incorporate circuitry for correcting infrequent, but unavoidable electronic errors before they disrupt the operation of the computer. For quantum computers to achieve their full potential they will also need error correcting circuitry. Correcting errors on a quantum computer is much more difficult than correcting errors on a classical computer because quantum states have a continuous range of values, not just the binary 0 or 1 of a classical computer. This project will demonstrate new approaches to implementing error correction on a quantum computer. The approach will use two different atomic elements, with one element holding the data to be protected while the other element will be used to detect errors that occur. When an error is detected operations will be applied to the data to correct the errors. These ideas will be demonstrated experimentally in a prototype, small scale quantum computer with error correction. Aditionally the project will contribute to scientific workforce development through training of students. The training will be interdisciplinary, drawing on methods and ideas from atomic and laser physics, electronic and computer based control systems, and quantum information theory. Research results will be incorporated into the University teaching curriculum.The project will advance the state of the art in quantum computation using atomic qubits. It will implement novel approaches to quantum error correction using two different atomic elements in a single experiment. A two-species array with data qubits encoded in Cs atoms and ancillas in Rb atoms will be used to demonstrate correction of quantum errors and the protection of encoded logical qubits against decoherence. One of the species (Cs) will be used to encode data qubits. The other species (Rb) will be used as measurement qubits. Quantum information will be transferred from Cs to Rb using a two-species quantum gate, and the Rb atoms will then be measured as part of the error correction protocol. The two-species array will use a novel technique that requires only a single wavelength of trapping light to confine two different atomic elements in spatially interleaved arrays. Quantum logic gates to create entanglement between pairs of atoms of the same type as well as pairs of atoms of different types will be performed by exciting atoms to Rydberg states with laser pulses. The major goals of the project will be to demonstrate preparation of logical qubits using the surface code and the 7-qubit Steane code. The coherence properties of logically encoded states will be studied and gates will be demonstrated between logical qubits.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.