Trapped ions constitute one of the most promising systems for implementing quantum computing and networking^1,2. For large-scale ion-trap-based quantum computers and networks, it is critical to have two types of qubit: one for computation and storage, and another for auxiliary operations such as qubit detection³, sympathetic cooling^4,5,6,7 and entanglement generation through photon links^8,9. Although the two qubit types can be implemented using two different ion species^{3,10,11,12,13}, this approach introduces substantial complexity into creating and controlling each qubit type^14,15. Here we resolve these challenges by implementing two coherently convertible qubit types using one ion species. We encode the qubits into two pairs of clock states of the ¹⁷¹Yb⁺ ions, and achieve microsecond-level conversion rates between the two types with one-way fidelities of 99.5%. We further demonstrate that operations on one qubit type, including sympathetic laser cooling, single-qubit gates and qubit detection, have crosstalk errors less than 0.06% on the other type, which is below the best-known error threshold of ~1% for fault-tolerant quantum computing using the surface code^1,16. Our work establishes the feasibility and advantages of using coherently convertible dual-type qubits with the same ion species for large-scale quantum computing and networking.

^{俘获离子构成了实现量子计算和网络1,2}的最有前途的系统之一。对于基于离子阱的大规模量子计算机和网络，拥有两种类型的量子比特至关重要：一种用于计算和存储，另一种用于辅助操作，例如量子比特检测³、交感神经冷却^{4、5、6、7}和通过光子链接^8,9产生纠缠。尽管可以使用两种不同的离子种类^{3、10、11、12、13来实现这两种量子位类型，但这种方法在创建和控制每种量子位类型14、15}时引入了相当大的复杂性. 在这里，我们通过使用一种离子种类实现两种相干可转换的量子比特类型来解决这些挑战。^{我们将量子比特编码为171} Yb ⁺离子的两对时钟状态，并实现了两种类型之间的微秒级转换率，单向保真度为 99.5%。我们进一步证明，对一种量子比特类型的操作，包括交感神经激光冷却、单量子比特门和量子比特检测，在另一种类型上的串扰误差小于 0.06%，低于最著名的故障误差阈值约 1% - 使用表面代码^1,16的容错量子计算. 我们的工作确立了使用具有相同离子种类的相干可转换双型量子比特进行大规模量子计算和网络的可行性和优势。