The global race to make a practical quantum computer just took a big leap forward

In the global pursuit of developing advanced quantum computers, researchers have made a significant breakthrough with the introduction of Helios, a new trapped-ion quantum computer. Unlike other quantum computers, Helios operates using a unique architecture called a quantum charge-coupled device (QCCD), which physically transports charged objects (ions) electrically from storage to processing regions.

This innovative design sets it apart from other quantum computing architectures, such as superconducting qubits, where qubits are fixed in space and processing is executed by electrical signals switched on and off in time.

Helios features 98 qubits, making it the largest trapped-ion quantum computer built to date. The QCCD approach boasts several advantages that contribute to its superior performance. Gates operating on certain qubits do not affect their neighbors, reducing crosstalk and leading to better performance. Additionally, the QCCD architecture allows for the measurement and reset of qubits during computation, enabling the detection and correction of inevitable errors at the earliest possible time, further improving performance.

Lastly, the ability to access and return qubits from various parts of the memory after processing enables distant qubits to be connected, resulting in more efficient operation.

The Helios device has demonstrated all these advantages through the use of two major advances: hardware and software. The four-way X junction allows the system to handle several tasks simultaneously, significantly faster than earlier QCCD machines that could only move data back and forth in a single line or loop. Moreover, Helios relies on a new classical control software called Helios runtime, which optimizes the routing of data, further enhancing the efficiency of the computations.

Despite these advancements, Helios' computations have primarily consisted of random benchmark tests, limiting the practical significance of this leap forward. To perform quantum computations of practical importance, quantum computers would need to be significantly larger, with estimates suggesting the need for devices with a trillion operations and millions of qubits.

Building such fault-tolerant quantum computers (FTQCs) using the Helios device or any other known architecture remains a formidable challenge. It would require connecting thousands of QCCD devices, each containing thousands of qubits, via quantum links, and overcoming the physical transport of qubits, which is a slow process due to the use of precise voltages.